Tesi sul tema "Flavor perception"

For water suppliers, using chlorine is necessary to ensure water bacteriological quality from the treatment plant to the consumers' tap. However, chlorine flavour is one of the most common reasons advocated for choosing tap water alternatives as drinking water. As a consequence, the putative link between chlorine flavour perception and tap water consumption is an issue in drinking water habits studies. Since the sensory mechanisms involved in chlorine flavour perception remained largely unknown, the main objective of this thesis work was to first highlight those mechanisms and then to identify potential lever chlorine flavour sensory neutralisation.In a first step, we demonstrated that hypochlorous acid associated, which is likelyresponsible of chlorine flavour in tap water, could activate the olfactory system at low concentrations and the trigeminal system for concentrations up to 4 mg/L Cl2. Additionally, our results suggested that tap water consumption does not seem to be related to sensitivity to chlorine flavour but rather to consumers' tap water representation.In a second stage, we explored the impact of water mineral matrix on chlorine flavour perception. We demonstrated first that water molarity and cationic content variations modulate drinking water taste. We also evidenced that chlorine flavour intensity is modulated according to water composition. Nevertheless, our data suggest that physico-chemical, in- mouth physiological and sensory mechanisms are likely involved in such modulation.In the last part of the Thesis work, we investigate the putative influence of aroma perceptionon chlorine flavour. Our results showed that beyond chemical reactions between hypochlorous acid and odorants, aromas at peri-threshold concentration enhance chlorine flavour and decrease tap water acceptability

Les glycosidases, en particulier les β-glucosidases, catalysent l'hydrolyse des liaisons glycosidiques, libérant des molécules de sucre et des aglycones. Dans la cavité buccale humaine, il a été précédemment proposé que les β-glucosidases du microbiote buccal libèrent des composés aromatiques.Cette thèse vise à identifier les glycosidases bactériennes buccales impliquées dans la libération d'arômes. Sept glycosidases du microbiote buccale ont été identifiées, exprimées et purifiées, incluant celles de Veillonella sp. (VsBGlu1 et VsBGal1), Prevotella sp. (PsBG1), Streptococcus pneumoniae (SpBG1), Actinomyces naeslundii (AnBG1), Streptococcus salivarius (SsBG1), et Granulicatella adiacens (GaBG1). L'analyse cinétique a montré que PsBG1 possède une grande efficacité catalytique envers les β-glucopyranosides et peut hydrolyser divers glucosides aromatiques et aliphatiques, libérant des composés volatils tels que le salicylaldéhyde, l'octanol et l'hexanol. L'analyse de la structure cristallographique de PsBG1 par diffraction des rayons X a révélé une structure caractéristique de la famille 1 des hydrolases glycosidiques. Grâce à la co-cristallisation avec une molécule de glycérol, un ensemble d'acides aminés a été proposé pour leurs rôles dans la reconnaissance du substrat et la catalyse. Dans une matrice alimentaire complexe, PsBG1 a efficacement hydrolysé des substrats glycosidiques en métabolites volatils. Les β-glucosidases de Actinomyces naeslundii et Granulicatella adiacens ont également montré une activité envers des substrats glycosidiques aromatiques présents dans les produits alimentaires.Cette étude fournit une caractérisation détaillée des β-glucosidases du microbiote buccal humaine, démontrant leur rôle dans l'hydrolyse des précurseurs d'arômes et leur rôle potentiel dans la perception des saveurs
Glycosidases, particularly β-glucosidases, catalyze the hydrolysis of glycosidic bonds, releasing sugar molecules and aglycones. In the human oral cavity, β-glucosidases from the oral microbiota have previously been proposed to release aromatic compounds.This thesis aims to identify bacterial oral glycosidases involved in aroma release. Seven glycosidases from the oral microbiota were identified, expressed, and purified, including those from Veillonella sp. (VsBGlu1 and VsBGal1), Prevotella sp. (PsBG1), Streptococcus pneumoniae (SpBG1), Actinomyces naeslundii (AnBG1), Streptococcus salivarius (SsBG1), and Granulicatella adiacens (GaBG1). Kinetic analysis showed that PsBG1 has high catalytic efficiency towards β-glucopyranosides and can hydrolyze various aromatic and aliphatic glucosides, releasing volatile compounds such as salicylaldehyde, octanol, and hexanol. X-ray crystallography analysis of PsBG1 revealed its characteristic glycoside hydrolase family 1 structure. Through co-crystallization with a glycerol molecule, a set of amino acids was proposed for their roles in substrate recognition and catalysis. In a complex food matrix, PsBG1 effectively hydrolyzed glycosidic substrates into volatile metabolites. The β-glucosidases from Actinomyces naeslundii and Granulicatella adiacens also showed activity towards aromatic glycoside substrates found in food products.This study provides a detailed characterization of human oral microbiota β-glucosidases, demonstrating their role in the hydrolysis of aroma precursors and their potential role in flavor perception

Mestrado em Viticultura e Enologia - Instituto Superior de Agronomia - UL / Faculdade de Ciências - Universidade do Porto
The present work was aimed at the evaluation of the sensory and liking responses induced by dry white wine modified with increasing flavor concentrations. The tasting panel was composed by 34 trained subjects which were characterized according to gender, smoking habits, vinotype, 6-n-propylthiouracil (PROP) status, saliva flow, sodium chloride sensitivity, tartaric acid, tannic acid sensitivity and sweet liking. Tasters scored the intensity elicited by white wine spiked with different tastants (tartaric acid, sucrose or tannic acid) or increasing levels of a fruity flavor mixture together with their liking evaluation. The wines with different flavor concentrations were perceived increasingly sweet with constant sourness and saltiness. The tasting panel showed two groups responding differently to orthonasal flavor intensity measured as the longest distance, in cm, from the glass top where the smell is sensed. High and low smell sensitivity individuals showed equal (p<0.05) response to wine sweetness and wine liking while the former group provided lower sourness and saltiness scores. In addition, tasters highly sensitive to all tastes or to sucrose in wine scored aroma intensity with higher values (p<0.05). Given that the increasingly flavored white wines were perceived different only in their sweetness, the liking scores could only be attributed to congruent perception of fruity flavors and sweet mouthfeel. The preference for white wine was constant across all flavor concentrations, being dependent on some taster categories. Males, non-smokers, PROP medium tasters and low saliva producers yielded higher (p<0.05) liking scores than the respective counterparts. The sensitivities to sourness, sweetness or astringency did not influence preference scores. The Vinotype Sensitive individuals provided higher (p<0.05) liking scores than hypersensitives or tolerants. In conclusion, the results suggested that taste sensitivity had only a minor role on shaping the individual preferences of white wine
N/A

Thesis: S.M., Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 119-126).
This thesis presents a study of how hearing and taste can influence each other, how this interaction can be measured, and how the results can be used to design new, powerful, immersive experiences. The goal of the thesis is to address two questions: does music significantly change flavor perception, and can music change the hedonic experience of a meal? Experimentally, I looked at ways to measure changes in sensory perception. Artistically, I explored how external factors can alter the eating experience. From a cultural perspective, I examined the history of multisensory experiences - in feasts, in everyday cooking, and in community rituals. I conducted a series of experiments to measure the effect of music on flavor perception, and designed a series of novel eating experiences that make use of congruencies between multiple senses, culminating in a multisensory feast for the Media Lab. From these studies, design patterns and challenges are extracted and analyzed, and new directions are discussed.
by Qian (Janice) Wang.
S.M.

Metallic flavors are of concern for many industries including food, health, and water. Metallic off-flavor, induced by ferrous sulfate solution (10mg/L), and its remediation using pre- and post-rinse treatments of water (control) or metal chelators, were studied. Metal chelators included lactoferrin (1 ?M), a natural metal-binding protein in milk and saliva, and EDTA (36 ?M), a synthetic chelator. Time-intensity (TI) evaluation (n=6, 4 female; age 40-70) of lingering metallic flavor indicated that metallic flavor decreased with a post-rinse adjuvant treatment of lactoferrin as indicated by a reduced maximum intensity and area under the curve compared to a pre-rinse treatment; EDTA and water post-rinses were equally effective for three of the TI parameters. Alterations in salivary components were studied in saliva collected (n=8; 5 female, age 40-70) after sipping a lactoferrin solution (1?M) followed with a ferrous sulfate sample (10 mg/ml) to stimulate metallic flavor, as compared to unstimulated whole saliva. Protein concentration, oral lipid oxidation as indicated by thiobarbituric acid reactive substances assay, and iron concentration were determined on individual saliva samples, with no significant differences found between treatments (p>0.05). Protein patterns were qualitatively characterized for each pre-rinse and metallic stimuli from four panelists by two-dimensional gel electrophoresis. A consistent pattern of regions containing major salivary components was observed. This research has shown that lactoferrin protein is a potential natural alternative to synthetic EDTA for reducing iron-induced metallic off-flavors. This study provides a foundation of method development to better understand salivary protein interaction with metals and flavor perception.
Master of Science in Life Sciences

During 20th century main concern was to have sanitary water flowing through the tap. In 21st century constant supply of safe drinking water is common at any home in USA. Hence consumers pay attention to aesthetic quality of tap water. Odorous algal metabolites in source water and metals introduced to drinking water due to corrosion of pipes in the distribution system cause taste, odor and color problems, and result in complaints and perception of tap water as unhealthy. Millions of dollars are spent each year by water industry to address and prevent these issues. This research focused on some of the taste-and-odor issues associated with drinking water. First aim was to understand when geosmin, 2-MIB, and nonadienal become detectable, employing two-resistance mass transfer theory to determine the concentration of odorants in bathroom air. Results showed that water temperature and odorant concentration in water play an important role. Next focus was to develop an international odor standard to be used for training of sensory analysis panelists. There are many sensory methods to monitor drinking water to detect the off-flavors however an odor standard has been missing. Hexanal was studied with trained flavor profile analysis panels and was proposed as an ideal odor reference standard to be used for training and sensory assessment of water samples. Main focus was to understand metallic flavor of drinking water caused by iron and copper. It was shown that metallic sensation has taste and retronasal components creating the flavor and humans are very sensitive to it. Occurrence of lipid oxidation in the oral cavity was shown when metals were ingested, that produces carbonyls which are responsible for the metallic flavor. Antioxidants and chelators were investigated to study prevention of lipid oxidation and, chelators were determined to be more effective. Oral epithelial cell cultures were developed as a model for oral cavity to further investigate lipid oxidation and effectiveness of the antioxidants and chelators. This dissertation is a result of inter-disciplinary work and possibly a good example for how problems may be solved by incorporating different methods and point of views from several disciplines.
Ph. D.

Thesis (Ph. D.)--University of Florida, 2002.
Title from title page of source document. Document formatted into pages; contains xii, 130 p.; also contains graphics. Includes vita. Includes bibliographical references.

