Dissertations / Theses on the topic 'Matière grasse du lait – Oxydation'
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Radanielina-Para, Marie Philippe. "Étude de la stabilité oxydative de l'acide linoléique conjugué dans la matière grasse latière." Master's thesis, Université Laval, 2007. http://hdl.handle.net/20.500.11794/20224.
Najib, Mustapha. "Étude du procédé de fabrication et caractérisation des interactions moléculaires lors de la fabrication de la Qishta et évaluation de la stabilité du produit alimentaire." Electronic Thesis or Diss., Université de Lille (2018-2021), 2020. http://www.theses.fr/2020LILUR057.
Qishta is a Lebanese dairy product obtained by heating whole milk for 2 to 3 hours in an open shallow vessel. During the process, milk is added to readjust its level and compensate the amount of evaporated water. The process consists of harvesting the coagulum formed at the milk surface. Our findings showed that these aggregates result from the denaturation of milk proteins and their interactions with the fat globules. This work has demonstrated that Qishta has almost the same amount of proteins and fat estimated at 12% and therefore the product has a composition similar to that of Ricotta cheese made from whole milk. The characterisation of Qishta using mass spectrometry has allowed to determine and quantify the proteins present in Qishta. These analyses have demonstrated also the presence of “Cross links” between proteins which are involved in the Qishta coagulum formation. Lanthionine and lysinoalanine were identified as neoformed amino acids during the heat treatment. These amino acids are involved in the cross links formed during the heat treatment of milk. These amino acids will establish covalent bonds between the proteins of Qishta coagulum. The confocal laser scanning microscopy analyses of Qishta samples previously treated with Fast Green and Nile red dyes have allowed to highlight the protein-fat interactions considered as the source of coagulum formation.Our findings showed the significant effect of the fat amount present in the initial milk on the process and the yield of Qishta. Increasing the amount of milk fat leads to an increase in the Qishta yield. A milk with 3.2% of fat has given the maximum yield. However, the use of skim milk in the production did not nor lead to any coagulum formation.The effect of ageing during Qishta storage for 20 days at 4 ℃ on the fat oxidation and therefore on the Qishta shelf life has been realized. The results of the primary and secondary indicators of oxidation analyses have showed the fat present in Qishta was not oxidized during the study period.In addition, the emission spectra of tryptophan, riboflavin and the excitation spectra of vitamin A were directly recorded using frontal fluorescence on Qishta stored at 4 ° C for 20 days.The analysis of these spectra by multidimensional statistical tools such as principal component analysis and discriminant factor analysis has allowed to significantly differentiate Qishta samples. Indeed, these analyses have allowed to significantly distinguish between the samples and subsequently predict their shelf life of the product
Fauteux, Marie-Christine. "Évaluation de l'effet d'apports de caroténoïdes de la luzerne déshydratée sur son transfert dans les sécrétions lactées et la stabilité oxydative des matières grasses du lait." Thesis, Université Laval, 2014. http://www.theses.ulaval.ca/2014/30618/30618.pdf.
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Ozenne, Catherine. "Biofaçonnement de la matière grasse du lait." Montpellier 2, 1993. http://www.theses.fr/1993MON20159.
Couvreur, Sébastien. "La Variabilité individuelle des vaches laitières et l’alimentation permettent de moduler les fonctionnalités des globules gras." Rennes, Agrocampus, 2006. http://www.theses.fr/2006NSARB174.
Diagana, Yacouba. "Optimisation et faisabilité industrielle d'un procédé de fractionnement de la MGLA par microfiltration hydrophobe." Vandoeuvre-les-Nancy, INPL, 1997. http://www.theses.fr/1997INPL056N.
