Academic literature on the topic 'Flavor and odor'

Peach is an edible, sweet, juicy fruit and is widely consumed throughout the world. Peach flavor is a very sweet and delightful fruity flavor which can be used in many products. Therefore, developing a peach flavor is of significant interests. This article deals with developing a fresh peach flavor. According to the odor peach fruit, the notes of peach were identified. Proper chemical ingredients were selected to imitate the odor of peach and to create a peach flavor. A fresh peach flavor formula was obtained. The functions and the odors of raw materials in the peach flavor were discussed. The peach flavor obtained is of fresh harmonious peach odor and is very similar to the odor of natural peach fruit.

Flavor perception arises from the central integration of peripherally distinct sensory inputs (taste, smell, texture, temperature, sight, and even sound of foods). The results from psychophysical and neuroimaging studies in humans are converging with electrophysiological findings in animals and a picture of the neural correlates of flavor processing is beginning to emerge. Here we used event-related fMRI to evaluate brain response during perception of flavors (i.e., taste/odor liquid mixtures not differing in temperature or texture) compared with the sum of the independent presentation of their constituents (taste and/or odor). All stimuli were presented in liquid form so that olfactory stimulation was by the retronasal route. Mode of olfactory delivery is important because neural suppression has been observed in chemosensory regions during congruent taste–odor pairs when the odors are delivered by the orthonasal route and require subjects to sniff. There were 2 flavors. One contained a familiar/congruent taste–odor pair (vanilla/sweet) and the other an unfamiliar/incongruent taste–odor pair (vanilla/salty). Three unimodal stimuli, including 2 tastes (sweet and salty) and one odor (vanilla), as well as a tasteless/odorless liquid (baseline) were presented. Superadditive responses during the perception of the congruent flavor compared with the sum of its constituents were observed in the anterior cingulate cortex (ACC), dorsal insula, anterior ventral insula extending into the caudal orbitofrontal cortex (OFC), frontal operculum, ventral lateral prefrontal cortex, and posterior parietal cortex. These regions were not present in a similar analysis of the incongruent flavor compared with the sum of its constituents. All of these regions except the ventrolateral prefrontal cortex were also isolated in a direct contrast of congruent − incongruent. Additionally, the anterior cingulate, posterior parietal cortex, frontal operculum, and ventral insula/caudal OFC were also more active in vanilla + salty minus incongruent, suggesting that delivery of an unfamiliar taste–odor combination may lead to suppressed neural responses. Taken together with previous findings in the literature, these results suggest that the insula, OFC, and ACC are key components of the network underlying flavor perception and that taste–smell integration within these and other regions is dependent on 1) mode of olfactory delivery and 2) previous experience with taste/smell combinations.

Aroma is one of the most important quality indicators of tea. However, this evaluation method is a subjective one. In this study, the volatiles of tea with 5 types were determined by headspace solid-phase micro-extraction (HS-SPME) combined with gas chromatography mass spectrometry (GC-MS). The aroma intensity and odor characteristics of teas were comparatively analyzed based on the OAV-splitting method. The results showed that OAV were green tea (492.02), red tea (471.88), oolong tea (302.74), white tea (68.10), and dark tea (55.98). The odor index I(o) indicated that green tea was strong-flavor tea with highlight green accompanied by fruity, woody and fatty odors; oolong tea was strong-flavor tea with fruity and fatty accompanied by woody, floral and green odors; red tea was strong-flavor tea with highlight fruity accompanied by woody, green and floral odors; white tea was a light-flavor tea with floral, woody and green odors; and dark tea was light-flavor tea with woody and floral notes accompanied by fatty and green odors. These results fitted perfectly with the people’s consensus on these teas, and proved that the OAV-splitting method is feasible to evaluate the aroma intensity and odor characteristics of tea aroma. We suggest that the digital evaluation of tea aroma can facilitate people’s communication.

Sensory profiles for several ewe’s milk cheeses were developed and main sensory differences evaluated using a specifically designed methodology. It was stated that the existence of several clearly defined groups of sensory terms were negatively correlated. One group consisted of the attributes odor intensity, sharp odor, brine odor, rennet flavor, and butyric acid flavor. The other group consisted of milky odor, toasty odor, buttery odor and flavor, nutty flavor, and sweet flavor. Results pointed out that every descriptor except surface roughness showed a significant difference ( p< 0.01) among the samples. Main sensory differences were basically attributable to different manufacturing technologies as well as different ripening periods.

Flavor-profile analysis (FPA) is a sensory method utilizing a trained panel of four to six individuals. Reference materials are used to establish a common vocabulary for different odors found in drinking water. Known quantities of different taste- and odor-causing chemicals are evaluated to calibrate the panel on a consistent intensity scale. Each identifiable descriptor is assigned its own intensity. This method has been successfully applied in the analysis of musty-smelling compounds, e.g., 2-methylisoborneol (MIB). MIB samples and standards from 1 to 80 ng/l have been shown to observe the WeberFechner law (i.e., a plot of flavor intensity versus logarithm of concentration of MIB yielded a straight line). FPA has also been used to handle fishy/swampy odor problems. In many instances, specific causative organic compounds were not identified; however, FPA evaluations of water using different free-chlorine dosages and contact times made possible immediate resolution of these odor problems. FPA has yielded reproducible sensory data that have been useful in better understanding and handling off-flavors in drinking water.

Abstract. Diversification of patin fish macaroni has the weakness of fish’s dominating flavor, so it requires a variety of flavor fortifications on patin fish macaroni to overcome these problems. This study was aimed to determine the effect of fortification flavors on macaroni catfish (Pangasius hyphophthalmus) on consumer acceptance. The method used is the experiment of making macaroni catfish with cheese, spinach, and barbeque. This study used a completely randomized design with 4 treatments and 3 replications. The treatments that M0 (control), M1 (cheese 50 grams), M2 (spinach 50 grams), M3 (barbeque 50 grams). The results of this study showed that the addition of three flavor had been varying levels of consumer acceptance, namely for panelists who liked the appearance of M0 63 people (78.75%), flavor 82.56%, odor 86.25%, texture 75%; panelists who liked the appearance of M1 80%, flavor 88.75%, odor 88.75%, texture 73.75%; panelists who liked the appearance of M2 85%, flavor 93.75%, odor 93.75%, texture 76.25%; and M3 that liked the macaroni appearance 80%, flavor 71.25%, odor 61.25%, and texture 75%. The most preferred macaroni by panelists based on the organoleptic test was macaroni with added flavor of spinach (M2), which is characterized by greenish yellow, the odor and flavor of slightly fishy, dominant spinach flavor, and hard texture. The proximate composition of M2 was a water content of 12.24%; protein of 14.67%; fat of 1.42%; crude fiber 0.34%.Keywords: Flavor; fortification; macaroni; patinAbstrak. Diversifikasi makaroni ikan patin memiliki kelemahan flavor ikan yang mendominasi, sehingga diperlukan fortifikasi aneka flavor pada makaroni ikan patin untuk mengatasi permasalahan tersebut. Penelitian ini bertujuan untuk menentukan pengaruh fortifikasi aneka flavor pada makaroni ikan patin (Pangasius hypophthalmus) terhadap penerimaan konsumen. Metode penelitian yang digunakan yaitu melakukan percobaan pembuatan makaroni ikan patin dengan fortifikasi tiga macam flavor yaitu keju, bayam dan barbeque. Rancangan percobaan pada penelitian ini adalah Rancangan Acak Lengkap dengan 4 perlakuan dan 3 kali ulangan yaitu M0 (kontrol), M1 (keju 50 g), M2 (bayam 50 g), M3 (barbeque 50 g). Hasil penelitian menunjukkan bahwa fortifikasi tiga macam flavor memiliki tingkat penerimaan konsumen bervariasi yaitu untuk panelis yang menyukai M0 terhadap rupa 78,75%, rasa 82,56%, aroma 86,25%, tekstur 75%; panelis yang menyukai M1 terhadap rupa 80%, rasa 88,75%, aroma 88,75% dan tekstur 73,75%; panelis yang menyukai M2 terhadap rupa 85%, rasa 93,75%, aroma 93,75% dan tekstur 76,25%; dan untuk perlakuan M3 yang menyukai rupa makaroni 80%, rasa 71,25%, aroma 61,25% dan tekstur 75%. Makaroni yang paling disukai oleh panelis berdasarkan penilaian organoleptik adalah makaroni dengan penambahan flavor bayam (M2) yaitu dengan karakteristik berwarna kuning kehijauan, sedikit aroma dan rasa ikan, dominan rasa bayam, dan tekstur yang keras. Komposisi proksimat M2 yaitu kadar air 12,24%; kadar protein 14,67%; kadar lemak 1,42%, serat kasar 0,34%.Kata kunci: Flavor, fortifikasi, makaroni, patin