Le concept de fraîcheur a été récemment étudié en sciences du consommateur en raison de sa dimension hédonique influençant les préférences des consommateurs. Les études antérieures ont conclu que la fraîcheur pouvait résulter d’une intégration multisensorielle des signaux olfactifs, gustatifs, trigéminaux, visuels et auditifs. Dans les boissons, la fraîcheur est également complexe au niveau sémantique puisqu'elle peut avoir des significations différentes. La plupart des études se sont concentrées sur les attentes des consommateurs à partir de données déclaratives. Compte tenu de la complexité des mécanismes cognitifs impliqués, des mesures plus objectives du comportement sont apparues nécessaires. Dans cette thèse, nous avons ciblé l’influence des interactions audiovisuelles à partir desquelles les consommateurs perçoivent une boisson comme fraîche, avant la dégustation. Nos résultats révèlent que des stimuli audiovisuels liés à la température et la carbonatation influencent positivement la fraîcheur perçue. L'existence d’effets de correspondance audiovisuelle entre la taille des bulles et la hauteur des sons dans les boissons pétillantes ont également été montrés et se sont avérés être robustes à des variations du stimulus ainsi qu’au paradigme expérimental utilisé. Enfin, les effets de correspondance observés entre taille des bulles et hauteur du son seraient plus susceptibles de se produire lorsque l’attention des participants est dirigée sur les caractéristiques pour lesquelles la correspondance est testée. Certains mécanismes cognitifs sous-tendant la perception multisensorielle de fraîcheur pourraient aider à augmenter l'attractivité et l'appréciation des boissons
The concept of freshness has received recent consideration in the field of consumer science, mainly due to its hedonic dimension, assumed to influence consumers’ preference and behavior. Previous studies concluded that freshness could be defined as the result of the multisensory integration of olfactory, gustatory, trigeminal, visual, and auditory cues. In the case of beverages, freshness is also complex at a semantic level since it conveys different meanings. Up to now, most studies focused on consumers’ expectations by a collection of declarative data. Given the complexity of the perceptual and cognitive mechanisms involved, this approach needed to be completed by more objective measures of behavior. In this thesis, we focus on the influence of audiovisual interactions from which consumers can perceive a beverage as fresh, before tasting. The first experiments revealed that audiovisual stimuli cuing temperature and carbonation positively influence the perception and categorization of freshness in beverages. The second experiments revealed the existence of audiovisual crossmodal correspondence effects between bubbles size and pouring sounds pitch in carbonated beverages that were robust to variations of the stimulus context as well as the experimental design used. A final experiment revealed that the Pitch-Size correspondence effects in beverages are more likely to occur when the participants’ attention is directed toward the same features on which the correspondence is tested. Applications such as the triggering of perceptual and cognitive mechanisms underpinning the multisensory perception of freshness could help to increase beverages’ attractiveness and appreciation

Au cours des dernières années, les autorités sanitaires ont recommandé une réduction de la teneur en sel et en gras dans la consommation alimentaire quotidienne. Cependant, les aliments à teneur réduite en sel et en gras sont souvent peu appréciés par les consommateurs, ce qui a amené au développement des recherches sur les stratégies possibles pour maintenir l’acceptabilité des aliments tout en réduisant les teneurs en ces ingrédients. Dans cette thèse, l’intégration multi-sensorielle et les cinétiques de libération du sel et des arômes mesurées in vitro ont été étudiés pour évaluer leur potentialité à compenser une réduction en sel et matière grasse d’un fromage modèle de composition variable et d’un fromage réel (type trappiste).Dans une première étape, une approche sensorielle a permis d’étudier les interactions multi-sensorielles arômes-saveurs-texture pour les formages modèles et réels. La structure et la perception sensorielle de vingt-quatre modèles fromagers variant en composition (2 niveaux de gras, 2 de sel, 2 de pH à l’emprésurage) et aromatisés avec un arôme de sardine (associé au sel), d'un arôme de beurre (associé au gras) ou non aromatisés (témoin) ont été caractérisés par des mesures rhéologiques (compression uniaxiale) et des mesures sensorielles (profil descriptif). Les résultats ont montré une influence de la composition sur la structure et la texture perçue des produits. Par ailleurs, l’arôme sardine a conduit à une perception plus salé ; l’arôme de beurre a permis de renforcer la perception du caractère gras. Toutefois cette influence des arômes sur les autres dimensions sensorielles est fonction de la texture des produits donc de leur composition et de leur structure. Ces résultats ont été étendus à des fromages réels avec toutefois des spécificités. Si l’arôme sardine renforce la perception du sel, seul l’arôme de beurre associé à l’arôme de sardine permet de renforcer le caractère gras.Dans une deuxième étape, une approche physico-chimique a été développée pour explorer les cinétiques de libération des stimuli odorants et sapides dans des conditions simulant la mastication in vitro à l’aide d’un simulateur de mastication. L’objectif était d’utiliser les données ainsi obtenues pour expliquer l’influence de la structure des produits et de leur déstructuration lors de la mastication sur les effets sensoriels observés dans la première étape. Les modèles fromagers et les fromages réels ont été ainsi étudiés. La libération des composés volatils a été évaluée en connectant le simulateur de mastication à un spectromètre de masse à pression atmosphérique (PTR-MS) ; la libération du sodium a été suivie grâce à une sonde de conductivité. Les résultats ont montré une influence des trois paramètres de composition (teneur en matière grasse, en sel et pH à l’emprésurage) sur les cinétiques de la libération des arômes. Cette variation dépend néanmoins de la nature de l’arôme suivi ; les arômes plus hydrophobes étant moins sensibles aux variations de la teneur en matière grasse et plus sensibles aux variations de pH et donc à la structure du produit. La cinétique de libération du sel lors de la mastication in vitro est aussi largement influencée par la composition et la structure des produits. Outre la teneur en sel qui conditionne les quantités libérées, la teneur en matière grasse et le pH à l’emprésurage module la cinétique de libération du sel. Au final, ces travaux montrent une importante contribution de la cinétique de libération et donc probablement de la temporalité des sensations dans perception globale du sel et de la matière grasse lors de la consommation d’un aliment complexe
In recent years, health authorities worldwide advise for a reduction of salt and fat in daily food consumption. However, foods with reduced salt and fat content are often not appreciated by consumers, Therefore, the formulation of low-salt-fat foods that maintain acceptability is a major concern in food research. In this thesis, the multi-sensory integration and release kinetics of flavor compounds were explored as strategies to compensate for salt and fat reduction in cheese products (model cheeses and real cheeses). The objective was to better understand the mechanisms leading to aroma and salt release during mastication and to evaluate how the matrix composition and structure influence salt and aroma release profile.Multisensory integration approach to compensate for salt and fat reduction was studied in a first step. The structure and sensory perception of 24 cheese models varying in composition (2 levels of fat, 2 salt, 2 pH at renneting) and flavored with either a sardine aroma (associated to salt), a butter aroma (associated to fat) or not flavoured (control) were characterised by rheological measurements (uniaxial compression) and sensory evaluation (descriptive analysis). The results demonstrated an influence of the composition on the products structure and perceived texture. Furthermore, a significant saltiness enhancement was induced by sardine aroma while significant fat perception enhancement was induced by butter aroma. However, this influence of the aroma on other sensory dimensions depends on the texture of the products thus on their composition and structure. These results have been extended to real cheeses but with specificities. If the sardine flavor enhanced the perception of salt, only butter-sardine-flavor enhanced the perception of fat.In a second step, a physico-chemical approach was developed to explore the release kinetic of flavor compounds during in vitro breakdown using a chewing simulator. The aim was to use these data to explain the influence of the structure of model cheeses and real cheeses and their breakdown during chewing on sensory effects observed in the first step. Volatile compounds release was monitored by connecting the chewing simulator to a proton transfer reaction-mass spectrometry (PTR-MS), while salt release was monitored using a conductivity probe. Results showed that product composition and structure (fat, salt and pH at renneting) influenced aroma release, which however depends on the nature of the aroma: the more hydrophobic compounds are less sensitive to variations in fat content and more sensitive to variations in pH and therefore to the products structure. The salt release kinetic during in vitro chewing was also influenced by the composition and structure of the products. Indeed, beyond salt content which determined the amount of salt released, fat content and the pH at renneting modulated the release kinetic. In conclusion, this work showed a significant impact of the flavor compounds release kinetic and probably of temporality of sensations on the overall perception of salt and fat when consuming a complex food

Flavour perception of food and beverages is a complex multisensory experience involving the gustatory, olfactory, trigeminal, auditory and visual senses. Thus, investigations into multimodal flavour perception require a multidisciplinary design of experiments approach. This research has focussed on beer flavour perception and the fundamental interactions between the main flavour components - sweetness, bitterness (from hop acids), alcohol content and carbonation level. A model beer was developed using representative ingredients which could be manipulated to systematically vary the concentration of the main flavour components in beer and was used in the following experiments. Using a full factorial design, the physical effect of ethanol, C02 and hop acid addition was determined by headspace analysis and in-nose expired breath (in-vivo) measurements. Results from headspace and in-vivo methods differed and highlighted the importance of in-vivo measures when correlating to sensory experience. Ethanol and C02 significantly increased volatile partitioning during model beverage consumption. The effects of ethanol and C02 appeared to be independent and therefore additive, which could account for up to 86% increase in volatile partitioning. This would increase volatile delivery to the olfactory bulb and thus potentially enhance aroma and flavour perception. This was investigated using quantitative descriptive analysis. Results showed that C02 significantly impacted all discriminating attributes, either directly or as a result of complex interactions with other design factors. C02 suppressed the sweetness of dextrose and interacted with hop acids to modify bitterness and tingly perception. Ethanol was the main driver of complexity of flavour and enhanced sweet perception. In a first study of its kind, the impact of C02 on gustatory perception was further investigated using functional magnetic resonance imaging (fMRI) to understand cortical response. In addition, classification of subjects into PROP taster status groups and thermal taster status groups was carried out. Groups were tested for their sensitivity to oral stimuli using sensory techniques and for the first time, cortical response to taste and C02 was investigated between groups using fMRI techniques and behavioural data. There was no correlation between PROP taster status and thermal taster status. PROP taster status groups varied in their cortical response to stimuli with PROP super-tasters showing significantly higher cortical activation to samples than PROP non-tasters. The mechanism for thermal taster status is not currently known but thermal tasters were found to have higher cortical activation in response to the samples. The difference in cortical activation between thermal taster groups was supported by behavioural data as thermal tasters least preferred, but were more able to discriminate the high C02 sample than thermal non-tasters. This research has provided in-depth study into the importance of flavour components in beer. It advances the limited data available on the effects of C02 on sensory perception in a carbonated beverage, providing sound data for the successful development of products with reduced ethanol or C02 levels. The use of functional magnetic resonance imaging has revealed for the first time that oral C02 significantly increases activation in the somatosensory cortex. However, C02 seemed to have a limited impact on activation strength in 'taste' areas, such as the anterior insula. Research comparing data from PROP taster status groups and thermal taster status groups has given insight into the possible mechanisms accounting for differences in oral intensity of stimuli.

A psychophysical approach was applied to study cross-modality between texture, sweetness and aroma in a real food system (biscuits). A range of biscuits varying in fat, flour and sugar levels as well as sugar form and sugar pre-treatment were made according to a statistical D-optimal Mixture Design (main effects crossed with a categorical factor). This allowed control of the interactions between ingredients in the complex biscuit system but also expressed ingredient-texture relationships in mathematical terms. Studying biscuit texture (structure and mechanical properties) revealed that the biscuit system was dominated either by a glassy sucrose (dissolved sugar) or crystalline sucrose (granulated sugar) rich matrix embedding more or less native starch granules, irrespective of which sugar form was used, fat formed a continuous layer and acted as a "glue" to hold the biscuit matrix together. With the exception of gluten development, flour did not play a significant role in the formation of the biscuit structure.