The study of new fractionation process of anhydrous milk fat (AMF) was carried out on two types of module : plane and axial. After a detailed study on the plane configuration, equiped by specific membranes, we noted that the behaviour of solid fat content of retentate compared to AMF initial was not satisfactory. This configuration presented the inconvenience of membrane fragility and cleaning difficulties. Thus the plane configuration was abandoned and an axial configuration, equiped with two types of membranes (hydrophilic and hydrophobic), was used. Fractionation on hydrophilic membrane showed TG partition cut-off at CN 40 between permeate and retentate. Thus, a permeate rich in low molecular weight TG (CN < 40) and a retentate rich in a high molecular weight TG (CN > 40) was obtained. Meanwhile, using hydrophobic membrane in fractionation gave permeate rich in low molecular weight TG, but also rich in polyinsaturated high molecular weight TG. 50, The physical properties, particularly the solid fat content, of permeate and retentate was modified considerably compared to initial AMF. Membrane fractionation of AMF is not an exclusif phenomenon because all TG present in the melted AMF could pass through these membranes. 50, membrane separation of TG was based on the physical and chemical affinity between the TG molecules and the membranes. This affinity was strongly affected by the hydrodynamics conditions of filtration
Leduc, Maxime. "Production de matière grasse laitière bovine enrichie en acide a-linolénique." Doctoral thesis, Université Laval, 2018. http://hdl.handle.net/20.500.11794/28244.
The alpha-linolenic acid (c9c12c15 18:3; ALA) has potential health benefits when consumed by humans and a strong marketing potential for enriched products. However, the concentration of ALA in dairy cow milk is low, less than 1.00 g/100 g of fatty acid (FA) due to a biochemical process called biohydrogenation (BH), which makes the production of milk enriched in ALA difficult. Biohydrogenation is done by ruminal bacteria and consists of the hydrogenation of the double bonds present in ALA. This mechanism leads to a low concentration of ALA and a high concentration of saturated FA and trans FA in ruminant milk and meat. The objective of this thesis is to evaluate different strategies for reducing BH of ALA in dairy cows in order to increase naturally ALA concentration in milk. Four different approches were evaluated in this thesis: 1) feeding red clover (RC), which is a source of polyphenol oxidase (PPO); 2) feeding different concentrations of rumen degradable protein; 3) feeding calcium (Ca) salts rich in ALA with two different particle sizes; and 4) using a meta-analysis on flaxseed. The first experiment tested the effect of feeding RC (source of PPO) compared to alfalfa (AL) and the effect of 100 or 85 % of recommendation in the supply of rumen degradable protein (RDP-100; RDP-85). Eight fistulated cows (72 ± 17 days in milk; DIM) were used in a double Latin 4 × 4 square design 4 × 4 (21 d period/14 d of adaptation) with the following factorial treatments: RC+RDP-100, RC+RDP-85, AL+RDP-100 and AL+RDP-85. Red clover increased ALA concentration in milk (0.69 vs 0.43 g/100g of fat; P < 0.01). Transfer efficiency of ALA from diet to milk was higher for RC (10.9 %) compared to AL (5.9 %; P < 0.01). No difference was observed between RDP-100 and RDP-85 for ALA milk concentration and transfer efficiency from diet to milk. For the second experiment, eight Holstein cows (115 ± 14 DIM) were used in a double Latin square (4 × 4) with treatments consisting of giving 600 g/day of a mix of FA providing 231 g ALA/day in the following forms: 1) coarse calcium salts (CCS); 2) fine Ca salts (FCS); 3) triacylglycerols (Negative control; N-CTRL) in the rumen; 4) triacylglycerols (Positive control; P-CTRL) in the abomasum. Orthogonal contrasts were used to compare each treatment to CCS. The concentration of ALA was superior for CCS (2.52 g/100 g of fat) when compared to N-CTRL (0.59 g/100 g of fat; P < 0.01) and FCS (1.31 g/100 g of fat; P=0.06, tendency) and was inferior when compared to P-CTRL (8.06 g/100 g of fat; P < 0.01). Transfer efficiency of ALA from diet to milk for CCS (8.4%) was superior to FCS (4.2%; P=0.03) and N-CTRL (1.7%; P < 0.01) and inferior to P-CTRL (26.4%; P < 0.01). Finally, a meta-analysis was used to evaluate the feeding value of different forms of flaxseed (oil, seed, or fractions of seed) on milk production, milk components, milk FA, and transfer efficiency of ALA from diet to milk in cows. The database consisted of 78 articles with a minimum of one treatment containing flaxseed. Higher concentrations of ALA were observed with protected flaxseed (1.67 g/100 g of fat) and flax hulls (1.62 mg/g of fat). The highest transfer efficiency of ALA from diet to milk was observed with mechanically processed whole seeds (rolled or ground), chemically protected flax seed and flax hulls with 5.84, 6.50, and 4.79 %, respectively compared to oil and whole seed intact and extruded. In conclusion, it was impossible, with our strategies, to achieve a concentration of ALA that meets Health Canada rules, i.e. a contribution of 300 mg of ALA per portion or concentration of 4.1 g/100 g of fat in a glass of whole milk (250 mL) at 3.25% of fat.