Smell, which allows us to gather information about the hedonic value of an odor, is affected by many factors. This study aimed to assess the relationship among individual factors, odor sensitivity, and enjoyment, and to evaluate how overall flavor perception and liking in actual food samples are affected by odor sensitivity. A total of 749 subjects, from four different Italian regions, participated in the study. The olfactory capabilities test on four odors (anise, banana, mint, and pine), as well as PROP (6-n-prpyl-2-thiouracil) status and food neophobia were assessed. The subjects were clustered into three groups of odor sensitivity, based on the perceived intensity of anise. The liking and intensity of the overall flavor were evaluated for four chocolate puddings with increasing sweetness (C1, C2, C3, and C4). The individual variables significantly affected the perceived intensity and liking of the odors. Even if all of the odor sensitivity groups perceived the more intensely flavored samples as the C1 and C4 chocolate puddings, the high-sensitivity group scored the global flavor of all of the samples as more intense than the low-sensitivity group. The low-sensitive subjects evaluated the liking of the sweeter samples with higher scores than the moderate-sensitive subjects, whereas the high-sensitive subjects gave intermediate scores. In conclusion, odor sensitivity plays a pivotal role in the perception and liking of real food products; this has to be taken into account in the formulation of new products, suitable for particular categories with reduced olfactory abilities.

Yellow glutinous rice wine is a traditional Chinese beverage created by soaking, boiling, and fermenting glutinous rice. The majority of current studies on the flavor of yellow glutinous rice wine are based on instrumental analysis, with sensory analysis being overlooked. In this study, 36 volatile chemicals in the fermentation process of yellow wine were annotated by GC-MS and then an OPLS-DA model was built to screen out 13 distinctive substances (VIP > 1, p < 0.01). The relative odor activity value (ROAV) was calculated using the threshold values of these chemicals and 10 substances, including alcohols, esters, and aldehydes, were found as key contributors to the overall flavor of yellow wine. Following that, consumers quantified the sensory descriptors of yellow wine using rate-all-that-apply (RATA), and correspondence analysis revealed three groups of characteristic flavors and odors. Alcohols and esters were found to be key producers of flowery and fruity scents in yellow wine, according to correlation analysis. We discovered two alcohols that are rarely found in yellow wine: [R,R]-2,3-butanediol and 1-phenylethanol. The former was found to be favorably connected with wine scent and pungent odor, and its specific effect on flavor should be researched further.

A tomato flavor enhancer, 2-isobutylthiazole (IBT), was added (5 mg/kg) to dressings emulsified with either a whey protein concentrate-80 (WPC-80), a WPC-80 hydrolysate or β-lactoglobulin at high pressure (70 MPa) at either 20 or 75 °C. The short (2-4 min), high-temperature treatment left the proteins essentially unchanged. IBT addition gave a dominant, green tomato flavor that masked the intrinsic odor of the WPC-80 hydrolysate but enhanced bitter flavor. The sensory IBT odor intensity was determined by oil level (5-30%) and pH; pH 4.0 gave higher IBT odor than pH 6.5. The green (IBT) odor release correlated with the sensory viscosity (p = 0.001) and with instrumentally determined complex modulus (p = 0.001), but not to the dressings’ microstructure. The presence of small (<<1.5 µm) oil particles that were difficult to identify from images may explain why no correlation between green odor and microstructure was found. Headspace analysis significantly detected differences in the release of IBT from the different protein types: WPC-80 dressings released the most and β-lactoglobulin the least amounts of IBT into headspace. As this difference in release of IBT among proteins could not be verified by sensory analysis, it may bear no relevance for perception.

Abstract Sheep meat’s flavor and odor may not be as appealing to Indonesians, necessitating genetic improvements in these aspects. The ADH1C (Alcohol Dehydrogenase 1C) gene significantly influences the conversion of ethanol to acetate in liver tissue, directly impacting sheep meat’s flavor and odor. The purpose of this study was to see how ADH1C gene polymorphisms affected sheep meat flavor and odor in Indonesian sheep. The study utilized a sample of 100 rams, including 10 Javanese fat-tailed (JFT), 78 Javanese thin-tailed (JTT), and 12 Jonggol sheep (JS), all aged between 10 and 12 months. To identify polymorphisms and associations of ADH1C|FspI, the researchers employed Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) and General Linear Model (GLM) tests. The results revealed polymorphisms in the ADH1C gene, with two genotypes observed: CG (440, 275, 165 bp) and GG (440 bp). These genotypes were found to be in Hardy-Weinberg Equilibrium (HWE). Moreover, the ADH1C gene displayed a significant (P<0.05) association with 4-methyl octanoic (MOA) and 4-methyl nonanoic (MNA) compounds, with the GG genotype exhibiting the lowest flavor and odor contents. The study suggests that ADH1C with SNP g.25288858 C>G could potentially serve as a marker for selecting Indonesian sheep with a lower flavor and odor.

Thesis (PhD)--Stellenbosch University, 2002.
ENGLISH ABSTRACT: Aged distilled spirits such as whiskey are complex mixtures of flavour compounds in an ethanol-water matrix. The flavour compounds involved can have widely different volatility and relative amounts. Many of the organoleptic properties that make whiskey suitable for commercial sale have their origin in reactions occurring during the ageing process in oak wood barrels. To investigate the complex changes that take place during spirit ageing a preparative fractional vacuum distillation process was developed. Both high and low volatility compounds could be individually isolated as fractions and free from both the ethanol matrix and the fermentation fusel alcohols. This allowed a range of sensory and analytical procedures to be conducted on these fractions, in particular to investigate changes occurring during ageing. Gas chromatographic (GC) analysis of the low volatility fraction is complicated by the fact that both the compounds and their ethanol matrix have very similar chromatographic behaviour when separated simultaneously on standard chromatographic phases. Compound and matrix co-elution becomes a major problem and conditions for mass spectrometric (MS) investigation are disadvantageous. A two-dimensional GC configuration using dissimilar chromatographic phases was configured to overcome these limitations. Using this approach 27 compounds were separated and identified. Headspace injection was used to increase detection sensitivity. Changes with ageing for seven compounds present at very low levels were quantified. In addition changes in the most abundant compounds were quantified by standard split injection, and changes in trace level sulfur compounds by headspace injection with sulfur chemiluminescent detection (SCD). Increases of the concentrations of pleasant fruity ethyl esters and acetates were established. Volatile sulfides with generally objectionable aroma showed concomitant major decreases. Appropriate techniques could also be applied to the low volatility compounds recovered from the whiskey water fraction. High temperature GC-MS analysis of an extract of the water fraction allowed the identification of 30 compounds. Three phenolic esters were identified in whiskey for the first time. These compounds were synthesised and shown to be contributory to desirable ageing flavour. Increases in concentrations of 16 oak derived compounds during alO year ageing period were established. Several compounds increased significantly over this time period. Ratios of aromatic phenolic aldehydes, and changes in these ratios during ageing, were unique to the type of barrel used in these experiments. This suggests that the final sensory properties of aged whiskey may be more dependent on wood parameters than previously thought. Preparative reverse phase High Pressure Liquid Chromatography (HPLC) with an ethanol water gradient was used to further fractionate an extract of the low volatility compounds. Subsequent analysis and sensory testing allowed a group separation of compounds with each group contributing characteristic attributes to the total flavour. One group contained the three new phenolic esters together with a number of other unidentified compounds. This group was found to be important for desirable ageing flavour that seems to develop slowly with time. Further studies in this area to understand the individual and synergistic contributions of the many facets of ageing chemistry will have important commercial implications.
AFRIKAANSE OPSOMMING: Verouderde spiritus soos Whiskey is 'n komplekse mengsel van geurstowwe in 'n etanolwater oplossing. Die vlugtigheid van die geurstowwe asook die konsentrasies waarin hul aanwesig is, varieer aansienlik. Verskeie van die sintuiglike eienskappe wat kommersiële waarde aan whiskey verleen, het huloorsprong in reaksies wat tydens die verouderingsproses in eikehoutvate plaasvind. Ten einde die ingewikkelde veranderinge wat tydens die veroudering van spiritus plaasvind, te ondersoek, is 'n preparatiewe fraksionele vakuumdistillasieproses ontwikkel. Hoogs vlugtige en minder vlugtige verbindings kon geskei word in afsonderlike fraksies wat vry was van etanol en fuselalkohole. Dit het die sintuiglike en fisies-chemiese analises van die fraksies moontlik gemaak, veralom die veranderings wat tydens veroudering plaasvind, te ondersoek. Gaschromatografiese (GC) analise van die fraksie met 'n lae vlugtigheid word gekompliseer deur die feit dat hierdie komponente en die etanol waarin dit opgelos is soortgelyke chromatografiese eienskappe toon wanneer hul gelyktydig op standaard gaschromatografie fases geskei word. Die gelyktydige eluering van dié komponente en etanol waarin hul opgelos is, skep 'n probleem wat nadelig vir massaspektrometriese (MS) analise is. Die beperkings is oorkom deur die gebruik van tweedimensionele GC en stasionêre fases met uiteenlopende eienskappe. Op dié wyse is 27 verbindings geskei en geïdentifiseer. Die veranderinge in konsentrasies tydens veroudering is vir sewe verbindings gekwantifiseer. Veranderinge in die konsentrasies van die verbindings teenwoordig in die hoogste konsentrasies is gekwantifiseer deur split-inspuitings, terwyl veranderinge in die spoorkonsentrasies van vlugtige swawelverbindings mbv dampfase-inspuitings en met swawel chemolumisensie deteksie (SCD) bepaal is. Toenames in die konsentrasies van die aangename vrugtige esters en asetate is bepaal. Vlugtige sulfiede met meesalonaanvaarbare aromas toon gelyktydige groot afnames. Geskikte tegnieke is ook gebruik vir die herwinning van minder vlugtige verbindings met die waterfase van whiskey. Hoë temperatuur GC-MS analises van 'n ekstrak van die waterfase het die identifikasie van 30 komponente moontlik gemaak. Drie fenoliese esters is vir die eerste keer in whiskey gevind. Hierdie verbindings is gesintetiseer en hul bydrae tot die gewenste verouderingsgeur is sintuiglik bevestig. Toenames in die konsentrasies van 16 eikehoutverwante verbindings gedurende 'n verouderingsperiode van 10 jaar is bepaal. 'n Betekenisvolle toename het voorgekom in die konsentrasies van verskeie van hierdie whiskey verbindings. Die verhoudings van aromatiese fenoliese aldehiede en die verandering in die verhoudings tydens veroudering was kenmerkend van die tipe eikehoutvat wat gebruik is. Dié bevinding dui daarop dat die fenole sintuiglike eienskappe van verouderde whiskey meer afhanklik mag wees van eikehout parameters as wat voorheen algemeen aanvaarbaar is. Preparatiewe omgekeerde fase hoëdrukvloeistofchromatografie met etanol/water as 'n gradient elueermiddel is gebruik om 'n ekstrak van die minder vlugtige verbindings verder te fraksioneer. Verdere GC-, MS- en sintuiglike analise het die skeiding van groepe van verbindings waarvan elk kenmerkende bydraes tot die totale geur lewer, moontlik gemaak. Een groep het drie nuut geïdentifiseerde fenoliese esters, tesame met 'n aantal ongeïdentifiseerde verbindings, bevat. Daar is vasgestel dat hierdie groep 'n belangrike bydrae maak tot die gewenste geur wat klaarblyklik stadig tydens veroudering ontwikkel. Verdere ondersoeke in hierdie verband om die individuele en sinergistiese bydraes van verskeie fasette van die chemie van veroudering te verstaan, kan belangrike kommersiële implikasies hê.