A newly recruited sensory panel was trained in magnitude estimation and time intensity sensory techniques. Sensory analysis was combined with instrumental analysis using MS Nose to investigate the relationship between stimulus and perception using simple model food systems. Volatile release data was collected after swallowing aqueous solutions containing a cocktail of aroma compounds. The compounds varied in their persistence during subsequent exhalations dependent on the degree of association with the mucous lining of the throat. The rate of breathing had no effect on the shape or intensity of the release profile. The data was successfully modelled using the basic principles of interfacial mass transfer. The mechanistic model included some estimated parameters for un-measurable anatomical and physiological variables, kinetic properties of the flavour compound and terms to represent the oscillatory breathing and airflow rate. Aside from the 1st exhalation, the model fitted the data very well. The panel rated the intensity of minty flavor in a 6% gelatine gel, containing varying concentrations of carvone. The flavor was assessed using Magnitude Estimation and Time Intensity Methods. In addition, the quantity of carvone released from the gel and reaching the assessors nose was measured, breath by breath during eating, using the MS Nose. The results showed that the quantity of volatile delivered to the nose was directly proportional to the concentration in the sample, however, the absolute quantity varied greatly between individuals. Further differences were observed in the temporal dimension of their release profiles, which related to differences in their anatomy, physiology and eating habits. In some cases, these differences were mirrored by the sensory data. The relationship between perceived intensity and sample concentration was linear for both types of sensory data. Neither the speed of eating nor the concentration of volatile reached in-nose, affected an individuals ability to judge intensity. There was evidence to suggest, however, that the speed of eating affected the level of adaptation to the carvone stimulus. The affinity of the aroma compound for water (hydrophobicity) was an important factor in influencing the temporal characteristics of the instrumental and sensory data. When aroma release was rapid (< Tmax) the sensory response occurred slightly later whereas when the aroma release was much slower (>Tmax), with intensity increasing more gradually, the sensory response preceded the instrumental data. These phenomena were explained in terms of a lag phase for neural processing when the stimulus was presented quickly and adaptation to the stimulus when it was delivered over a longer period of time. A trained sensory panel assessed flavour and sweetness intensity in solutions containing varying concentrations of Hydroxy Propyl Methylcellulose (HPMC), sugar and flavour volatile. The flavour and sweetness of the viscous solutions were rated using magnitude estimation with a controlled modulus. In addition, the concentration of volatile released on the breath was measured using MS Nose. For low concentrations of HPMC (<0.5g/100g), perceived flavour intensity remained the same, however, a steady decrease was noted at higher concentrations (>0.6g/100g). The change in perceived intensity occurred at the point of random coil overlap (c*) for this hydrocolloid. The perceived sweetness of the solution showed a similar pattern with increasing HPMC concentration, although the inflection at c* was not so obvious. Despite the change in perceived flavour intensity, the actual concentration of volatile measured on the breath was not affected by the change in HPMC concentration. Low order polynomial models were produced to describe perceived flavour intensity and sweetness in viscous solutions containing HPMC and potential explanations for the changes in perception were discussed.

La perception de la flaveur des aliments dépend de la perception de plusieurs composés en mélange dans des proportions équilibrées. Interactions perceptives entre différents odorants ainsi que la libération dynamique des odorants par la matrice alimentaire sont les principaux facteurs qui influencent la perception globale. L’objectif de cette thèse de doctorat était d’étudier la perception du mélange d’odorants qui constituent l’arôme du fromage à pâte pressée, en prenant en compte les interactions perceptives et la dynamique de libération des composés par la matrice. Une stratégie, comprenant une caractérisation complète des odorants des fromages, suivie d’une recombinaison qualitative et d’une étude détaillée des rôles respectifs des composés clés, et finalement la prise en compte de la dynamique de libération par incorporation des composés dans une matrice fromagère, a été appliquée. Des caractérisations approfondies sensorielles et instrumentales nous ont permis de mettre en évidence des relations entre la perception sensorielle et la composition des composés volatils et proposer des hypothèses. La recombinaison des différents composés a été testée afin d’étudier le rôle de chacun en mélange. Aidés par des apprentis aromaticiens durant la phase des recombinaisons nous avons pu observer particulièrement que 12 composés étaient très importants pour l’odeur du fromage. Par la suite nous avons étudié des interactions entre odeurs en appliquant des techniques de stimulation odorante en phase gazeuse, puis la dynamique de libération des composés en incorporant l’arôme dans une matrice fromagère par des techniques permettant de mesurer la quantité libérée en fonction du temps
Perception of the aroma of food products depends both the chemical composition of food and human neurophysiology. The perception of food flavour, including cheese often relies on the perception of several aroma compounds in mixture in balanced proportions. Perceptual interactions among aroma compounds in mixtures and also the release of aroma compounds from the food product are the main factors that influence the global perceived aroma of food. Hence, the objective of this PhD study was to investigate the mixture of aroma compounds representing the aroma of semi-hard cheese by taking into account perceptual interactions among odorants and the dynamic release of the compounds by the cheese matrix. A strategy involving a complete characterisation of the cheeses followed by a recombination and investigation of the role of the key-aroma compounds and the dynamic release of the aroma compounds from the cheese matrix was taken into account. Comparison of the sensory and instrumental characteristics was made in order to highlight relationships between sensory perception of the aroma and the volatile composition of the cheeses and thus point out the molecular origins of the perceived cheese aroma. Recombination of selected aroma compounds was tested, in order to study the role of each aroma compound within the mixture. Especially 12 compounds seemed important for the semi-hard cheese aroma. To investigate the odour-odour interactions, different odour-stimulation tools were applied and dynamic release of aroma compounds was taken into account by incorporating the aroma compounds into a cheese matrix by different techniques allowing measuring the quantities released as function of time

Cette thèse a pour objectif d'étudier l'influence de la matrice alimentaire sur la libération et la perception des arômes. La première partie analyse le rôle de la pectine sur la diffusivité des arômes et sur les interactions moléculaires dans des systèmes modèles. La deuxième partie étudie le rôle des solides en suspension sur la répartition et la libération des arômes et sur la perception sensorielle dans le jus d'orange. La distribution des volatiles dans les différentes fractions du jus (pulpe, trouble et sérum) et le rôle des constituants non-volatils a premièrement été étudiée. En suite une méthodologie pour évaluer la qualité sensorielle des extraits en phase vapeur a été développée (Chromatographie gazeuse directe couplée à l'olfactométrie). Finalement, le rôle de la pulpe sur le profil sensoriel (texture, saveur, arôme odeur) du jus d'orange a été étudié. En parallèle, des analyses physico-chimiques, rhéologiques et la libération des arômes en phase vapeur ont été effectuées
The aim of this thesis was to investigate how the properties of the food matrix influence flavour release and perception in food. The thesis is organised in two parts. The first part focused on the role of pectins on aroma compound diffusivity and molecular interactions in a model system. The second part focused on the role of suspended solids on aroma compound distribution, flavour release and sensory perception in orange juice. Firstly we determined how aroma compounds are distributed within the macroscopic juice fractions (cloud, pulp and serum) and the role of non-volatile constituents. Secondly we developed a novel methodology (Direct Gas Chromatography Olfactometry) to evaluate the sensory quality of solventless extracts (e. G. SPME, static headspace). Finally, we investigated how pulp influence sensory profiles of texture, taste, odour and aroma in orange juice. At the same time rheological and physicochemical measurements as well as flavour release studies were performed

Les interactions perceptuelles entre différentes modalités sensorielles affectent la perception des aliments. Si ce phénomène a été largement étudié entre des stimuli olfactifs et gustatifs en solution aqueuse, peu d'études ont été menées avec des produits existants dans le commerce. Similairement, peu de travaux sont dédiés à l'étude des interactions multi-sensorielles impliquant l'olfaction, le goût et la perception tactile en bouche et à l'étude des perceptions dites complexes, c'est-à-dire qui impliquent plusieurs modalités sensorielles. Le premier objectif de ma thèse était l'exploration des mécanismes sous-jacents aux interactions perceptuelles existant entre l'olfaction et la gustation durant la consommation de produits réels, et en solution avec des stimuli olfactifs à une concentration infraliminaire. Cette approche a ensuite été étendue aux perceptions olfactive, gustative et tactile (en bouche) et à la perception complexe "rafraîchissante". Il a été mis en évidence que la familiarité d'un produit et la stratégie d'attention durant l'exposition affectent de façon critique les interactions perceptuelles. Pour la première fois il a été démontré qu'une concentration infraliminaire d'odorant associé au goût sucré (fraise) augmente la perception sucrée d'une solution de sucrose. La multiplicité des interactions sensorielles présente dans un milieu alimentaire complexe a également été mis en évidence à un niveau bimodal (ex: entre la perception amer et le froid) et tri-modal (ex: entre la perception olfactive, sucrée et froide). Finalement il été démontré que la perception rafraîchissante est construite sur la base d'une combinaison de déterminants sensoriels, d'habitudes alimentaires ainsi que de facteurs hédoniques et psychophysiologiques tels que l'énergie mental. Pour conclure, les connaissances acquises par ce travail soulèvent d'autres interrogations notamment à propos des mécanismes neuronaux sous-tendant la mémorisation des associations perceptuelles et des conditions requises en termes de durée et de fréquence d'exposition pour la mise en place de ces interactions

Freshness is a holistic attribute of a food product, with a meaning that most often includes how recently produced or harvested a food currently is and to what extent it has been preserved. Without knowledge of production date, consumers will judge perceived freshness by the sensory properties of foods. However, these properties are not easily identified and described, as they vary considerably between different product types. The objective of this thesis, was to determine the sensory properties that consumers most associate with baked product freshness, and to determine the volatile composition responsible for "fresh-baked" flavour. In addition, relationships were determined and modelled between volatile composition, sensory properties and perceived freshness, in order to predict perceived freshness without the need for further consumer testing. Two consumer studies were carried, where perceived freshness of 10 breads, 5 cakes and 5 biscuits was measured based on appearance, flavour and texture, and by product odour only. Individual differences in perceived freshness were represented on two-dimensional Freshness Maps generated using Principal Component Analysis (PCA). Consumers used similar terms to describe product freshness, but different terms were associated with specific product types. An understanding of the sensory characteristics associated with perceived freshness was determined by examining relationships between perceived freshness and descriptive analysis (DA). Sensory characteristics perceived to convey freshness in one product type did not necessarily convey freshness in another. Further relationships between perceived freshness and sensory characteristics were determined for 20 bread types. Descriptive analysis was carried out with all breads, whereas perceived freshness was measured for 10 of these. Three consumer clusters were identified that were homogenous in their freshness perceptions, indicating that perceived bread freshness varied among consumers. Perceived freshness of breads not evaluated by consumers, but assessed by descriptive sensory analysis, were predicted for each consumer cluster using Partial Least Squares Regression (PLSR). Most fresh breads were described as having "porous" appearance, "floury", "toasted" and "malty" odour, "sweet", "buttery", and "oily" flavour, and "sweet" aftertaste. Least fresh breads were described as "musty" odour, "sour" flavour and "sour" aftertaste. In addition, Proton Transfer Reaction Mass Spectrometry (PTR-MS) measured the volatile composition of all 20 bread types. Thirty-three mass ions significantly discriminated between bread types. Relationships were determined between odour and flavour sensory attributes, and mass spectral data using 15 of the 20 breads. PLSR models predicted the sensory properties and perceived freshness of all breads including five types not included in the construction of models. Bread perceived to be most fresh shared a similar combination of positively correlated mass ions, m/z 87, 97 and 117, also represented by "dairy" odour and "buttery" flavour, whilst the masses m/z 63, 69 and 91 were negatively associated with bread freshness, represented by the sensory attributes "grain", and "musty" odour, and "sour" flavour. The influence of sweetener, fat type and time from baking on perceived freshness was determined for cakes. Four sweeteners (sucrose, glucose, xylitol, isomaltose), three fat types (butter, margarine, shortening) and two times from baking (days zero and 15) were investigated. Descriptive analysis was carried out using a trained panel, and volatile composition of measured using PTR-MS. Twelve cake samples with the largest sensory variation were further selected for consumer testing for perceived freshness. Results demonstrated that sweetener type, fat type, time from baking and their interaction significantly influenced the sensory properties, volatile composition, and perceived freshness of cakes. There was no evidence of perceived freshness segmentation among consumers. Perceived freshness of the twelve cakes not evaluated by consumers was predicted using sensory properties, volatile composition, and their combination. The freshest cakes were evaluated on the day of baking, and contained a combination of margarine and sucrose, and butter and sucrose. The least fresh cakes were evaluated after 15 days of storage and contained a combination of shortening and isomaltose, and butter and isomaltose. The most fresh samples were positively correlated with mass ions m/z 124, 74, 97 and 93, and sensory characteristics of "buttery" odour, and "buttery", "eggy" flavour. The least fresh samples were negatively correlated with mass ions m/z 110 and 95, and sensory characteristics of "rancid", "dusty" and "fatty" odour. Best predictions were obtained for cakes evaluated on day zero that contained a combination of shortening and sucrose. This research established an objective knowledge of consumers' perceived freshness of baked product types in terms of sensory properties and volatile composition. This approach enabled the understanding of ingredients and time from baking influences, as well their interaction on baked product freshness. The predictive models developed that examined relationships between PTR-MS spectra, sensory characteristics and consumer perceived freshness can be applied to predict freshness of baked products not assessed by consumers.