Jurjanz, Stefan. "Modulation de la qualité du lait par l'amidon de la ration." Vandoeuvre-les-Nancy, INPL, 2001. http://docnum.univ-lorraine.fr/public/INPL_T_2001_JURJANZ_S.pdf.
The effect of variations in the source and amount of starch provided by the diet on the milk production of cows was studied du ring 5 trials with different starch levels and sources. These variations were realized using wheat or potatoes in total mixed diets based on grass silage or maize silage. Ln sacco kinetics confirm that wheat starch disappears more quickly than potato starch in the rumen (instantaneous solubility of 65% and 40% respectively). The daily starch intake with maize silage based diets is over 6 kg per cow. Ln view of the rapid degradation of maize silage starch in the rumen (86% of instantaneous solubility), these diets can be characterized by a rapid (wheat - maize silage) or mixed speed of starch degradation (potatoes - maize silage). The milk and protein yields increase with the starch supply even if the protein and fat contents decrease for supplies over 6-7 kg per day. This threshold separates the diets based on grass silage or maize silage. The dry matter intake, milk and protein yields do not vary between the diets containing one of the starch concentrates. So, the main result of this work is the decreased milk fat (content and yield) with wheat in comparison to potatoes in maize silage based diets (respectively - 2,6 to -3,3 g fat/kg milk and -71 to -122 g fat/day) i. E. In diets with a starch supply of over 7kg per day. The milk fat composition shows significantly fewer short and medium chain fatty acids and more long chain fatty acids (+3,6%) with wheat diets compared to potato diets. No differences in ruminai fermentation were shown between the two starch concentrates in these rations. The postprandial pH drop is stronger with wheat diets but no differences were observed for VFA concentration or composition or blood metabolites. As the milk fat precursors did not vary between the two diets, the lower milk fat content with wheat could be due to an inhibition of the activity of essential enzymes for milk fat synthesis. Lndeed the milk fat of cows eating the wheat diet is significantly richer in C 18:1 trans (4,4 versus 2,7%) especially for the ∆10 isomer (+ 1 ,46%) - a fatty acid known as being an efficient inhibitor of key-enzymes of de nova synthesis and desaturation
Alfonso, Avila Angel Rene. "Influence du profil minéral de la ration sur la production de matière grasse du lait." Doctoral thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/34514.
Negative energy balance typically appears in early-lactation dairy cows as a consequence of a reduction of dry matter intake, as well as of an increase in energy demand for milk production. To compensate this energy deficit, cows are fed with high-concentrate diets. However, highly fermentable carbohydrates introduced in diets can result in a decreased milk fat synthesis. Previous studies reported that addition of potassium carbonate (K2CO3) to high-concentrate diets helps to maintain milk fat, although the mechanism is yet to be established. Consequently, the objective of the current thesis was, firstly, to investigate the effects of dietary cation-anion difference (DCAD), cation source, and buffering ability of the mineral supplement on rumen biohydrogenation of fatty acids (FA) and production performance of dairy cows fed a high-concentrate diet. Secondly, this thesis aimed at evaluating the effect of K2CO3 on production performance, biohydrogenation of fatty acids, and mineral composition of milk in early-lactation dairy cows fed a high-concentrate diet with or without soybean oil (SBO), as a source of polyunsaturated fatty acid. A third objective of this thesis was to evaluate the effect of K2CO3 supplementation, in diets containing soybean oil (SBO) on rumen microbial population associated with lipid metabolism. Consequently, a first experiment was set up, where 35 early-lactation Holstein cows were used in a randomized complete block design