Thesis (PhD)--Stellenbosch University, 2004.
ENGLISH ABSTRACT: Yeasts produce a broad range of aroma-active volatile esters and higher alcohols during alcoholic fermentation. Some of these esters and higher alcohols are important for the fruity flavors and therefore the final quality of wine and other fermented beverages. Esters are produced and hydrolyzed by alcohol acetyltransferases and esterases, respectively. In yeast, ester-synthesizing activities are represented by two alcohol acetyltransferases encoded by the ATFI and ATF2 genes, and by an ethanol hexanoyl transferase encoded by the EHTI gene. Atfl p and Atf2p appear responsible for the production of ethyl acetate and isoamyl acetate, while Ehtl p synthesizes ethyl hexanoate from ethanol and hexanoyl-CoA. Although a fair amount of information is available regarding the ATF 1 gene, limited information is available on the remaining alcohol acetyltransferases. Only two genes that code for esterases have been identified in yeast, namely lAHI and TIPI. It has also been shown that the balance between alcohol acetyltransferases and esterases is important for the net rate of ester accumulation. Higher alcohols are synthesized from the a-keto-acids in the branched-chain amino acid metabolic pathway by decarboxylation and reduction. The transamination of the amino acid to the respective a-keto-acid is catalyzed by mitochondrial and cytosolic branched-chain amino acid transferases, which are encoded by the BATI and BAT2 genes, respectively. In recent years, a strong scientific and industrial interest in the metabolism of flavoractive compounds has emerged, but information regarding the roles of specific enzymes and the physiological relevance of their metabolism remains limited. The aim of this project was to investigate the physiological and metabolic consequences of changes in the expression levels of some of the key enzymes involved in aroma compound production. The consequences of these changes on the chemical composition and the fermentation bouquet of wines and distillates were also investigated. The first part of the section on the results in this dissertation reports on the role and relative importance of the Saccharomyces cerevisiae enzymes involved in ester metabolism, namely Atflp, Atf2p, Ehtlp, Iahlp and Tiplp. The corresponding genes were overexpressed in a laboratory strain of S. cerevisiae, BY4742, and in a widely used commercial wine yeast strain, VIN13. Table wine and base wines for distillation were prepared with these VIN13 transformed strains. The ester concentrations and aroma profiles of the wines and distillates were analyzed and compared. The data indicated that the overexpression of ATF 1 and ATF2 increased the concentrations of ethyl acetate, isoamyl acetate, 2-pheylethyl acetate and ethyl caproate, while the overexpression of JAHI resulted in a significant decrease in the concentrations of ethyl acetate, isoamyl acetate, hexyl acetate and 2-phenylethyl acetate. The overexpression of EHTI resulted in a marked increase in the concentrations of ethyl caproate, ethyl caprylate and ethyl caprate, while the overexpression of TJP1 did not decrease the concentrations of any of the esters. In most cases, there was a correlation between the increase in esters and the decrease in higher alcohols. The data suggest that yeast balances the amount of different esters produced through alcohol acetyltransferases and esterases, and that, in some cases, these enzymes appear to overlap in function and/or influence each other's activity. In the second part of the results section, the consequences of the deletion and the overexpression of two genes, BATl and BAT2, which encode transaminases that contribute to the metabolism of higher alcohols, were investigated. The genes were both disrupted in a S. cerevisiae BY4742, and overexpressed in both this laboratory strain and in the VIN13 wine yeast strain. The effects of these modifications on the general physiology of the corresponding yeast strains and on higher alcohol metabolism were assessed in a range of growth conditions, including aerobic and anaerobic growth conditions, in the presence of glucose or raffinose as sole carbon source and growth in the presence of various concentrations of amino acids. Table wine and base wines for distillation were prepared with the modified industrial strains and the concentrations of the higher alcohols and the aroma profiles of the wine and distillates were analyzed and compared. Batl deletion seemed to be lethal under the conditions that were created, and therefore only the bat2!:!.strain, together with the BATI and BAT2 overexpression strains, were investigated. These modifications did not appear to significantly affect the general physiology of the strains. The results obtained indicated that the overexpression of BATI increased the concentrations of isoamyl alcohol and isoamyl acetate, and, to a lesser extent, the concentrations of isobutanol and isobutyric acid. The overexpression of the BAT2 gene resulted in a substantial increase in the levels of isobutanol, isobutyric acid and propionic acid production, and a modest increase in the level of propanol and isovaleric acid. Interestingly, the overexpression of BAT2 led to a decrease in isoamyl alcohol and isoamyl acetate concentrations. Sensory analyses indicated that the wines and distillates produced with the strains in which the BATl and BAT2 genes were overexpressed had more fruity characteristics (peach and apricot aromas) than the wines produced by the wild-type strains. This study offers new prospects for the development of wine yeast starter strains with optimized ester and higher alcohol-producing capability that could assist winemakers in their efforts to consistently produce wine to definable specifications and styles and a predetermined flavor profile.
AFRIKAANSE OPSOMMING: Gedurende fermentasie produseer giste 'n wye verskeidenheid vlugtige aromatiese esters en hoër alkohole. Sommige van hierdie esters en hoër alkohole is belangrik vir die vrugtige geure en dra dus by tot die finale kwaliteit van wyn en ander gefermenteerde drankies. Esters word onderskeidelik deur alkoholasetieltranferases en esterases geproduseer en gehidroliseer. In giste word die ester-sintetiserende aktiwiteite deur twee alkoholasetieltransferases verteenwoordig wat deur die ATFI-en ATF2-gene, asook 'n etanolheksanoïeltransferase wat deur die EHTl-geen, gekodeer word. Dit blyk dat ATFlp en ATF2p verantwoordelik is vir die produksie van etielasetaat en isoamielasetaat, terwyl Ehtl p-etielheksanoaat vanaf etanol en heksanoïel-CoA sintetiseer. Alhoewel daar 'n redelike hoeveelheid inligting t.o.v die ATF I-geen beskikbaar is, is daar weinig inligting oor die res van die aloholasetieltransferases. Slegs twee gene wat vir esterases kodeer, is in gis geïdentifiseer, naamlik IAHI en TIPI. Daar is ook bewys dat 'n balans tussen die alkoholasetieltransferases en esterases baie belangrik is vir die netto-tempo van ester-akkumulasie. Hoër alkohole word gesintetiseer vanaf a-keto sure in die vertakte-ketting aminosuur metaboliese pad deur dekarboksilasie en reduksie. Die transaminasie van die aminosuur na die onderkeidelike a-ketosuur word deur vertakte-ketting aminosuur transferases, geleë in die mitochondrion en sitosol, en gekodeer deur BATl- en BAT2-gene, gekataliseer. In die laaste paar jare het daar 'n sterk wetenskaplike, asook industrïele, belangstelling in die metabolisme van aroma-aktiewe komponente te voorskyn gekom, maar inligting in verband met die rol van spesifieke ensieme en die fisiologiese belangrikheid van hul metabolisme is egter beperk. Die doel van hierdie projek was om die fisiologiese en metaboliese gevolge van veranderinge in die ekspressievlakke van sommige sleutelensieme betrokke by aromakomponent-produksie te ondersoek. Die gevolge van hierdie veranderinge op chemiese vlakke, asook hoe die fermentasie-aroma van die wyne en distillate beïnvloed word, is ook bestudeer. Die eerste gedeelte van die resultate rapporteer oor die rol en relatiewe belangrikheid van die Saccharomyces cerevisiae-ensieme betrokke by estermetabolisme, naamlik Atfl p, Atf2p, Ehtlp, Iahlp en Tiplp. Die gene was ooruitgedruk in 'n laboratoriurnras van S. cerevisiae, BY4742, asook in 'n kommersïele wyngisras, VIN13. Tafelwyne en basiswyne vir distillasie is gemaak met die getransformeerde VIN13-rasse. Die esterkonsentrasies en aromaprofiele van die wyne en distillate is ontleed en vergelyk. Die data het gewys dat die ooruitdrukking van ATFI- en ATF2-gene 'n verhoging in etielasetaat, isoamielasetaat, 2-fenieletielasetaat en etielkaproaat veroorsaak het, terwyl ooruitdrukking van !AHI 'n betekenisvolle afname in etielasetaat-, isoamielasetaat-, heksielasetaat- en 2-fenieletielasetaat-konsentrasies veroorsaak het. Die ooruitdrukking van EHTI het 'n duidelike verhoging in etielkaproaat, etielkaprilaat en etielkapraat veroorsaak en die ooruitdrukking van TIPIhet geen van die esterkonsentrasies verander nie. In die meeste gevalle was daar nie 'n korrelasie tussen die toename in esters en afname in hoër alkohole nie. Die data stelook voor dat die gis 'n balans tussen die verskillende esters handhaaf deur middel van die alkoholasetieltrasferases en esterases, en in sommige gevalle blyk dit dat die ensieme dieselfde funksies het en/of mekaar se aktiwiteit beïnvloed. In die tweede gedeelte van die resultate is die oorsake van delesie en ooruitdrukking van twee gene, BAT1 en BAT2, wat kodeer vir transaminases wat tot hoër alkohol metabolisme bydra, bestudeer. Die gene is uitgeslaan in S. cerevisiae BY4742 en ooruitgedruk in BY4742 en in die wyngisras VIN13. Die effekte van hierdie modifikasies op die algemene fisiologie van die verskillende gisrasse en op hoëralkoholmetabolisme is onder 'n verskeidenheid kondisies bestudeer, naamlik aërobies en anaërobiese groeikondisies, in die teenwoordigheid van glukose of raffinose as die enigste koolstofbron, asook in die teenwoordigheid van 'n verskeidenheid konsentrasies aminosure. Tafelwyne en basiswyne vir distillasie is gemaak met die gemodifiseerde industrïele rasse en die konsentrasies van die hoër alkohole en aromaprofiele van die wyne en distillate is ontleed en vergelyk. Bat1-delesie was dodelik onder die kondisies, daarom is slegs die batlts-tes tesame met die BAT1 en BAT2 wat in die rasse ooruitgedruk is, bestudeer. Die modifikasies het nie 'n beduidende effek op die algemene fisiologie van die rasse getoon nie. Die data het wel getoon dat die ooruitdrukking van BAT1 'n verhoging in isoamielalkohol- en isoamielasetaatkonsentrasies, en tot 'n mindere mate isobutielalkohol- en isobottersuur-konsentrasies, veroorsaak het. Die ooruitdrukking van BAT2 het 'n beduidende toename in isobutanol-, isobottersuur- en propioonsuurkonsentrasies en 'n kleinere toename in propanol- en isovaleriaansuur veroorsaak. Die ooruitdrukking van BAT2 het ook gelei tot 'n afname in isoamielalkohol- en isoamielasetaatkonsentrasies. Sensoriese analises het getoon dat die wyne en distillate wat geproduseer is met die rasse waarin die BAT1 en BAT2 gene ooruitgedruk is meer vrugtige eienskappe (perske- en appelkoos-aromas) getoon het as die wyne wat deur die wildetipe rasse geproduseer is. Die studie lewer nuwe vooruitsigte vir die ontwikkeling van wyngiste met geoptimiseerde ester en hoër alkohol produserende eienskappe wat die wynmakers in staat kan stelom wyne te produseer met gedefinieerde spesifikasies en style en 'n voorafbepaalde aromaprofiel.