La perception gustative d'un aliment est un phénomène complexe organisé en 3 niveaux d'interactions : les interactions chimiques, physiologiques et cognitives. L'objectif de ce travail est d'étudier les effets de ces 3 niveaux d'interactions sur la perception gustative en passant par l'étude de produits modèles. L'étude des intercations chimiques a permis de montrer que seuls les ions libres sont perçus au niveau gustatif mais avec une large variabilité interindividuelle. L'étude du rôle des interactions physiologiques (mastication, salivation) a permis de montrer que la libération des molécules sapides est un phénomène dynamique étroitement lié à la salivation et à la dégustation. Enfin, la perception gustative et de l'acceptabilité semblent prendre part au contrôle de la mastication en diminuant la durée de celle-ci lorsque l'acceptabilité des produits diminue. Ce travail montre que la saveur des aliments peut être considérablement modifiée par la physiologie orale du dégustateur

L'objectif de ce travail de thèse est d'étudier, au cours de la mastication d'une base fromagère, les relations entre la libération des composés volatils et non-volatils et la perception de la flaveur tout en prenant en compte plusieurs paramètres respiratoires, masticatoires et salivaires. Dans un premier temps, les cinétiques de libération de la plupart des composés volatils et non-volatils présents dans la base fromagère à des concentrations équivalentes à celles observées dans de véritables fromages ont pu être déterminées in vivo. De nombreuses différences interindividuelles ont été observées mais pour un même sujet les profils de libération (de composés volatils ou non-volatils) différaient peu d'un composé à l'autre. La mesure de plusieurs paramètres respiratoires, masticatoires et salivaires a permis d'expliquer une partie des différences interindividuelles observées pour les huit sujets de l'étude et de mieux comprendre le processus de libération des composés responsables de la flaveur de la base fromagère. L'étude concernant la libération des composés d'arôme au cours de la mastication de la base fromagère a été menée en analysant les effluves nasales (méthode dite de nosespace) par deux techniques complémentaires : la SPME-GC-MS et l'API-MS. Nous avons, en particulier, montré l'importance de l'activité des muscles masticatoires, du nombre de cycles masticatoires et de la fréquence respiratoire pour la libération des composés d'arôme. L'étude concernant la libération des composés non-volatils a été menée en analysant des échantillons de salive prélevés à différents temps lors de la mastication, par deux techniques complémentaires : l'HPLC et l'API-MS (échantillonnage en phase liquide). Nous avons montré l'influence du temps de mastication, du flux salivaire, de la fréquence de déglutitions, de la fréquence masticatoire et de l'efficacité masticatoire sur le temps mis pour atteindre la concentration maximale de certains composés non-volatils dans la salive. Dans un deuxième temps, la perception de la flaveur de la base fromagère, (en particulier l'évolution de l'intensité des descripteurs salé, acide, moisi, fruité et rance au cours de la mastication) a été étudiée. Les variations interindividuelles observées ont pu être en partie expliquées par les différences dans les profils de libération des molécules volatiles et non-volatiles en bouche ainsi que par les paramètres de physiologie orale mesurés pour chaque sujet
This study aims to investigate, during eating a model cheese, the relationships between volatile and non-volatile compound release, and flavour perception, taking into account several respiratory, masticatory and salivary parameters. During the first step, the release kinetics of most of volatile and non-volatile compounds whose concentrations in the cheese were similar to those observed in commercial cheeses were determined in vivo. Numerous inter-individual differences were observed but, for each subject, release profiles (of volatile or non-volatile compounds) did not differ from one compound to another. The measurement of several respiratory, masticatory and salivary parameters allowed us to explain some of the inter-individual variations and to better understand the flavour release process from the model cheese. The study of the aroma compound release during eating the model cheese was carried out by analysing the exhaled air from the nose using two complementary techniques: SPME-GC-MS and API-MS. The masticatory muscle activity, the chew number, and the respiratory rate were shown to be very important considering the aroma compound release. The study of the non-volatile compound release was carried out by analysing saliva aliquots sampled at several times during eating using two complementary techniques: HPLC and API-MS (liquid introduction). Chewing time, salivary flow, swallowing rate, chewing rate and masticatory performances were shown to influence the time to reach the maximum concentration of non-volatile compounds in saliva. During the second step, flavour perception - more precisely the intensity changes for salty, sour, mouldy, fruity and rancid attributes - was studied during eating the model cheese. Part of the inter-individual variations could be explained by in mouth flavour release study and by the measured oral parameters

Recent research has shown that food and beverage perception can be influenced by means of aromas, shapes, colours, and even sounds (e.g. Auvray & Spence, 2008; Spence & Piqueras-Fiszman, 2014). Over-and-above any sounds involved in the eating process, various studies have begun to demonstrate the relationship between auditory attributes and taste/flavour perception. This thesis examines crossmodal correspondences - defined as the often-surprising associations between basic attributes of different sensory modalities - between sounds and tastes/flavours. The results reported here demonstrate that participants can make non-random matches between sound and a range of taste/flavour attributes including basic tastes, creaminess, spiciness, and even temperature. Moreover, soundtracks that are congruent with specific taste/flavours are demonstrated to influence food/drink evaluation (the "sonic seasoning" phenomenon). Most importantly, this thesis highlights the multiple pathways by which sonic seasoning might occur. Mirroring the role of food-related auditory cues (such as the sizzle of the steak), soundtracks that can shape our sensory expectations before tasting as well as focus our attention on specific tastes/flavours during tasting. In addition, the emotions evoked by the soundtracks can also be transferred to the food that one happens to be eating. The results are discussed in terms of theoretical implications, practical applications, and directions for future research.

Aroma and texture are known to influence the overall perception of apple flavour and are subconsciously evaluated by consumers during consumption. Aroma is derived from the volatile organic compounds (VOCs) released from the apple both before (orthonasal) and during consumption (retronasal). The degree to which the VOC impacts upon the flavour profile is affected by the mechanical breakdown of the apple flesh during mastication. The characteristics of apple texture, microstructure and breakdown are cultivar specific. This thesis aimed to understand the cultivar specific differences of apple texture, microstructure and VOC release in relation to their role in overall flavour perception and to explore the correlations between sensory derived attributes and instrumental derived parameters. In vitro (orthonasal) and in vivo (retronasal) measurements of VOC release were carried out using either a proton transfer reaction quadrupole mass spectrometer (PTR-QUAD-MS) or a proton transfer reaction time of flight mass spectrometer (PTR-ToF-MS). Both instrumental techniques separated cultivars based on their in vitro headspace volatile organic compound (VOC) profiles of either intact or cut apple portions. However, PTR-ToF-MS was found to be superior to PTR-QUAD-MS due to its higher sensitivity. The in vivo nosespace method involving the measurements of dynamic VOC release from the nasal cavity, during swallowing as panellists consumed apple portions, resulted in improved data and temporal resolution, as well as an increase in the number of detectable nosespace VOCs when the PTR-ToF-MS was used. Ester related VOCs were predominantly detected in the in vivo nosespace measurements followed by carbonyl and alcohol related compounds. Measured nosespace parameters showed potential for use in understanding differences in the mechanical breakdown of apple flesh during mastication; with for example juicy cultivars inducing a faster time to first swallow (Tswal). Panellists also displayed longer consumption times (Tcon) when consuming firm samples, as opposed to softer cultivars. In a preliminary study using the PTR-QUAD-MS, the time to maximum VOC intensity (Tmax) was found to be shorter for soft apple flesh owing to their faster breakdown during mastication and their resulting increase in surface area. However, the PTR-ToF-MS study which used more cultivars suggested that Tmax could also be shorter for firm juicy cultivars, owing to the occurrence of more swallowing events during mastication as juice was released. The feasibility of being able to differentiate between cultivars using solely instrumental techniques was investigated by comparing instrumentally derived results to those gained from descriptive sensory analysis. Sensory odour/ flavour data was compared to VOC profiles obtained from the PTR-ToF-MS, while sensory texture was compared to mechanical and acoustic textural parameters. Both analytical and sensory techniques characterised the cultivars similarly, indicating the potential of solely instrumental techniques to separate apple cultivars based on their VOC profiles and textural properties. Different VOC groups (terpenes; esters and their associated fragments; butanoate esters) were associated to specific sensory attributes. For example, butanoate esters (m/z 103, 117, 131) were positively correlated to lemon flavour and odour whereas hexyl acetate (m/z 145) was positively correlated to overall apple odour signifying its importance towards base apple flavour. Physico-chemical properties such as titratable acidity (TA) were positively correlated to sour taste which could be considered in prediction models. Sweet taste was negatively correlated to TA but was not correlated to soluble solids content (SSC). However, a positive correlation between sweet taste and fruity ester related compounds (m/z 43, 61, 145) was observed indicating a possible aroma-taste interaction. Instrumentally derived texture parameters were well correlated to sensory descriptions. However, the former also provided additional information that could differentiate between cultivars that were firm but not crunchy. As the behaviour of apple flesh breakdown during mastication was shown to affect perceived texture, X-ray micro-computer tomographic (μ-CT) scanning was used to investigate microstructural differences that could affect apple texture. Morphological properties of apple parenchyma such as connectivity and porosity were associated with VOC release, whereas anisotropy was associated with firm texture. Porosity was negatively correlated to firm texture however, this was cultivar specific owing to the fact that porosity is a summation of all intercellular spaces within a volume; it does not take into account the variation in size and distribution which has been shown to affect texture. The use of an ethylene inhibitor, 1-methylcyclopropene (1-MCP) retained the apple texture at a cost of lower VOC emission. However, its efficacy favoured cultivars of high ethylene concentration (Golden Delicious) as opposed to low ethylene emitting cultivars (Fuji). Therefore, it is important to understand the effects of 1-MCP on specific cultivars. This study demonstrated the viable use of PTR-MS and texture measurements to understand the interrelationships between texture and aroma release during consumption. These techniques were shown to characterise apple cultivars similarly to sensory measurements. Moreover, μ-CT scanning proved to be a powerful tool to visualise the role of microstructure in mechanical texture. Overall, these analyses showed that apple cultivars are distinctly different and suggest that such information could be used to compile a database of phenotypes, such as the cultivar specific VOC and texture characteristics. This database could be used as a reference to create high quality apples through careful selection of specific traits in order to create customised apples targeted towards consumer specific needs.

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Este roteiro de Trabalho é parte equivalente de uma análise ARTEMIDIÁTICA do Espaço Urbano, tendo como objetivo principal apresentar os registros visuais elaborados sobre as Reflexões e Análises Perceptivas da Parada Inglesa, um site specific da Zona Norte de São Paulo. A reflexão poética do espaço urbano é apresentada por meio de um roteiro do flanar, na região da Parada Inglesa, a partir de diversos mapas, que foram apropriados por meio de uma leitura gestáltica dos vazios, da construção das linhas às sobreposições temporais, possibilitando assim criar novas interpretações, ou seja, criar uma metodologia de processo artístico, com uma nova linguagem, diferente e semelhante. O trabalho propõe uma reflexão sobre diversas ações realizadas no site specific da Parada Inglesa, analisando como tais procedimentos possibilitam uma reflexão poética do espaço urbano e a percepção artística como instrumento didático metodológico.
This script is part of an ARTEMIDIA analysis of Urban Space, its main objective is to present the visual records elaborated on Cartographic Memories of flâneur in the Parada Inglesa, a specific site of the North Zone of São Paulo. The poetic reflection of the urban space is presented through a guide of the flâneur in the region of the Parada Inglesa from several maps, which were appropriated by means of a gestalt, from the construction of the lines to the temporal overlaps, making possible to create new interpretations, in other words, create another object, a new language, different and similar. The paper proposes a reflection on several actions carried out in the site specific of the Parada Inglesa, analyzing how these procedures allow a poetic reflection of the urban space and the artistic perception as a didactic-methodological instrument.