with 33-d periods, including a 5-d pretreatment collection period used as a covariate. Five different dietary treatments were used to assess the effects of K2CO3 (control vs. K2CO3), buffering ability (K2CO3 vs. KHCO3), DCAD (K2CO3 vs. KCl), and cation type (K2CO3 vs. Na2CO3). In this experiment, and as opposed to previous studies, supplementing high-concentrate diets with K2CO3 did not increase milk or milk fat yield in early-lactation cows. Also, results suggested that increasing dietary K through the addition of K2CO3 could lead to a disequilibrium in cellular ion composition that can impair nutrient transport into and out of the mammary epithelial cells, and consequently affect milk synthesis. A second experiment was conducted where 28 ruminally fistulated Holstein cows were used in a randomized complete block design. The experiment lasted 33 d, including a 5-d pre-treatment collection period used as a covariate. Experimental treatments were arranged as a 2 × 2 factorial with 0 or 1.5% K2CO3 and with 0 or 2% SBO. Results of this experiment revealed that potential effect of K2CO3 on milk fat synthesis is dependent on the levels of dietary polyunsaturated FA. Moreover, a positive relation was established between milk Cl concentration and milk yield, suggesting that the equilibrium of this ion is linked to the efficiency of lactogenesis Finally, rumen samples were collected from the rumen of 24 cows enrolled in the second experiment (n = 6) to assess treatment effects on rumen microbial population associated with lipid metabolism. Feeding K2CO3 and SBO had distinct effects on rumen bacteria. Dietary K2CO3 stimulated the growth of Butyrivibrio hungatei, a bacterium recognized to produce trans-11-18:1 during biohydrogenation. Conversely, feeding SBO reduced the growth of Butyrivibrio/Pseudobutyrivibrio bacterium group, known to produce trans-11-18:1, of Fibrobacter succinogenes, a fibrolytic bacterium, of Butyrivibrio proteoclasticus, a bacterium involved in 18:0 production, and of Streptococcus bovis, an amylolytic bacterium. Overall, the experiments conducted and reported in this thesis provide new insights on the impact of mineral supplementation on milk performance in dairy cows.
Bugeat, Simon. "Triacylglycérols de la matière grasse laitière enrichie en acides gras insaturés : structures cristallines et fonctionnalités." Rennes, Agrocampus Ouest, 2011. http://www.theses.fr/2011NSARB215.
Including about 65% of saturated fatty acids (SFA) considered harmful to human, milk fat (MF) is present in a lot of food products. Triacylglycerols which are esters of glycerol and fatty acids are the major components of MF. The composition and structural complexity of MF provides specific crystallization properties and organoleptic qualities highly valued in several products: butter, creams, foams, etc. The stake is thus to decrease the SFA rate of MF while keeping its cooking properties. The objective of this PhD thesis is to quantify the physical properties of SFA-lowered MF obtained thanks to animal feeding strategy into forms of increasing complexity: anhydrous MF, emulsified MF (milk and model emulsion) and MF in end products (butter and cheese). Therefore, a systemic approach was used; the samples were studied for their composition and physical properties at different scales: molecular, microscopic and macroscopic. Hence, the crystals formed by these modified triacylglycerols show molecular characteristics directly linked to the nature of their fatty acids. The thermal stability of these crystals is altered: although keeping a global temperature of fusion range, they hardly reorganize in the 0-20°C zone. The hardness properties of these triacylglycerols is lowered by 30%. In emulsion, the droplet size strongly impacts the nucleation mechanism and the crystals nature of such complex triacylglycerol mixes
Maxin, Gaëlle. "Développement d’un modèle de prédiction de la matière grasse du lait basé sur les flux de nutriments chez la vache laitière." Rennes, Agrocampus Ouest, 2011. http://www.theses.fr/2011NSARB210.