Hops (Humulus lupulus L.) are an indispensable component of beer, with the essential oil responsible for imparting distinctive odour and aroma characteristics to beer. However, not all character-impact odorants in hop essential oil have been identified and hop aroma in beer is still not completely understood. The composition of hop essential oil is very complex with 485 compounds currently identified in the literature, and recent research suggests that up to 1000 compounds may actually be present. Only a certain number will be present at concentrations above threshold and make a direct contribution to the odour of the oil. In addition, many important odorants are only present at trace concentrations. Gas chromatography-olfactometry (GC-O) using human assessors is the best way to locate potent odorants and facilitate their identification. A novel methodology was developed to identify the character-impact odorants in hop essential oil samples using hyphenated techniques in gas chromatography. GC-O was used to locate odour active compounds and determine relative importance using CharmAnalysis[TM] according to the odour potency principle. Due to the chemical complexity of the samples, considerable co-elution of peaks occurs during single column gas chromatography (1DGC), making the detection and identification of character-impact odorants challenging. Therefore, comprehensive two-dimensional gas chromatography (GCxGC) combined with time-of-flight mass spectrometry (TOFMS) was used to resolve and identify compounds eluting in the odour active regions. The methodology was developed in a case study on coriander (Coriandrum sativum) and wild coriander (Eryngium foetidum) leaf essential oils. During GC-O analysis of these samples it was recognised that odour active regions frequently coincide with several co-eluting compounds. To address this, a heart-cut multidimensional gas chromatography-olfactometry (MDGC-O) instrument was developed to resolve these 'co-eluting odour clusters' and determine the compound(s) responsible for the odour perception. The 'spicy' character of hops is considered to be a desirable attribute in beer associated with 'noble hop aroma'. However, the compounds responsible have yet to be adequately elucidated. This character was investigated using a commercial 'Spicy' fraction of hop essential oil, selectively enriched for monoterpene and sesquiterpene alcohols. The odour active compounds in (i) the spicy fractions and (ii) the whole essential oils of four different hop varieties were compared using the presented methodology. A compound with an intense 'woody, cedarwood' odour was determined to be a potent, character-impact odorant in all samples. This odour coincided with a complex region of the chromatogram where up to thirteen compounds were co-eluting. The peak responsible for this odour was determined by (i) correlation of peak areas with odour potency (Charm) values and (ii) MDGC-O. The compound was tentatively identified by GCxGC-TOFMS as 14-hydroxy-β-caryophyllene, which has not previously been reported as an odorant in hop essential oil. It was concluded that this compound and other 'woody, cedarwood' odorants contributed to the 'spicy' character of the investigated hop samples. Compounds previously associated with noble hop aroma, notably caryophyllene oxide, humulene epoxides I and II, and humulenol II, did not contribute to the odour character of the hop samples. Other potent odorants that were identified in the whole essential oil and spicy fractions of hops were: geraniol, linalool, β-ionone, eugenol, isovaleric acid, and β-damascenone. While myrcene was a moderately potent odorant in the whole hop essential oil samples, the abundant sesquiterpene hydrocarbons α-humulene, β-caryophyllene and β-farnesene did not significantly contribute to the odour character.