L’objectif de cette étude est d’étudier l’impact de la fraction volatile odorante et de la fraction non-volatile sur la perception de la flaveur du caramel. Dans la première étape, la fraction volatile du caramel a été analysée par Chromatographie en Phase Gazeuse couplée à l’Olfactométrie (GC/O), par GC couplée à la Spectrométrie de Masse (GC/MS) et par heart-cutting MDGC. Les résultats mettent en évidence une centaine de composés volatils et démontrent la richesse aromatique du caramel. L’objectif de la deuxième étape était d’évaluer la contribution de ces composes volatils à la typicité odorante du caramel. Des études ont montré que l’intensité odorante n’était pas suffisante pour évaluer l’impact des composés. Ce travail de thèse propose une approche originale de recombinaison d’odeur à partir de composés triés selon leur qualité odorante. Les résultats montrent que la typicité odorante caramel est le fruit d’un équilibre entre les notes caramel, fruité, fruits secs, végétal, animal, grillé, floral et piquant. Des tests d’addition, d’omission et d’un plan d’expérience factoriel complet ont démontré l’existence d’interactions perceptives. L’objectif de la dernière étape était d’étudier l’impact de la fraction non volatile sur la perception de la flaveur du caramel. L’étude de la libération de composés d’arôme in vitro par analyses SPME/GC/MS dans différentes matrices non volatiles démontre l’existence d’interactions physico-chimiques entre les composés d’arôme et les macromolécules non volatiles. Ces premiers résultats laissent supposer que la fraction non volatile est susceptible de moduler la perception de la flaveur
The aim of this study was to investigate the impact of the volatile odorant fraction and the non-volatile matrix on the perception of the caramel flavour. The first step focused on the analytical characterization of the volatile odorant fraction of aromatic caramel thanks to Gas Chromatography coupled to Olfactometry (GC/O), GC/Mass Spectrometry (GC/MS) and heart-cutting MDGC/MS/O. Results highlighted the presence of more than one hundred compounds and demonstrated the complexity of the caramel volatile fraction. The objective of the second step was to understand the contribution of odorant compounds identified to the caramel aroma typicality. Literature shows that odour intensity is not sufficient to evaluate the impact of compounds on the aroma. This thesis proposed an original approach to carry out the aroma recombination by taking into account odour qualities. Results showed that the caramel typicality results from a complex balance between caramel, fruity, vegetal, sharp, nutty, floral, roasted and animal odours. Omission, addition tests and a 24 factorial design showed the existence of perceptive interactions. The third step focused on studying the impact the macromolecules that constitute the non-volatile fraction on the perception of caramel flavour. In vitro aroma release was followed by SPME/GC/MS in different matrices varying in non-volatile composition. Results evidence physico-chemical interactions between aroma and macromolecule of the non-volatile fraction. Those preliminary results suggest that the non-volatile matrix is able to impact the flavour perception

La perception rétro-nasale (arôme) lors de la mastication en bouche d’un aliment est un phénomène assez complexe. Les compositions physico-chimique et aromatique du produit, son état physique lors de la mastication en bouche, les interactions et réactions mises en jeu dans la cavité buccale sont autant de paramètres qui peuvent influencer cette perception. Dans le cadre de ce travail la mangue sera utilisée comme fruit modèle. Il s’agira de mieux comprendre l’influence du niveau de déstructuration du produit, de la texture ainsi que de la variabilité inter-individuelle d’un panel d’analyse sensorielle sur la perception de l’arôme. La libération des composés volatils lors de la mastication en bouche in vivo du fruit frais, du fruit en forme de purée et du fruit séché sera étudiée par le dispositif RATD(. Le profil aromatique des produits obtenus par la technique SAFE (Solvent assisted flavor evaporation) et les descripteurs aromatiques établis lors de l’analyse sensorielle seront confrontés avec les données RATD
Retro-nasal perception of flavor during chewing food in mouth is a complex process. The physico-chemical and aromatic compositions of food, its physical properties, the interactions and reactions involved in oral cavity are the main parameters which can influence flavor perception. In this study, mango is used as model fruit. The study will be focused in better understanding of food disintegration effect, its texture and inter-individual variability on the flavor perception. Liberation of volatile compounds during the chewing of fresh fruit, puree fruit and dried fruit will be studied with RATD (Retronasal aroma trapping device). Fruit volatile profile obtained by SAFE (Solvent assisted flavor evaporation) technique and the aromatic descriptors established during the sensory analysis will be compared with the data from RATD analysis

Une approche intégrée physico-chimique et sensorielle a ete mise en oeuvre pour étudier la nature des interactions texture-flaveur dans un produit laitier fermenté aromatisé sans matière grasse de type yaourt brassé.

L'objectif de ce travail est de comprendre les effets d'un changement de composition des modèles fromagers sur la mobilité, la libération et la perception de molécules de la flaveur (sel, composés d'arôme). Six modèles fromagers aromatisés ont été formulés (3 ratios lipides/protéines (L/P) et 2 teneurs en sel). La microstructure et les propriétés rhéologiques des modèles fromagers ont été caractérisées respectivement par microscopie confocale et par compression uniaxiale. La mobilité des ions sodium a été analysée par RMN 23Na. La cinétique de libération des ions sodium a été suivie dans l'eau, puis dans la salive, en situation de consommation. La libération rétronasale des composés d'arôme a été suivie par nose-space APCI-MS, simultanément au suivi des déglutitions, et de la mastication par électromyographie. Enfin, les propriétés sensorielles des modèles fromagers (intensité salée, arôme, texture) ont été étudiées.Une diminution du ratio L/P et une diminution de la teneur en sel diminuent la taille des gouttelettes lipidiques et augmentent la fermeté. Cela conduit à une diminution de la mobilité des ions sodium, qui se traduit par une diminution de la quantité de sodium libéré dans la salive et une diminution de la perception salée. De plus, le maximum de libération d'arôme est atteint plus tard et la perception aromatique est diminuée. Ces effets peuvent être expliqués par la répartition lipides/protéines observée en microscopie, par une déglutition plus tardive et une plus grande activité masticatoire

La nouvelle tendance alimentaire prônant la consommation accrue de protéines végétales est liée aux effets négatifs sur la santé et l’environnement des produits d’origine animale. Pour répondre aux besoins des consommateurs, les industries agro-alimentaires développent ainsi des produits à base de protéines végétales.Parmi les différentes sources de protéines, le pois (Pitsum sativum) présente des avantages environnementaux, technologiques et nutritionnels. Néanmoins, son utilisation dans la formulation de produits reste fortement freinée par la présence de défauts sensoriels qui sont généralement décrits comme étant de type “beany”, “vert” et “végétal”. La fermentation est un des leviers de choix pour modifier la qualité de ces produits.Ce travail de recherche a donc consisté à étudier l’impact de la fermentation sur la perception sensorielle d’un produit type yaourt à base de protéines de pois. Des méthodes microbiologiques, physico-chimiques et sensorielles ont été mises en œuvre.Les molécules responsables des défauts dans la matrice non fermentée ont été identifiées par chromatographie en phase gazeuse couplée à la spectrométrie de masse. Les aldéhydes, en particulier l’hexanal, les furanes, les alcools et les cétones sont les molécules majeures présentes dans cette matrice initiale.Divers microorganismes sélectionnés préalablement ont été cultivés sur cette matrice et leurs capacités d’acidification et d’aromatisation ont été évaluées. Des consortia de bactéries lactiques et de levures ont ainsi été sélectionnés apportant chacun les fonctionnalités recherchées.La modification de la perception des produits fermentés a été mise en évidence par des analyses sensorielles. L’origine de cette amélioration peut être liée à la production d'arômes fruités par les levures et/ou à la dégradation des défauts beany.Afin de mieux comprendre ce phénomène, des analyses sensorielles sur des solutions modèles de molécules cibles (méthodes de recombinaisons et d’omissions) ont été menées. En parallèle, des empreintes moléculaires par chromatographie en phase gazeuse couplée à l’olfactométrie ont été réalisées sur les produits fermentés.Ainsi, les esters produits par les levures ont un rôle déterminant dans l’amélioration de la perception sensorielle des produits fermentés à base de protéines de pois. Concernant les molécules responsables des défauts, l’impact dominant de certaines molécules dont l’hexanal et le 2-pentylfuran a été mis en évidence. Néanmoins, l’impact d’autres molécules de défauts, encore présentes dans la matrice fermentée, reste à approfondir. En particulier, il faudrait déterminer les seuils de perception dans ces matrices et étudier les effets d’interactions.Pour conclure, ce travail de thèse CIFRE nous a permis de déposer un brevet en vue du développement d’un ingrédient innovant, issu de la combinaison d’un procédé de fermentation et de stabilisation par séchage
The new food trend in favor of the increasing consumption of plant proteins is mainly linked to the negative effects of products of animal origin on health and environment. To meet consumers’ needs, agro-food industries are working on the development of plant protein-based products.Among the different sources of proteins, pea (Pitsum sativum) offers environmental, technological and nutritional advantages. However, its use in the formulation of products remains strongly hampered by the presence of off-flavors, described mainly as “beany”, “green” and “vegetable”. Fermentation is one of the means that could be chosen to modify the quality of these products.Therefore, this research consisted of studying the impact of fermentation on the sensory perception of a pea protein yoghurt-like product. Microbiological, physico-chemical and sensory methods were implemented.The molecules responsible for off flavors in the unfermented matrix were identified by gas chromatography coupled with mass spectrometry. Aldehydes, particularly hexanal, furans, alcohols and ketones are the major molecules present in this initial matrix.A variety of preselected microorganisms were cultured on this matrix, and their acidification and aromatization capacities were evaluated. Consortia of lactic acid bacteria and yeasts were selected, based on the desired functionalities that each provides.The modification of the sensory perception of fermented products was confirmed by sensory analyses. The origin of this improvement might be related to the production of fruity aromas by the yeasts and / or the degradation of off-flavors.In order to get a better understanding of this phenomenon, sensory analyses on model solutions of the targeted molecules (recombination and omission experiments) were performed.In parallel, molecular fingerprinting by gas chromatography coupled with olfactometry were carried out on the fermented products.Hence, the produced esters by yeasts played a decisive role in improving the sensory perception of pea protein fermented products. Regarding the molecules responsible for defects, the dominant impact of certain molecules including hexanal and 2-pentylfuran has been highlighted. Nevertheless, the effect of other off-flavor molecules, remaining in the fermented matrix, still needs further exploration. In particular, the perception threshold in these matrices needs to be determined and the interaction effects require exploration.To conclude, this industrial thesis allowed to file a patent pertaining to the development of an innovative ingredient, resulting from the combination of a fermentation process and stabilization by drying