Master of Science
Food Science Institute -- Human Nutrition
Koushik Adhikari
A significant increase in the number of products carried in supermarkets has lead manufacturers to use food color as a way to differentiate their products from competitor’s products or as a form of communication. This report’s overall objective was to review the impact of color on sensory properties of foods and beverages and help product developers understand the multiple sensory properties within a food or beverage that may potentially change by manipulating color. The effect of color on flavor or odor identification, basic taste perception, flavor or odor intensity, quality and refreshment, and consumer acceptance has been extensively researched. Research to date has shown inconsistent findings, although key themes are consistent. Some colors are more appropriate for certain foods and beverages, and product color can be directly linked to palatability. Color cues can be used for flavor identification within a food or beverage, and the presence of certain colors evoke flavor associations within a product. Perceived intensities of basic taste or flavor attributes have increased or decreased merely with color addition. Consumers use color cues to determine quality, therefore color can ultimately affect product acceptance.

Thesis (PhD)--Stellenbosch University, 2005.
ENGLISH ABSTRACT: A number of relevant brewing industry issues associated with malt quality were examined. These included beer foam quality, premature flocculation of yeast during fermentation and antimicrobial factors in malt. The cause of poor foam at a brewery relative to other similar breweries was identified as being related to the boiling temperature during wort preparation and the associated conformational changes of the abundant foam protein lipid transfer protein 1 (LTPl). The temperature range of 96 to 102°C was revealed to be critical. At the higher temperature the denaturation of LTP 1 was more extensive and its effectiveness as a foam protein was reduced. In addition, it was shown that the prominent role of LTPI with respect to foam was as a lipid binding protein, forming a lipid sink and protecting foam from lipid damage. The occurrence of malt associated premature yeast flocculation (PYF) during fermentation was induced in malt by the addition of extra-cellular fungal enzymes to the malt husk or by micro-malting barley in the presence of fungi. In addition, treating malt husk with commercial xylanase or adding commercial arabinoxylan to the fermentation also impacted on yeast flocculation. It was proposed that a range of molecular weight arabinoxylans formed by the enzymatic breakdown of the major barley husk component (arabinoxylan) resulted in PYF. Antimicrobial activity against brewing yeast (Saccharomyces cerevisiae), other fungi and bacteria was found in barley, malt and malt derived wort trub. Wort trub is the non-specific precipitate of protein, polyphenols and lipids formed during wort boiling and which is, to some extend, carried over in the wort to the fermentation. Antimicrobial activity appeared to increase during malting. The growth of brewery collected yeast was inhibited in the presence of brewery production wort when compared to the same wort filtered to remove the trub. Brewery yeast was found to be more sensitive to inhibition than laboratory propagated yeast of the same strain. Different strains of S. cerevisiae were also found to differ in their sensitivity to inhibition. Investigation revealed that the activity originated from the inside of the barley grain and impacted on yeast sugar uptake. However, there was no direct correlation detected between levels of antimicrobial activity in malt and fermentation performance. At high concentrations the factors were microcidal causing cell lysis. Partial characterisation of an antimicrobial extract from malt revealed the presence of a factor between 5 and 14 kDa, containing a cationic peptide component. The optimum pH stability was ±5 when it was also most cationic. The factor easily and irreversibly lost activity at extreme pH and when exposed to certain reagents but was heat resistant in accordance with its survival in wort trub. Preliminary results showed the presence of LTP1 associated with other peptides in the active cationic fraction from the one malt tested. The occurrence of malt related PYF and malt antimicrobial factors are associated with microbial contamination of the grain. The fungi generating the PYF factors from the barley husk while the barley's defence mechanism generates antimicrobial factors to cope with the pathogenic effect of the fungi. In addition there is a potential link between the foam protein LTP 1 and malt antimicrobial activity as LTP 1 or LTP 1 in association with another component(s) is potentially antimicrobial.
AFRIKAANSE OPSOMMING: 'n Aantal problematiese areas in die broubedryf, wat met mout geassosieer word, is ondersoek, naamlik bierskuimkwaliteit, voortydige flokkulering van gis tydens fermentasie en die invloed van antimikrobiese faktore in mout. Die oorsaak van swak bierskuim by 'n spesifieke brouery relatief tot ander soortgelyke brouerye was geidentifiseer as die moutekstrakkookpunt tydens moutekstrakbereiding. Tydens hierdie proses ondergaan dieskuimprotein, lipiedoordrag proteien 1 (lipid transfer protein 1, LTPI), 'n konformasieverandering. Die temperature tussen 96 to 102°C was kritiek t.o.v. ideale konformasieverandering vir skuimaktiwiteit. Denaturering van LTPI het by hoër temperature plaasgevind wat die skuimproteien se aktiwitiet verminder het. Daar is ook bewys dat LTPI 'n verdere rol in bierskuim speel aangesien dit 'n lipiedbindingsproteien is wat die skuimnegatiewe lipiede verwyder. Die voorkoms van moutgeassosieerde voortydige flokkulering van gis (PYF) tydens fermentasie is op twee maniere in mout geinduseer, naamlik: • deur die toevoeging van ekstrasellulêre swamensieme tot die moutdop • deur mikrovermouting van gars in die teenwoordigheid van swamme. Die behandeling van die moutdop met kommersiele xilanase of die toevoeging van kommersiele arabinoxilaan by fermentasies het ook die flokkulering van gis beinvloed. Die hipotese was dat PYF veroorsaak is deur 'n reeks arabinoxilane met verskillende molekulêre massas wat gevorm het tydens die ensimatiese afbraakproses van die primere moutdopkomponent (arabinoxilaan). Antimikrobiese aktiwiteit teenoor brouersgis (Saccharomyces cerevisiae), ander swamme en bakterie was teenwoordig in gars, mout en moutekstrakpresipitaat. Die presipitaat bestaan uit nie-spesifieke presipitate van proteien, polifenole en lipiede wat gedeeltelik in die gekookte moutekstrak agterbly. Daar is gevind dat antimikrobiese aktiwiteit tydens vermouting toe geneem het. Die groeiproses van brouersgis, gekollekteer by 'n brouery, was geinhibeer deur die teenwoordigheid van brouery-geproduseerde moutekstrak in vergelyking met dieselfde moutekstrak wat gefiltreer was om die presipitaat te verwyder. Die brouersgis was meer sensitief heens inhibisie in vergeleke met dieselfde gisstam wat opgegroei is in die laboratorium. Verskillende S. cerevisiae stamme het ook verskille in sensitiwiteit getoon t.o.v. the antimikrobiese komponente in die moutekstrakte. 'n Verdere ondersoek het getoon dat die oorprong van die inhiberende aktiwiteit die interne dele van die gars is, asook dat dit die gissuikeropname beinvloed. Daar was egter geen direkte verband tussen antimikrobiese aktiwiteit in mout en fermentasie effektiwiteit, soos gemeet onder laboratorium toestande, nie. Hoë konsentrasies van die faktore het egter gelei tot seldood weens sellise. 'n Kationiese peptiedbevattende fraksie tussen 5 en 14 kDa en 'n optimale pH stabliliteit van 5 is gevind deur gedeeltelike karakterisering van 'n antimikrobiese moutekstrak. Die aktiewe fraksie se aktiwiteit is onomkeerbaar vernietig by ekstreme pH en blootstelling aan sekere reagense. Die aktiewe verbinding(s) is egter hittebestand en resultate het getoon dat hierdie aktiwiteit die brouproses oorleef as deel van die moutektrakpresipitaat. Voorlopige resultate van die een mout wat getoets is het die teenwoordigheid van LTP 1 getoon, asook die moontlike assosiasie met ander peptiede of kleiner komponente in die aktiewe kationiese fraksie. Die voorkoms van moutgeassosieerde PYF en antimikrobiese faktore in mout word met die mikrobiologiese kontaminasie van gars verbind. Swamme produseer die PYF faktore vanuit die moutdopkomponente, terwyl die plant weer antimikrobiese faktore produseer as deel van 'n beskermingsmeganisme teen die patogene effek van die swamme. Daar is ook 'n potensieele verwantskap tussen bierskuimproteien LTP 1 en antimikrobiese faktore in mout, aangesien LTPI ofLTPl tesame met 'n ander verbinding(s) moontlik antimikrobies is.

This study was conducted to determine the effect of heating methods (conventional and microwave), heating temperatures, and refrigerated storage on the flavor deterioration in precooked chicken parts. Chicken breasts and legs were evaluated by chemical analyses and sensory evaluation. Data was analyzed by Fisher's least significant difference (LSD) and Duncan's test. Results of the thiobarbituric acid test (TBA) indicated that heating temperature, regardless of heating method had a significant influence on oxidative deterioration. When the legs were heated for a longer time at a lower temperature, the TBA values significantly increased indicating heightened warmed-over flavor (WOF). Two-day refrigerated storage had no measurable influence on the TBA numbers. The legs generally had a higher degree of lipid oxidation reflected by higher TBA values. Heating method and 2-day refrigerated storage did not have a significant effect on the nonheme iron content of breasts or legs. The effects of heating temperature were inconsistent for the legs and breasts which was attributed to the different initial iron content of the legs, and the release of nonheme iron during the initial processing of the legs. The nonheme iron values of the legs were greater relative to the breasts. Heating and storage in general increased the area of peak 3 in legs, but had no effect on the breasts. A significant increase in the hexanal (peak 8) content of legs occurred upon 2-day storage, but not for breasts. Peak 7 significantly decreased when the breasts were heated, stored, and reheated. This was not the case for the legs. Sensory panelists could not differentiate between heating methods or temperatures for either part.
Master of Science

The flora of Aotearoa/ New Zealand has evolved in association with birds and lizards as the dominant frugivores and seed dispersers. There is a wide range of ripe fruit colours within the native fleshy-fruited plants spanning the visible light spectrum from red to violet, with the notable exception of green. The evolution of fleshy-fruit and fruiting related trait, may be a result of the selection pressures exerted by different frugivore guilds. This study was conducted to ascertain if endemic diurnal lizards, Oligosoma species (Scincidae: Lacertilia), display features associated with visual based foraging, colour sensitivity and colour preferences, which are necessary conditions to infer a co-evolutionary mutualism between fleshy-fruited plant species and lizards as seed dispersers, which may have influenced the evolution of fruit colour. Many lizards have exceptional colour vision, with the ability to see a wide range of the visual light spectrum from short wave ultra violet to long wave red. They are able to discriminate all aspects of colour: hue, brightness and saturation. Fruit colour within Coprosma (Rubiaceae), is extremely variable, between and within species. The study of fruit colour preferences within this genus and particularly within species with polymorphic fruit colour provides a valuable comparison of frugivore preference to fruit with little inter and intraspecific variation, therefore minimising potentially confounding factors due to phylogeny. Fruit-colour choice experiments were conducted offering fruit from two colour categories based on postulated frugivore preferences; red and red orange fruit has been associated with avian frugivores whilst white and pale fruit has been associated with lizard frugivory in New Zealand. Experiments were conducted both ex-situ, in environmentally controlled laboratories and in-situ at Macraes Flat, Otago. Pilot trials indicated that the background colour on which fruit were presented was important in fruit choice and consequentially, all fruit were offered on a background which provided contrast to both fruit colour categories. The laboratory trials showed some weak evidence for a preference of white and pale blue fruit however, in-situ trials showed a strong preference for white over red fruit. Field studies were conducted to ascertain the composition of fleshy-fruit in the diets of lizards and the results were consistent with those expected for a generalist omnivore; many of the small fruits available to lizards were consumed however, the results indicated that plant abundance does not adequately explain fruit consumption at this field site. A preference index showed that white and pale fruited plants, Melicytus alpinus and Coprosma spp., were preferred over more abundant orange and red fruited plants. Fruit odour was investigated to determine if fruit choice was mediated primarily by visual cues as opposed to odour cues. Fruit choice trials with the fruit concealed from view indicated that fruit choice was based primarily on visual cues in Oligosoma skinks. It is concluded that lizards demonstrate the necessary conditions to infer that as frugivores, they may have influenced the evolution of fruit colour and that within the open habitats of Aotearoa/ New Zealand, the shrubs, particularly the divaricate shrubs may have provided sufficient environmental conditions to establish a mutualism between plants and lizards resulting in the evolution of small, white and other low chroma fruits.