La connaissance de la composition phénolique du Cabernet-Sauvignon (CS) et du Merlot (M) dans la région vitivinicole du bordelais a un intérêt majeur pour définir la structure et la qualité tannique (astringence et amertume) des raisins et des vins. La composition en tanins et anthocyanes de raisins et de vins issus du Cabernet Sauvignon et du Merlot ainsi que leur perception tannique ont été recherchées. L’étude raisins a été réalisée pour cinq parcelles de la région bordelaise (Pauillac, Margaux, Saint Emilion (1), Saint Emilion (2) Côtes de Bourg) pour trois millésimes consécutifs : 2006, 2007 et 2008 et différents types de sol : Limoneux, Sableux, Limono-Sableux 1, Limono-Sableux 2, Limon argilo-sableux pour le M et Limono-argileux, Sablo-limoneux 1, Limono-sableux, Sablo-limoneux 2 et Limoneux pour le CS. Les monomères [(+)-catéchine (C), (-)-épicatéchine (EC), (-)-épicatéchine-O-gallate] et les oligomères (dimères: B1, B2, B3, B4 et trimère Cat-Cat-Epi) des procyanidines, ont été identifiées et quantifiées pour les extraits de raisins (pépins et pellicules) et pour les vins par CHLP-UV-Fluo. Le pourcentage de galloylation (%G), le pourcentage de prodelphinidines (%P) ainsi que le degré moyen de polymérisation (DPm) des tanins oligomères des raisins et des tannins de vin ont été déterminés par CHLP-UV-SM. L’intensité d’astringence et d’amertume des tanins oligomères des raisins (pépins et pellicules) et des vins ont été estimées par analyse sensorielle. Les anthocyanes monoglucosides [cyanidine-3-O-glucoside (Cy), delphinidine-3-O-glucoside (Dp), paeonidine-3-O-glucoside (Pn), malvidine-3-O-glucoside (Mv), petunidine-3-O-glucoside (Pt)] et les anthocyanes acétylées (paeonidine-3-O-glucoside, malvidine-3-O-glucoside) et coumaroylées (paeonidine-3-O-glucoside, malvidine-3-O-glucoside) ont été identifiées et quantifiées par CLHP-UV-SM dans les extraits de pellicules et dans les vins. L’influence du sol, du millésime, et du cépage (pour les raisins et les vins) ont été explorés. Le millésime, dans les deux cas (raisins et vins), a un effet très significatif et domine celui du cépage (raisins et vins) et celui du sol (raisins) sur la plupart des variables étudiées. Selon le type de sol et le millésime, la qualité tannique des raisins est évaluée. Les pépins de CS issus du sol Limono-sableux présentent une grande variabilité au niveau du DPm (3,8 à 7,2) et au niveau du % G (19,0 à 51,3). Ceux-ci sont plus astringents et amers que les pépins issus des autres types de sols. Les pépins (CS) du millésime 2006 sont plus astringents et amers que ceux des autres millésimes, même s’ils sont caractérisés par des valeurs de DPm et % G deux fois moins élevées que ceux de 2007. Pour les sols Limono-sableux, les pellicules (CS) possèdent les valeurs moyennes de DPm (30,89) et de % G (5,07) les plus élevées et sont perçues comme les plus astringentes. Les pépins de M issus du sol Limono-sableux 1 et du sol Limoneux présentent des DPm maximums de 3,20 et 3,03 ; avec des intensités moyennes d’astringence et d’amertume les plus élevées pour le sol Limono-sableux 1. Pour les pépins de M, les intensités d’astringence sont du même ordre pour les 3 millésimes. Les pépins (M) de 2007 possèdent le % G le plus élevé (33,34) et sont perçus plus amers par rapport aux autres millésimes. Les pellicules de M des sols sableux sont plus astringentes avec une variation forte du % P (3,8 à 14,0). Pour le M, les pellicules issues du sol Limoneux sont moins astringentes et se caractérisent par un DPm moins élevé (10,42) par rapport aux autres sols. Pour les pépins, le CS présente un DPm (4,15) et un % G (26,12) plus élevés que celui du M (2,74 et 21,22 %). Pour les pellicules, le CS se caractérise par un DPm (22,85), un % G (3,24 %) et un % P (14,99 %) plus élevés que ceux de M (DPm = 19,42, % G = 1,31 %, % P= 5,54). Pour les trois millésimes étudiés, le cépage n’a influencé ni l'amertume ni l'astringence pour les pépins et les pellicules. Les différences significatives et consécutives sur la composition en anthocyanes entre CS et M pour les trois millésimes portent sur : la Cy, la Pt, la Pn, la Mv et les anthocyanes acétylées et coumaroylées. Les teneurs en anthocyanes acétylées sont deux fois plus élevées pour le CS (6,99 mg/g), alors que le M présente des teneurs en anthocyanes coumaroylées (3,31 mg/g) plus élevées que celles du CS (1,99 mg/g). L’étude de la qualité tannique sur vins, a été réalisée pour 24 millésimes issus de CS et 7 millésimes issus de M. Les teneurs en composés phénoliques, en anthocyanes, en tanins totaux, en monomères des tanins (C+EC), la teinte, l’IC’ (intensité colorante), le % G, le % P et le DPm ainsi que l’intensité de l’astringence apparaissent comme des données pertinentes pour différencier les vins en fonction du millésime. Des corrélations entre l’âge des vins et : le DPm, la teinte, l’astringence, les teneurs en composés phénoliques totaux, en monomères de tanins (C+EC) et en tanins totaux ont pu être obtenues. La caractérisation qualitative des tanins et des vins est établie par corrélation entre l’astringence et le DPm (R2 = 0,509, p = 0,051, CS ; R2 = 0,780, p = 0,000, M). De plus, le DPm apparaît être un marqueur du millésime (R2 = 0,796, p = 0,000 ; CS et R2 = 0,946, p = 0,000 ; M). Nous proposons une échelle reliant le DPm des vins en fonction du millésime et de la perception tannique (astringence). Les vins issus du M sont caractérisés par une moindre richesse en composés phénoliques totaux, en tanins, en anthocyanes, en DPm, en % G, en % P ainsi que par une intensité d’astringence moins importante par rapport a ceux de CS. Le TAV (titre alcoométrique volumique, % vol) semble être positivement corrélé à l’amertume (r = 0,39, p < 0,05)
Cabernet-Sauvignon (CS) and Merlot (M) phenolic composition is of paramount importance to grapes and red wines structure and quality (astringency and bitterness) in Bordeaux winegrowing region. Tannins and anthocyanins composition as well as tannin perception have been studied for Cabernet-Sauvignon and Merlot grapes and wines. Grapes study was carried out with samples from five vineyards located in Bordeaux (Pauillac, Margaux, Saint Emilion (1), Saint Emilion (2)and Côtes de Bourg) for three consecutive vintages (2006, 2007 and 2008) and for different soil types (Silty, Sandy, Silty-sandy 1, Silty-sandy 2, Silty clay-sandy for M and Clay-loam, Sandy-silty 1, Silty-sandy, Sandy-silty 2 and Silty for CS). The proanthocyanidin monomers [(+)-catechin (C), (-)-epicatechin (EC), (-)-epicatechin-O-gallatte] and oligomers [dimers: B1, B2, B3, B4 and trimer Cat-Cat-Epi] from grape extracts (seed and skin) and wine were identified and quantified by HPLC-UV-Fluo. Percentage of galloylation (%G), percentage of prodelphinidins (%P) as well as mean degree of polymerization (mDP) of grape tannins oligomers and wine tannins were determined by HPLC-UV-MS. Sensory analysis concerning astringency and bitterness intensity of grape tannins oligomers (skins and seeds) and wines was also performed. The anthocyanic composition of glucosides [cyanidin-3-O-glucoside (Cy), delphinidin-3-O-glucoside (Dp), paeonidin-3-O-glucoside (Pn), malvidin-3-O-glucoside (Mv), petunidin-3-O-glucoside (Pt)] acetylated glucosides (paeonidin-3-O-glucoside, malvidin-3-O-glucoside]) and coumarylic glucosides (paeonidin-3-O-glucoside, malvidin-3-O-glucoside) of skins extracts and wines were analysed by HPLS-MS. Soil, vintage and grape variety influence on the above parameters are explored. The vintage in both cases (grapes and wines), has a significant effect and dominates that of grape variety (grape and wine) and soil (grape). Depending on soil type and vintage, tannins grapes quality is evaluated. CS seeds from Silty-sandy soil present a great variability on mDP (3.8 to 7.2) and on % G (19.0 to 51.3). The above seeds are more astringent and bitter than those from other soil types. The 2006 seeds (CS) are more astringent and bitter than these from the other vintages, even if they are characterized by G % and mDP values two times lower than these of 2007. Skins (CS) of Silty-sandy soils, have the highest mDP (30.89) and % G (5.07) average values and are perceived as more astringent. M seeds from Silty-sandy 1 and Silty soil have the maximum mDP values (3.20 and 3.03); Silty-sandy 1 M seeds present the highest astringency and bitterness intensities. For M seeds, astringency intensities present the same values for the 3 vintages. The 2007 seeds (M) have the highest % G (33.34) and are perceived bitter than those from the other vintages. M skins from Sandy soils are the most astringent with a strong variation on % P (3.8 to 14.0). M skins from Silty soils are less astringent and are characterized by lower mDP values (10.42) than these from other soils. In seeds, CS presents a mDP (4.15) and a % G (26.12) higher than M (2.74 and 21.22 %). CS skins are also characterized by higher mDP (22.85), % G (3.24 %) and % P (14.99 %) values than M (mDP = 19.42, % G = 1.31 % and %, P = 5.54 %). For all three vintages studied, the grape variety does not affect the astringency and bitterness intensity in both skin and seed tannins extracts. The consistent differences between CS and M for the three vintages on anthocyanin composition are on : Cy, Pt, Pn, Mv, acetylated and coumarylic anthocyanin levels. Acetylated anthocyanins values are two times highest for CS (6.99 mg/g), while M presents (3.31 mg/g) coumarylic anthocyanin levels higher than CS (1.99 mg/g). The study concerning wine tannin quality, was conducted for 24 vintages for CS and for 7 vintages for M. Total phenolic compounds, total anthocyanins, total tannins, tannin monomers (C+EC), hue, IC' (color intensity), % G, % P, mDP and astringency intensity differentiate wines according to vintage. The correlation between wine age and: mDP, hue, astringency, total phenolic compounds, tannin monomers (C+EC) and total tannin levels are obtained. The qualitative tannin and wine characterization is established by correlation between astringency and mDP (R 2 = 0.509, p = 0.051, CS; R2= 0.780, p = 0.000, M). In addition, the mDP appears to be vintage marker (R 2 = 0.796, p = 0.000; CS and R2 = 0.946, p = 0.000; M). Scale patterns between wine mDP and both ageing and tannin perception (astringency) are proposed. M wines are characterized by lower levels of total phenolic compounds, tannins, anthocyanins, mDP, % G, % P % levels as well as by lower astringency intensity than CS wines. Ethanol level seems to be positively correlated to bitterness (r = 0.39, p < 0.05)

The symbolic role of Helena throughout the Byzantine period has never been considered in any detail. Many of the literary sources, particularly historiographical and hagiological texts, are not easily accessible and have not been translated. The visual sources referring to Helena, such as works of late Roman and Byzantine art, coinage, illustrated manuscripts, reliquaries, and wall paintings, have never been collected. My thesis collects and re-evaluates the textual and visual evidence from the fourth to the fifteenth century in order to explore the origins and development of Helena's cult; the emergence of a Helena-legend with symbolic and metaphorical functions; and the ways that the Byzantines reconstructed, judged, and appreciated her role. Special attention is given to the relationship between word and image, as well as the influence exerted on them by contemporary political and social developments. This thesis demonstrates that memories of Helena as an empress and as a saint were manufactured in several distinct stages over several centuries; and that her role differed in the eastern and western halves of the former Roman empire. The evidence is analysed thematically and in chronological order.