Thesis (MSc)--University of Stellenbosch, 2004.
ENGLISH ABSTRACT: ~-Glucosidases constitute a major group of biologically important enzymes that catalyze the hydrolysis of glycosidic linkages in ~-glucosides, as well as in glycosides that contain only carbohydrate residues, e.g. cellobiose. These enzymes occur in all living kingdoms and perform a variety of functions in organisms ranging from bacteria to highly evolved mammals. Three different types of ~-glucosidases are found in humans, each with its own function: glucocerebrosidase (a deficiency causes Gaucher disease), lactase-phlorizin hydrolase (a deficiency results in lactose intolerance) and cytosolic ~-glucosidase (responsible for the hydrolysis of ~- glucosides ingested with foods of plant and animal origin). In plants, the functions of ~-glucosidases include pigment metabolism, biomass conversion and cyanogenesis, a function it shares with insect ~-glucosidases. Microbial ~-glucosidases, as part of the cellulase enzyme system that is responsible for the hydrolysis of cellobiose and short-chain oligosaccharides into glucose, playa role in the conversion of cellulosic biomass to liquid fuel. These microbial ~-glucosidases also playa very important role in the enhancement of fruit and wine aromas through the liberation of monoterpenols. Monoterpenols play an invaluable role in the flavor and aroma of grapes and wine, and are present as free, volatile and odorous molecules, as well as flavorless, non-volatile glycosidic complexes. These complexes most often occur as 6-0-~-Dxvlopyranosyl- B-Dcqlucopyranosides, 6-0-~-D-glucopyranosyl-~-D-glucopyranosides, 6-0-a-L-arabinofuranosyl-~-D-glucopyranosides, 6-0-a-L-rhamnopyranosyl-~-Dglucopyranosides, or 6-0-~-D-apiofuranosyl-~-D-glucopyranosides of mainly linalool, geraniol, nerol, a-terpineol and hotrienol. Two mechanisms exist for the release of monoterpenes from glycosidically bound non-volatile precursors: acid hydrolysis and enzymatic hydrolysis. As high temperature acid hydrolysis causes a rearrangement of the monoterpene aglycones, the focus has shifted towards the more efficient enzymatic hydrolysis that does not result in modifications of the intrinsic aromatic character of the wine. The endogenous ~-glucosidases of grapes (Vitis vinifera), as well as of the wine yeast Saccharomyces cerevisiae, exhibit very low activity towards the glycoside precursors, and thus the focus has increasingly fallen on the addition of exogenous ~-glucosidases to enhance wine flavor. Fungal, bacterial and some yeast ~- glucosidases have been indicated as effective aroma liberators, but these enzymes are not always suitable for use under the harsh conditions that prevail during winemaking (i.e. low pH, low temperatures, and high ethanol and glucose concentrations). The limited enzyme activities of the abovementioned microorganisms have resulted in a search among non-Saccharomyces yeasts for ~- glucosidases that can withstand these conditions. The ~-glucosidase activities of 20 wine-associated non-Saccharomyces yeasts were quantified, characterized and assessed to determine the efficiency with which they could liberate monoterpenols from their terpenyl-glycosides. The Debaryomyces pseudopolymorphus l3-glucosidase from intracellular crude cell extracts exhibited the most suitable combination of properties in terms of functionality at wine pH, resistance to wine-associated inhibitory compounds (glucose, ethanol and sulfur dioxide), high substrate affinity and large aglycone-substrate recognition. This yeast strain was also used, in conjunction with S. cerevisiae VIN13, for the small-scale fermentation of Chardonnay juice. The results indicated that the l3-glucosidase of D. pseudopolymorphus had definite potential as a wine aroma-enhancing enzyme, as the concentrations of free terpenols (nerol, geraniol and citronellol) were significantly increased during fermentation. Future experimental work would include an in-depth study of the kinetic characteristics of the l3-glucosidases (both cytosolic and cell-associated) exhibiting the highest terpenol-liberating activity under winemaking conditions. The next step would then be the cloning and expression of the most efficient l3-glucosidase gene in a commercial wine yeast. Such a recombinant wine yeast would release grapederived aroma compounds from their non-volatile precursors during single culture fermentations, thereby increasing the sensorial quality of wine.
AFRIKAANSE OPSOMMING: I3-Glukosidases vorm deel van 'n groot groep biologies belangrike ensieme wat die hidrolise van glikosidiese bindings binne l3-glukosiede,sowel as binne glikosiede wat slegs uit koolhidraatresidue bestaan, soos bv. sellobiose, kataliseer. Hierdie ensieme kom in alle koningkryke van lewende organismes voor en verrig 'n wye verskeidenheid funksies binne organismes wat wissel van bakterieë tot hoogs ontwikkelde soogdiere. Drie verskillende tipes l3-glukosidases,elk met sy eie funksie, kom in mense voor: glukoserebrosidase ('n gebrek hieraan lei tot Gaucher-siekte), laktaseflorizinhidrolase ('n gebrek hieraan gee aanleiding tot laktose-intoleransie) en sitosol l3-glukosidase (verantwoordelik vir die hidrolise van l3-glukosiede wat saam met voedsel van plant en dier oorsprong ingeneem word). Die funksies van 13- glukosidase binne plante sluit in pigmentmetabolisme, biomassa-omsetting en sianogenese, wat ook 'n funksie van insek l3-glukosidases is. Mikrobiese 13- glukosidases, as deel van die sellulase-ensiemsisteem wat verantwoordelik vir die hidrolise van sellobiose en kortketting-oligosakkariede na glukose is, speel 'n rol in die omsetting van sellulosebiomassa na brandstof. Hierdie mikrobiese 13- glukosidases speelook 'n baie belangrike rol in die verbetering van vrugte- en wynaroma deur die vrystelling van monoterpenole. Monoterpenole speel 'n belangrike rol in die geur en aroma van druiwe en wyn, en kom voor as vry, vlugtige en aromatiese molekules, asook geurlose, nie-vlugtige glikosidies-gebonde komplekse. Hierdie komplekse is meestal in die vorm van 6-0- I3-D-xilopiranosiel-I3-D-glukopiranosiede, 6-0-a-L-arabinofuranosiel-I3-D-glukopiranosiede, 6-0-I3-D-glukopiranosiel-I3-D-glukopiranosiede, 6-0-a-L-ramnopiranosiel- I3-D-glukopiranosiede,of 6-0-I3-D-apiofuranosiel-I3-D-glukopiranosiedevan hoofsaaklik linalool, geraniol, nerol, a-terpineol en hotrienol. Monoterpenole kan op een van twee maniere van hul suikermolekules vrygestel word: suurhidrolise of ensimatiese hidrolise. Die hoë temperature waarby suurhidrolise plaasvind veroorsaak 'n herrangskikking van die monoterpeen aglikone, en die fokus het gevolglik verskuif na die meer effektiewe ensimatiese hidrolise wat nie verandering van die intrinsieke aromatiese karakter van die wyn tot gevolg het nie. Die endogene l3-glukosidases van druiwe (Vitis vinifera) en die wyngis Saccharomyces cere visiae , toon baie lae aktiwiteit ten opsigte van die aromatiese voorlopers, en dus word daar toenemend op die toevoeging van eksogene 13- glukosidases tot die wyn gefokus om meer geur vry te stel. Daar is bevind dat 13- glukosidases van fungiese, bakteriële en gis oorsprong effektiewe aromavrystelIers is, maar hierdie ensieme is nie altyd gepas vir gebruik in wyn nie, aangesien dit 'n omgewing is met 'n lae pH, lae temperatuur, en hoë etanol- en glukosekonsentrasies. Die beperkte ensiemaktiwitiet van bogenoemde mikroorganismes het gelei tot 'n soeke onder nie-Saccharomyces giste na l3-glukosidases wat in die wynomgewing kan funksioneer. Die ~-glukosidase-aktiwiteit van twintig wyn geassosieerde nie-Saccharomyces giste is gekwantifiseer en gekarakteriseer om te bepaal tot watter mate dit monoterpenole van hul terpeniel glikosiede kan vrystel. Die intrasellulêre ~- glukosidase teenwoordig in the selekstrak van Debaryomyces pseudopolymorphus, het die belowendste resultate getoon ten opsigte van funksionaliteit by wyn se pH, weerstand teen wyn geassosieerde inhibeerders (glukose, etanol en swaweidioksied), hoë substraataffiniteit en breë aglikoon-substraat herkenning. Hierdie gisras is ook in kombinasie met S. cerevisiae VIN13 gebruik vir die kleinskaalse fermentasie van Chardonnay sap. Die resultate het getoon dat die ~- glukosidase van D. pseudopolymorphus wel potensiaal het om wynaroma te verhoog, aangesien die konsentrasie van ongebonde terpenole (nerol, geraniol en citronellol) aansienlik tydens fermentasie toegeneem het. Toekomstige eksperimentele werk sluit in, onder meer, In in-diepte studie van die kinetiese eienskappe van die ~-glukosidases (beide sitesolies en sel-geassosieerd) wat die meeste terpenole onder wynrnaakkondisies vry stel, asook die klonering en uitdrukking van die enkele ~-glukosidasegeen met die hoogste aktiwiteit, in In kommersiële wyngis. Só In rekombinante wyngis sal die vrystelling van druifgebaseerde aromakomponente van hul nie-vlugtige, geurlose voorlopers tydens enkel-kultuur fermentasies teweeg bring.

As the bottled water trend continues to rise across the nation, drinking water utilities have become more concerned with ensuring consumer satisfaction of their product. Although public water supplies are safeguarded by regulations, aesthetically unappealing taste-and-odor problems have led consumers to search for alternative water sources, such as bottled water or tap water processed by point-of-use filters. Consequently, taste-and-odor monitoring has become important to the drinking water industry. Because many utilities use chlorine to disinfect the water, chlorine odor often masks other more subtle odors that may eventually cause consumer complaints. As treated water travels from the water treatment plant to the consumer, chlorine residual diminishes and may reveal a water's naturally less-pleasing odors. Consequently, odor monitoring at the water treatment plant, where chlorine concentrations are at a peak, may not identify potential displeasing smells. Proper evaluation of these odor-causing substances requires that the chlorine odor first be eliminated before evaluating any remaining odors. Dechlorinating agents can remove chlorine, but some will produce other unwanted odors or even remove certain odorous compounds. This research describes the efficiency of several of these agents (ascorbic acid, hydrogen peroxide, oxalic acid, sodium nitrite, and sodium thiosulfate) in dechlorinating chlorinated solutions of the earthy-smelling compound geosmin and musty-smelling MIB. Interfering odors in reusable containers pose another problem in drinking water odor analysis. The most common odor-analysis methods (TON and FPA) involve the use of glass flasks, which often either develop chalky odors or have persistent lingering odors from previous evaluations. Furthermore the glass flasks break easily and are difficult to clean. This research also evaluates the suitability of four types of disposable plastic containers for odor analyses.
Master of Science

The ozone process, which is the latter process of the water purification process, injects ozone to remove taste odor substances from tap water. Still, it is difficult to work the ozone process due to recent changes in water quality, such as taste and odor substances due to climate change. Therefore, this study developed an ozone injection rate determination model and a residual ozone concentration prediction model to properly remove flavor odor substances from raw water and proposed an operational diagnosis and optimal decision-making method for the ozone process in water purification. An ozone injection rate determination model and a residual ozone concentration prediction model were developed using data on water quality, flow rate, and operating conditions measured at Seoul's Y water purification plant. Two models were developed: the random forest and the MLP models. The performance difference between the two was verified by comparing the correlation coefficient and error index. Bayesian optimization, a global search method within a given composition space, was used to determine hyperparameters for each model. RMSE was selected as an objective function to determine the optimal hyperparameter through cross-validation. If the above model is applied to the ozone process, it is expected that an immediate response to changes in raw water quality and human error prevention will be possible.

Sphingoid bases (SPG), a backbone of sphingolipids, are kind of amino alcohol containing long carbon chains. Although the importance of SPG as major component of sphingolipids is well-known, little attention has been paid to the nutritional and chemical properties of SPG itself. Recently, we have found that SPG supplementation to diet-induced obese animals significantly attenuated the abdominal adipose tissue weight gain and the hyperglycemia. Furthermore, we have reported the strong ability of SPG to inhibit the oxidative deterioration of EPA- and DHA-containing oils such as fish oil. Fish oil triacylglycerol (TAG) just after being refined by chromatographic separation has little to no flavor. However, the TAG shows an unpleasant smell less than 1 hr after leaving the chromatograph at room temperature. Although antioxidants and other methods such as microencapsulation in a matrix are used to control the fish oil oxidation, it is still difficult to completely prevent the formation of unpleasant fishy and rancid odors. On the contrary, we have found the effective prevention of the volatile formation in the fish oil TAG oxidation by SPG. The antioxidant activity of SPG synergistically increased in the presence of general antioxidants such as tocopherols. The most likely mechanism for the antioxidant activity of SPG is the formation of novel antioxidants by the amino-carbonyl reaction between the amine group of SPG and the carbonyl group of aldehydes, which are formed in a very early stage of the fish oil oxidation. At the same time, the reaction can result in the removal of aldehydes responsible for flavor deterioration.