L’appréciation du pain par le consommateur est largement impactée par ses propriétés sensorielles, notamment les perceptions d’arômes et de texture en bouche. Ces perceptions ne peuvent pas être uniquement expliquées par la composition aromatique du pain ou par sa structure. Elles dépendent également de phénomènes dynamiques, résultant de la déstructuration du pain en bouche, très dépendante de chaque individu. L’objectif de ce projet de thèse est donc de mieux comprendre les déterminants liés au produit et à l’individu à l’origine des dynamiques de perceptions d’arômes et de texture du pain. Une stratégie multidisciplinaire, basée sur l’étude du processus oral en conditions réelles de mastication, a été mise en place pour répondre à cet objectif. Les résultats de cette étude montrent d’une part que la capacité d’hydratation et la rigidité de la mie jouent un rôle majeur dans l’évolution des propriétés des bols et des perceptions de texture et d’arômes au cours de la consommation. Ainsi, plus un pain a une capacité d’hydratation élevée, plus il sera facilement déstructuré et hydraté. De plus, un pain avec une mie rigide provoquerait une plus grande libération des composés d’arômes susceptibles d’interagir avec les récepteurs olfactifs sensoriels. D’autre part, deux types de comportements masticatoires, basés sur la durée de mastication, ont été identifiés entre les individus participant à l’étude. Ces comportements conduisent à des bols aux propriétés différentes au moment de la déglutition et à des dynamiques différentes de perception de texture et d’arôme
The liking of the bread by the consumers is largely impacted by its sensory properties, and notably the aroma and texture perceived during inmouth consumption. These perceptions cannot be only explained by the volatile composition of the bread or by its structure. In fact, they also depend on dynamic phenomena, resulting from the breakdown of the bread in mouth, which depends on each individual. This PhD project aims thus to better understand the determinants linked to the product and to the individual at the origin of the dynamics of aroma and texture perceptions of bread. A multidisciplinary strategy, based on the study of the oral processing in real conditions of mastication was set up to fulfill this objective. The results show firstly that the hydration capacity and the rigidity of the crumb have a main impact on the evolution of bolus properties and texture and aroma perceptions during consumption. In this way, the higher the hydration capacity of the bread is, the more easily broken and hydrated it will be. Moreover, a bread with a rigid crumb could cause a higher release of volatile compounds susceptible to interact with the sensory olfactive receptors. In addition, two types of masticatory behavior, based on masticatory duration, were highlighted between the individuals of the study. These behaviors lead to bolus with different properties at swallowing time and at different dynamics of aroma and texture perceptions

Afin de rendre les régimes alimentaires occidentaux plus durables, un changement d’alimentation s’impose. Parmi les sources végétales prometteuses, la fèverole (Vicia faba L.) peut être utilisée comme ingrédient à fort potentiel nutritionnel et fonctionnel dans la formulation de produits alimentaires. Les graines de fèveroles sont transformées en ingrédients, qui peuvent à leur tour être modifiés, fonctionnalisés, afin d’être plus adaptés à des applications alimentaires. Ce travail de thèse avait pour objectif de comprendre le rôle des conditions de transformation des ingrédients riches en protéines de fèveroles sur leurs propriétés fonctionnelles et leur flaveur. L’impact des conditions de transformation, choisies pour être réalistes sur le plan industriel, a été étudié en utilisant une approche multi-dimensionnelle et trouver ainsi un compromis favorable à l’expression des propriétés des différents ingrédients. Plus précisément, un concentrât de fèveroles riche en protéines, traité selon un procédé de transformation doux à l’échelle industrielle, a été sélectionné puis modifié par différentes conditions de transformation, i.e. le pH (2, 4, 6,4 et 11), la température (55, 75 et 95 °C) et la durée du traitement (30 et 360 min). Trente-six ingrédients différents ont ainsi été produits. Ceux-ci ont ensuite été utilisés à deux pH différents, 4 et 7, dans des systèmes modèles proches d’applications de type boissons. Au cours de l'utilisation de ces ingrédients, la fonctionnalité des boissons (propriétés moussantes et émulsifiantes), la perception olfactive des produits et la composition en composés volatils et non volatils ont été étudiées. Les résultats montrent que les conditions de transformation sont capables de moduler les propriétés fonctionnelles et olfactives du concentrât de fèveroles, l’analyse étant renforcée par le biais de différents modèles statistiques. Les propriétés des mousses et des émulsions sont principalement gouvernées par le pH d'utilisation des ingrédients. Un pH proche du point isoélectrique des protéines de fèverole (pH 4) n'est pas favorable ni à la stabilité de la mousse, ni à la capacité d’émulsification ou à la stabilité de l'émulsion. Des corrélations entre les propriétés fonctionnelles et les propriétés physico-chimiques ont été mises en évidence et s’expliquent par les propriétés des protéines. Par ailleurs, la flaveur est fortement influencée par les conditions de modification et d'utilisation des ingrédients, en particulier par le pH. Selon les modifications du concentrât initial, en conditions douces ou sévères, la perception peut être modifiée, pour évoluer d’odeurs vertes à des odeurs cuites, tandis que les conditions d'utilisation des ingrédients (pH) peuvent conduire à des perceptions « douces » ou rances. La composition en composés volatiles de l’espace de tête des ingrédients mis en suspension montre la présence de nombreux aldéhydes et alcools. L'oxydation des lipides apparaît importante dans la génération de composés volatiles, de même que des réactions de dégradation des protéines, des sucres et des caroténoïdes. Les propriétés physico-chimiques et sensorielles des composés à l’origine du potentiel antioxydant, du goût (amertume et astringence), de la couleur et des effets antinutritionnels ont également été étudiés. Les composés phénoliques et les saponines se sont avérés significativement impactés par les conditions de transformation mises en œuvre lors de la modification des ingrédients, en particulier par le pH. Les profils en composés phénoliques et en saponines obtenus à l’issue des traitements acide et alcalin (pH 2, 4 et 11) apparaissent ainsi très distincts de celui obtenu par un traitement effectué sans ajustement de pH (pH 6,4). Des études complémentaires menées à pH 6,4 indiquent que cette différence serait liée à une question d’extractibilité variable des composés étudiés et/ou à une réactivité plus ou moins élevée selon les conditions de transformation
The growing population is demanding new healthy, sustainable solutions for foods and beverages. Fava bean (Vicia faba L.) is a promising plant source that can provide nutritional and functional ingredients for different food applications. Fava bean is processed to form ingredients and they can be further modified to render them fit for food applications. This PhD work aimed to understand the role of processing conditions on functional and flavor properties, and apply this understanding to produce and use fava bean protein-rich ingredients. It investigated the effects of certain industrially relevant process conditions using a cross-dimensional approach to find the right kind of compromise between different ingredients properties. To be precise, a very gently processed fava bean protein rich concentrate was industrially procured, which was then modified by process conditions such as pH (2, 4, 6.4 and 11), temperature (55, 75 and 95 °C) and treatment duration (30 and 360 min) to produce 36 different ingredients. These were further utilized at two pH (4 and 7) in systems close to beverage applications. During ingredient utilization, beverage functionalities (foam and emulsion) along with odor perception and non-volatile compounds were investigated for all ingredients as a function of process conditions.Results showed that process conditions were able to drive functional and flavor properties of the fava bean concentrate, strengthened by different statistical models. Foam and emulsion properties were predominantly governed by the pH during ingredient utilization. In general, utilization pH around the isoelectric point of fava proteins (pH 4) was not suitable for foam stability, emulsion capacity nor emulsion stability. Strong correlations between functional and physico-chemical properties were identified and explained by protein properties. In addition, flavor was heavily driven by the modification and utilization conditions, especially the pH.From gentler to vigorous process conditions, perception can be modified from more green to more cooked flavors, whereas different conditions of application (e.g. pH) can modulate between “sweet” and rancid perceptions. Considering volatiles composition, aldehyde signals were primarily detected in ingredient suspensions head-space. But furanoids, terpenoids, alcohols and ketones signals had the next higher contribution for modifications at pH2, 4, 6.4 and 11 respectively. Lipid oxidation was deemed important in generating volatiles, along with other reactions including proteins, sugars and carotenoids degradation. Going deeper into understanding of physico-chemical and sensory properties, determinants of antioxidant potential, taste (bitterness and astringency), color and even anti-nutritional effects were also investigated. Phenolic compounds (flavan-3-ols, flavones, flavonols, hydroxycinnamic acids) and saponins were significantly impacted by process conditions during ingredient modification, especially by pH. For phenolic compounds, acidic and alkaline conditions (pH 2, 4 and 11) were highly distinct compared to the non-pH adjusted process (pH 6.4) in changing the phenolic and saponin profiles of the ingredients. When looked closely at non-pH adjusted processes, their variability due to increasing degree of processing seemed to be either a function of their variable extractability and/ or their reactions involving their structural rearrangement.Thus, process conditions played an important role in fava bean ingredient properties, and this work opens up new arena for inter-disciplinary study based on nutritional (anti-oxidant and anti-nutritional aspects), sustainability (life cycle assessment), functionality (gelation) and sensory (texture, sweetness, bitterness) considerations of fava bean as potential ingredients for industrial food applications

Notre travail a porté sur la caractérisation instrumentale et sensorielle de la texture d'une gamme de produits modèles de types fromages fondus. Trois objectifs ont guidé cette thèse. Le premier objectif était d’utiliser une approche individuelle qui prenne en compte la diversité de perception, de manipulation et de description des panélistes pour la caractérisation sensorielle. De plus, pour étudier l'effet d’expertise préalable, deux panels ont évalué les produits : des consommateurs et des experts. Une approche combinée de deux méthodologies différentes avec deux différents types de verbalisation (Description libre suivi par un Profil Flash) a permis d’identifier des spécificités dans la façon de répondre des deux panels. La description libre a montré les similitudes et les différences entre les terminologies des deux panels. Elle a montré que les experts produisent en moyenne plus de termes que les consommateurs. Cependant, certains de leurs termes sont spécifiques et n'ont jamais été cités par les consommateurs. Le Profil Flash a montré qu'il y a quelques caractéristiques qui deviennent importantes lorsque les panélistes évaluent l’ensemble des produits simultanément. Le résultat a montré des différences importantes entre les cartes produites des consommateurs et des experts issues de la méthode de Description libre. Cependant, les cartes sensorielles obtenues après le Profil Flash étaient très semblables pour les deux panels et proche de la carte obtenue pour le jury de consommateurs avec la méthode de Description libre. Quelques attributs spécifiques ont été fréquemment cités pour des évaluations de produits par les deux méthodes appliquées, comme le terme "Collant".Le deuxième objectif était d'établir une évaluation instrumentale des produits sur la base des résultats sensoriels pour ainsi mieux déterminer des méthodes et conditions pertinentes de caractérisation en regard des perceptions identifiées. Nous avons donc utilisé les descriptions et observations de mesures sensorielles pour choisir des méthodes instrumentales appropriées. Sur cette base, des méthodes rhéologiques classiques (mesures de propriétés viscoélastiques et pénétrométrie) et une mesure de tack adaptée ont été utilisées pour la caractérisation des produits. De plus, les produits ont été caractérisés dans deux états physiques (sans ou après un traitement mécanique important). La méthode de tack adaptée et la rhéologie aux petites déformations avec une géométrie à ailette ont permis de caractériser l'ensemble des produits présentant pourtant une diversité importante de texture (solide, semi-solide, liquide). Les résultats ont montré que la combinaison des deux méthodes améliore la représentation de l’espace produits et qu’elle apporte de nouveaux axes de description. La caractérisation instrumentale sur des produits traités mécaniquement n'a pas amené à une configuration sensiblement différente des produits.Le troisième objectif était de prévoir le positionnement sensoriel de produits (la carte de produit) et plus particulièrement la perception spécifique de certains attributs comme "Collant", à partir des mesures instrumentales. Une prédiction plutôt satisfaisante de la perception des produits par le jury de consommateurs est obtenue à partir des mesures de propriétés viscoélastiques en dynamique (module conservatif et seuil de contrainte) et des paramètres issus du test de tack (énergie totale et distance à la force maximale). De plus, la perception sensorielle du terme «collant » est bien prédite par le paramètre instrumental seuil de contrainte pour la majorité de consommateurs qui ont utilisé ce terme dans leurs évaluations
In our study the texture of a set of model processed cheeses is characterized through both sensory and instrumental approaches. Three objectives guided our work. The first was using an individual approach that takes the diversity in terms of perception, manipulation and description into account for sensory characterization of products. Furthermore, to study the effect of prior expertise, two panels evaluated the products: consumer and expert panel. A combined approach with two different methodologies and verbalization (Free comment followed by Flash Profile) made it possible to identify specificities in the answer behavior between the two panels. Free comment showed the similarity and differences between the terminologies of two panels. It showed that experts generate more terms in average than consumers. However, some of their terms are specific and never was cited to consumers. Flash profile showed that there are some characteristics that become important once the assessors evaluate the products simultaneously. The result showed important differences between the resulted product maps from consumers and experts after free comment method. However, the resulted sensory maps after the Flash Profile were very similar for both panels and were close to the sensory map obtained for consumer panel after free comment. Some specific attributes were frequently cited for products evaluations in two applied methods, such as “Collant (Stickiness)”.The second objective was to establish the instrumental characterization on the basis of sensory results in order to better determine some efficient methodologies and conditions to characterize the identified perceptions. We thus used sensory descriptions and observations to choose appropriate instrumental methods. On this basis, classic rheological methods (measurement of the viscoelastic properties and penetrometry) and adapted tack method were used for product characterization. Furthermore, the products were characterized at two physical states (without or after a mechanical treatment). The adapted tack method and the rheology at small deformation with vane geometry permitted to characterize the products set with important texture diversity (solid, semi-solid, liquid). The results showed that the combination of two methods improves the product map and brings new axes of description. The instrumental characterization of mechanically treated products did not lead to a rather different products configuration.The third objective was to predict the sensory positioning of products (product map) as well as the specific multidimensional perception “Collant (Stickiness)”, by instrumental measurements. A rather satisfactory prediction of consumer perception of texture was obtained through viscoelastic measurements (storage module and yield stress) and parameters stemming from tack measurement (total energy and distance at maximum tensile force). Furthermore, the sensory perceptions relative to “Collant (Stickiness)” is well predicted by the instrumental parameter “yield stress” for the majority of the consumers who applied this term in their evaluations