High DHA fish oil with ~40% long-chain polyunsaturated fatty acids is beneficial for health. Blending fish oil with milkfat with saturated fatty acids in a chilled environment into solid lipid particles (SLP) increases stability and reduces undesirable taste and odour. SLP can be mixed into dairy products to fortify them with long-chain omega-3 fatty acids. Here, SLPs of fish oil and milkfat with ratio of 50:50 and 70:30 ( w/w) of ~1 mm in diameter were mixed into plain Greek-style yoghurt at 1.2% (w/w). The crystalline structure of SLPs, potential fatty acid leakage, and other physicochemical properties of yoghurt were analysed after 1 day and 28 days of storage at 4°C. Gas chromatographic analysis of yoghurt with and without SLPs showed that the fatty acid composition did not change after 28 days. Sensory evaluation of fresh yoghurt containing SLPs was compared with plain yoghurt, or yoghurt blended with fish oil on an untrained panel of 30 people. This study demonstrated that SLPs could be mixed with yoghurt to maintain stable characteristics for at least 28 days at 4°C. SLPs successfully masked undesirable flavours from fish oil within the yoghurt matrix without any detectable changes in pH, colour, viscosity, and texture.

Just as there are odors that dogs can smell and we cannot, as well as sounds that dogs can hear and we cannot, so too there are wavelengths of light we cannot see and flavors we cannot taste. Why then, given our brains wired the way they are, does the remark, “Perhaps there are thoughts we cannot think,” surprise you? Evolution, so far, may possibly have blocked us from being able to think in some directions; there could be unthinkable thoughts.’ (Hamming, 1980). ‘We have preconceptions about how an intelligent robot should look and act, and these can blind us to what is already happening around us. To demand that artificial intelligence be humanlike is the same flawed logic as demanding that artificial flying be birdlike, with flapping wings. Robots will think different. To see how far artificial intelligence has penetrated our lives, we need to shed the idea that they will be humanlike.’ (Kelly, 2012). In the essay The Doctors of Tomorrow Will Be Supercomputers, published online at futurism.com, Leary (2017) says doctors will be replaced by artificial intelligence-fed supercomputers. This is in line with many theorists and futurists including Kelly (2012) who, on a more "material" level, declared in Wired: Even those areas of medicine not defined by paperwork, such as surgery, are becoming increasingly robotic. The rote tasks of any information-intensive job can be automated. It doesn't matter if you are a doctor, lawyer, architect, reporter, or even programmer: The robot takeover will be epic. And it has already begun.'[Kelly,2013] For this last author, with whom I can only agree, if we are now at a 'point of inflection' in the use of robots, it is because they have become intelligent machines . Indeed, intelligence is the whole question...

• Targeted manipulating Phenylalanine (Phe) synthesis is one of the most powerful strategies to boost the biologically and economically important secondary metabolites, including phenylpropaniods, aromatic volatiles and specialized secondary metabolites. • Over-expression of the petunia MYB transcript factor, ODORANT1 (ODO1), results in significant alterations of the levels of specific phenylpropanoid compounds in plants. • Our previous studies indicated that ectopic expression of the feedback-insensitive AroG could break the bottleneck between primary and secondary metabolisms in tomato, thereby aiding in producing new tomato composition and identifying the unknown roles of multiple key regulators in specialized metabolism. Therefore, combining the AroG and ODO1 is of particular interest for elucidating the combined regulatory role of both of these genes in the Phe metabolic pathway, as well as generating tomato fruits that contain higher levels of secondary metabolites. • Here, we performed the LC-MS and GC-MS analyses on fruits of four tomato genotypes, namely, wild type tomato fruits as well as tomato fruits expressing the AroG, ODO1 and the combination of AroG plus ODO1 (AO) genotypes. Our results elaborated that the levels of many of the Phe-derived metabolites were predominately altered in fruits of the AO genotype, compared to tomato fruits expressing either AroG or ODO1 individually. The levels of most of these metabolites were significantly stimulated, such as Tyrosine (Tyr), coumaric acid and ferulic acid derived metabolites, but the levels of some important secondary metabolites were reduced in the AO transgenic genotypes as compared to either AroG or ODO1 lines. Nevertheless, our results also revealed that the levels of aromatic volatiles were obviously down regulated in the AO, compared to that in AroG transgenic fruits, but were boosted while compared to the wild type and ODO1 transgenic fruits. • Our results suggest that ODO1 expression may also have a negative effect on the production of some of the aromatic volatiles in tomato fruits, indicating that ODO1 acts as an important regulator of the shikimate pathway, which leads to the production of the aromatic amino acids and secondary metabolites derived from them. Key words: AroG, ODO1, tomato, metabolism, shikimate pathway

The objectives of this project were to develop procedures and models, based on neural networks, for quality sorting of agricultural produce. Two research teams, one in Purdue University and the other in Israel, coordinated their research efforts on different aspects of each objective utilizing both melons and tomatoes as case studies. At Purdue: An expert system was developed to measure variances in human grading. Data were acquired from eight sensors: vision, two firmness sensors (destructive and nondestructive), chlorophyll from fluorescence, color sensor, electronic sniffer for odor detection, refractometer and a scale (mass). Data were analyzed and provided input for five classification models. Chlorophyll from fluorescence was found to give the best estimation for ripeness stage while the combination of machine vision and firmness from impact performed best for quality sorting. A new algorithm was developed to estimate and minimize training size for supervised classification. A new criteria was established to choose a training set such that a recurrent auto-associative memory neural network is stabilized. Moreover, this method provides for rapid and accurate updating of the classifier over growing seasons, production environments and cultivars. Different classification approaches (parametric and non-parametric) for grading were examined. Statistical methods were found to be as accurate as neural networks in grading. Classification models by voting did not enhance the classification significantly. A hybrid model that incorporated heuristic rules and either a numerical classifier or neural network was found to be superior in classification accuracy with half the required processing of solely the numerical classifier or neural network. In Israel: A multi-sensing approach utilizing non-destructive sensors was developed. Shape, color, stem identification, surface defects and bruises were measured using a color image processing system. Flavor parameters (sugar, acidity, volatiles) and ripeness were measured using a near-infrared system and an electronic sniffer. Mechanical properties were measured using three sensors: drop impact, resonance frequency and cyclic deformation. Classification algorithms for quality sorting of fruit based on multi-sensory data were developed and implemented. The algorithms included a dynamic artificial neural network, a back propagation neural network and multiple linear regression. Results indicated that classification based on multiple sensors may be applied in real-time sorting and can improve overall classification. Advanced image processing algorithms were developed for shape determination, bruise and stem identification and general color and color homogeneity. An unsupervised method was developed to extract necessary vision features. The primary advantage of the algorithms developed is their ability to learn to determine the visual quality of almost any fruit or vegetable with no need for specific modification and no a-priori knowledge. Moreover, since there is no assumption as to the type of blemish to be characterized, the algorithm is capable of distinguishing between stems and bruises. This enables sorting of fruit without knowing the fruits' orientation. A new algorithm for on-line clustering of data was developed. The algorithm's adaptability is designed to overcome some of the difficulties encountered when incrementally clustering sparse data and preserves information even with memory constraints. Large quantities of data (many images) of high dimensionality (due to multiple sensors) and new information arriving incrementally (a function of the temporal dynamics of any natural process) can now be processed. Furhermore, since the learning is done on-line, it can be implemented in real-time. The methodology developed was tested to determine external quality of tomatoes based on visual information. An improved model for color sorting which is stable and does not require recalibration for each season was developed for color determination. Excellent classification results were obtained for both color and firmness classification. Results indicted that maturity classification can be obtained using a drop-impact and a vision sensor in order to predict the storability and marketing of harvested fruits. In conclusion: We have been able to define quantitatively the critical parameters in the quality sorting and grading of both fresh market cantaloupes and tomatoes. We have been able to accomplish this using nondestructive measurements and in a manner consistent with expert human grading and in accordance with market acceptance. This research constructed and used large databases of both commodities, for comparative evaluation and optimization of expert system, statistical and/or neural network models. The models developed in this research were successfully tested, and should be applicable to a wide range of other fruits and vegetables. These findings are valuable for the development of on-line grading and sorting of agricultural produce through the incorporation of multiple measurement inputs that rapidly define quality in an automated manner, and in a manner consistent with the human graders and inspectors.