L'objectif de cette thèse est d'étudier les différents types de connaissances et de compétences impliquées dans l'expertise du vin. Ce travail s'appuyant sur le concept de vin de garde, nous avons dans un premier temps approfondi l'étude de ce concept et nous avons identifié des indices gustatifs (astringence et acidité) et olfactifs (notes boisé, brûlé, vanillé et pruneau) utilisés par les professionnels bourguignons du vin pour évaluer le potentiel de garde de vins rouges de Bourgogne. L’étude de l’expertise s’est articulée autour de deux études. Dans la première étude, nous avons testé si l’environnement dans lequel les professionnels exercent leur activité entraîne des différences au niveau de leurs compétences perceptives et de leurs connaissances relatives au vin de garde. Nous avons montré que des professionnels bourguignons et bordelais sont globalement en accord pour catégoriser des vins de Bourgogne et de Bordeaux en vin de garde et de non garde. Cependant, les professionnels d’une région semblent plus en accord pour juger qu’un vin de leur région est de garde comparativement aux vins de l’autre région. Ceci pourrait indiquer que la familiarité intervient dans les jugements du potentiel de garde. Dans la deuxième étude, nous avons examiné comment les compétences perceptives, les connaissances conceptuelles, le contenu lexical et le statut des connaissances s’articulent chez des professionnels du vin, des œnophiles, des consommateurs de vin et des panélistes entraînés à décrire des vins. Nous avons montré que ces différents aspects se manifestent de manière différentielle selon le type d’expertise : les œnophiles utilisent un discours conventionnel et normatif comme les professionnels, les panélistes utilisent un lexique proche des professionnels, mais les œnophiles comme les panélistes sont similaires aux consommateurs quand des compétences perceptives et des connaissances conceptuelles en référence au vin de garde sont nécessaires. Les professionnels et les œnophiles s’identifient comme appartenant à une communauté qui partagerait les mêmes connaissances et représentations. Leurs connaissances sont également plus certaines que celles des panélistes et des consommateurs. Une dimension intéressante pour l’étude de l’expertise semble émerger : le statut partagé et assuré des connaissances
This work aimed to investigate different types of knowledge and skills involved in wine expertise. This work is based on the “vin de garde” concept, we first broadened the study of this concept, and we identified gustatory (astringency and acidity) and olfactory (woody, burnt, vanilla and prune notes) clues used by wine professionals from Bourgogne to judge the aging potential of red wines from Bourgogne. The expertise is investigated through two studies. In the first study, we examined if the environment in which professionals practise leads to specific perceptive skills and conceptual knowledge regarding wines with an aging potential. We showed that overall professionals from Bourgogne and Bordelais are in agreement to categorize wines from Bourgogne and Bordeaux in “vin de garde” and “vin de non garde”. However, their judgements regarding aging potential seem more consensual for wines from their own area compared to wines from the other area. This could indicate that familiarity is involved in aging potential judgments. In the second study, we examined how perceptive skills, conceptual knowledge, lexical content and knowledge status are combined for wine professionals, oenophiles, wine consumers, and panelists trained to describe wines. We showed that these different aspects are combined according to the type of expertise: oenophiles use a conventional and normative discourse like professionals, panelists use a lexicon similar to professionals, but oenophiles and panelists are similar to consumers when perceptive skills and conceptual knowledge in reference to wine with an aging potential are required. Professionals and oenophiles consider themselves as belonging to a community with shared knowledge and representations. Their knowledge is also more certain than that of panelists and consumers. An interesting aspect for the study of expertise emerges: the shared and sure status of knowledge

La plupart des composés volatils connus et impliqués dans les mécanismes de l’expression fruitée des vins rouges sont présents à des teneurs inférieures ou proches de leurs seuils de perception individuels. Compte tenu de phénomènes d’interactions perceptives entre eux, il est très complexe de déterminer leur impact réel sur l’arôme du vin. Au vu des difficultés rencontrées pour reconstituer fidèlement l’arôme des vins à partir uniquement de composés purs, nous avons développé une méthodologie permettant d’aborder cette reconstitution aromatique à partir de fractions issues du vin lui-même, afin de pouvoir évaluer l’importance relative de ces différentes fractions aromatiques vis-à-vis de l’arôme global du vin. Grâce à l’analyse sensorielle, et en s’attachant à quelques descripteurs particuliers, nous avons pu mettre en évidence, quelques interactions perceptives particulières comme des effets de contributions marquées ou de masquage. La caractérisation des composés présents dans les fractions concernées et à l’origine de ces effets notables a été mise en œuvre. Nos résultats soulignent le rôle indirect du 2-hydroxy-4-méthylpentanoate d’éthyle, un ester éthylique élué dans la fraction à l’origine d’une contribution marquée aux notes de fruits noirs frais qui, en provoquant la diminution du "seuil de perception" du pool fruité des vins rouges et l’augmentation de l’intensité de leurs notes de fruits noirs et de fruits frais, agit comme un exhausteur naturel de ces notes fruitées. Nous sommes aussi parvenus à mettre en évidence, le rôle direct du diacétyle, mais aussi le rôle indirect de l’acétoïne, de l’acide acétique et de la γ-butyrolactone, malgré leurs concentrations infraliminaires, sur la diminution de l’intensité globale et l’intensité du caractère de fruits frais. Ces résultats soulignent leur fort caractère, seuls ou en mélanges, de "réducteurs" de l’intensité de ces notes, et ce, même à des concentrations infraliminaires. Enfin, le comportement particulier, au sein d’un mélange fruité, du 3-hydroxybutanoate d’éthyle, de l’acétate de 2-méthylpropyle, du propanoate d’éthyle et de l’acétate de butyle, présents à des concentrations infraliminaires a été mis en évidence. La présence en mélange des deux premiers provoque la baisse notable du "seuil de perception" du pool fruité et celle des trois derniers augmente l’intensité des notes de fruits frais et fruits noirs traduisant l’effet exhausteur d’arômes dû à ces composés, effet comparable de celui du 2-hydroxy-4-méthylpentanoate d’éthyle qui présente quelques analogies structurales avec ces composés
Most of volatiles involved in red wines’ fruity expression are present at levels below or close to their individual perception thresholds. Given the existence of perceptive interactions between them, it is very difficult to determine their real impact on wine aroma. Rather than assessing the olfactive behavior of mixtures prepared from pure products, the main goal of this work was to highlight and study the impact of perceptive interactions on wine fruity aroma expression using various aromatic reconstitutions prepared from wine fractions. Sensory profile analyses identified significant differences among aromatic reconstitutions for the intensity of some descriptors, as particular "additive" or "masking" effects. The composition of the involved fractions was then studied by instrumental methods. The final target was to investigate the impact of fraction components on fruity aroma by preparing aromatic reconstitutions and using sensory reconstitution tests, to assess the role of these compounds on the perceptive interactions previously observed. Further analysis revealed that ethyl 2-hydroxy-4-methylpentanoate, eluted in fraction which had an "additive" effect on the black-berry and fresh fruity aroma, does not play a direct role as a key compound in red wine aroma. In contrast, our findings highlighted its indirect contribution to wine aroma, showing that this ester contributed to a synergistic effect, enhancing the perception of fruity character. Finally, it was clearly demonstrated that this compound acts as a natural enhancer for black-berry and fresh fruit notes in red wine. It was also established that diacetyl, acetoin, acetic acid and γ-butyrolactone together played the same hypo-additive role as fractions of which they were eluted, presenting a "masking" effect on fresh fruity aroma. The impact of the last three compounds was demonstrated conclusively, even at subthreshold concentrations. These findings highlighted the existence of new remarkable perceptual interactions impacting overall and fresh-fruit aroma perception. The particular behavior, in a fruity mixture, of ethyl-propanoate, ethyl-3-hydroxybutanoate, butyl acetate and 2-methylpropyl acetate, present at subthreshold concentrations, was demonstrated. The presence of ethyl-3-hydroxybutanoate and 2-methylpropyl acetate in mixture led to a significant decrease of the olfactory threshold of fruity pool confirming their synergistic effect in the overall increase intensity. These compounds with close chemical structures, participate, both quantitatively and qualitatively, in the modulation of red wines’ fruity aromas acting as natural enhancers of black-berry and fresh-fruit aromas

L’agrément d’un vin dépend du jugement de ses qualités organoleptiques par un jury de professionnels. Les performances olfactives et gustatives nécessaires des dégustateurs y jouent un rôle déterminant. Pourtant jusqu’ici, ces aptitudes sensorielles fondamentales n'étaient pas directement prises en compte par les professionnels. Même si l’on peut donner une définition de l'expert, en préciser les capacités nécessaires, de multiples études ont mis en relief l’hétérogénéité des appréciations individuelles de dégustation et le manque de consensus forts. La littérature illustre les différences d’expertises entre professionnels et novices, mais aucune étude ne s’intéresse à l’amplitude des différences sensorielles interindividuelles chez les experts.Nos recherches nous ont conduit à caractériser les capacités olfactives de la population des professionnels du vin et à mesurer leur influence sur l’appréciation d’un vin. Nos mesures ont montré la variété interindividuelle des capacités perceptives, des appréciations hédoniques et des capacités cognitives recrutées par le traitement de l’information olfactive chez les professionnels du vin. Nos expériences ont suggéré que ces différences interindividuelles, relatives notamment à la sensibilité et l’appréciation hédonique, influencent la perception et le jugement d’un même vin par les experts. Cependant les résultats confirment aussi la possible influence de la dimension cognitive liée au vécu du sujet sur la perception olfactive plus ou moins complexe et l’apprentissage olfactif. Finalement, ce travail permet de déterminer des besoins en formation. Nous proposons en conséquence des outils pratiques d’évaluation des capacités sensorielles et des pédagogies d’entraînement adaptées. C'est l'occasion de souligner la pertinence de certains facteurs cognitifs dans l’amélioration des performances olfactives, tels que ceux impliquant l’attention ou l'imagerie mentale olfactives
The quality of a wine is measured primarily by experts who evaluate its organoleptic features. Their olfactory and gustatory capacities are decisive, but these experts do not appreciate their own sensory abilities. Moreover, although we can give a clear definition of the expertise, several studies have shown that professionals are often confronted with disparities in their wine assessment. Several studies have also shown the differences between experts and novices, but no attention was paid to the diversity of the chemosensory abilities of the experts.At the Oenology Faculty in Bordeaux, with voluntary participation of the professionals, we characterized the olfactory performances of wine professionals and measured their impact on the wine assessment.The results showed significant inter-individual variation in olfactory sensitivities, hedonic ratings and cognitive abilities among the wine professionals. Further, our experiments have suggested that these inter-individual differences, especially concerning the sensitivity and the hedonic appreciation, influence perceptions and judgments of a same wine by the experts. However, the results confirm the possible influence of the cognitive dimensions related to the experience of the subject on their perception and their olfactory training. Finally, this work identifies training needs. We therefore propose and test practical tools for assessment of sensory performances and appropriate sensorial training. This has been an opportunity to highlight the potential role of attention or olfactory mental imagery in the improvement of the olfactory performance