Fluctuations in the milk fat market are driving demands from farmers for ways to control milk fat production and composition in dairy cows. Dietary changes are a simple way to modulate milk fat content (MFC) and milk fat yield (MFY) since these effects are rapid and reversible. The current models used to estimate dairy cow requirements and formulate diets cannot predict changes in milk fat. These models are based on energy and protein intake and do not consider the pattern of individual nutrients derived from digestion. A better knowledge of the effects of the nutrients and their individual contributions to the observed responses of milk fat could enable to develop a model to predict milk fat responses to dietary changes. The objective of this thesis was to design and evaluate an empirical model to predict milk fat responses to dietary changes using nutrient flows. The work was carried out in 3 steps: 1/ quantification of the effects of nutrients on MFC and MFY; 2/ test of the additivity of nutrients on milk fat production and composition; 3/ design and evaluation of the predictive model. The response equations of MFC and MFY to the supply of 7 nutrients identified to act on milk fat secretion were established by meta-analyse using studies involving digestive infusions of these nutrients. Then, potential interactions between these nutrients on milk fat secretion were tested during two experimental studies: 3 nutrients that have similar or opposite effects on milk fat secretion were infused alone or simultaneously to dairy cows. The effects of tested nutrients were additive on milk fat production and composition in both studies. Finally, the predictive model was built by coupling published empirical equations which estimated the nutrients flows from diets with the milk fat response equations to these nutrients (i. E. Equations established previously). The overall response of MFC and MFY were calculated by addition of the responses to all nutrients. The model was evaluated by comparing the predicted and observed responses of MFC and MFY on several databases composed of published feeding studies in dairy cows. The quality of prediction of the model varied with the dietary changes used to evaluate the model and several ways of model improvement were identified. In conclusion, by combining experimentation and modelisation, this thesis enabled to develop a model predicting MFC and MFY responses to dietary changes and to bring knowledge on the nutritional regulation of milk fat secretion
Goibier, Lucie. "Techniques de structuration et d'émulsification de la matière grasse laitière." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0221.
Yoghurts and ice creams are food materials obtained from dairy emulsions. This study is concerned with the development of strategies for fat reduction in ice creams and yoghurts without altering physico-chemical and organoleptic properties. For that purpose, we first worked on a model dairy emulsion based on anhydrous milk fat dispersed in an aqueous solution containing sodium caseinate. The first approach is based on the increase of the fat droplets’ size induced by an instability occurring in oil-in-water emulsions composed of crystallizable triglycerides: partial coalescence. To induce partial coalescence, low molecular weight surfactants must be added to displace proteins from the interface. We performed a screening of various surfactants according to their ability to induce partial coalescence in a dairy emulsion. We showed that liquid surfactants induced partial coalescence, whereas this phenomenon was prevented when crystallizable surfactants, composed of long saturated fatty acid chains, were added. In this latter case, we provided evidence for the formation of a rigid barrier protecting fat droplets against partial coalescence. The second strategy was based on the incorporation of a fat free fraction in fat droplets. Two systems were developed: Water-in-Oil-in-Water (W/O/W) and Air-in-Oil-in-Water (A/O/W) double emulsions. Both systems were formulated without lipophilic surfactant, the fat free fraction being stabilized solely by endogenous fat crystals. The characteristics of these systems, as the fat droplets’ size and the encapsulation yield were finely tuned by varying the shear rate. We generalized the concept to other crystallizable oils such as palm, coconut oil or cocoa butter. We also evidenced original properties of these double emulsions, especially their resistance to an osmotic stress (W/OW emulsions) and their thermo-responsiveness. Both strategies were finally transposed to the pilot scale
Schreyer, Arnaud. "Régulation électrochimique du potentiel d'oxydoréduction du lait : impact des composantes du lait et effet sur sa résistance à l'oxydation après traitement." Thesis, Université Laval, 2007. http://www.theses.ulaval.ca/2007/24539/24539.pdf.
B, Vigneux Marie-Pier. "Impact de l'homogénéisation partielle de la matière grasse du lait et de l'homogénéisation haute pression (HHP) du lait écrémé sur ses aptitudes à la transformation fromagère." Master's thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/27845.
Homogenization is a mechanical treatment which by its effects of cavitation, turbulence and shear, modifies the properties of milk fat globules (MFG) and if applied at high pressures, decreases the size of casein micelles. This project aimed to determine the effects of the homogenization of a portion of the fat and of the high-pressure homogenization of the skim fraction on the cheesemaking properties of milk. The milk fat was homogenized before being used in cheese making. The homogenization caused a reduction in the size of the MFG and an increase in the protein load. However, these effects were less pronounced when the fat content was higher at the time of homogenization. The cheese milks were standardized with proportions of homogenized fat varying from 0 to 100%. The storage modulus of the curd, 60 minutes after renneting, increased with the proportion of homogenized fat. In addition, cheese moisture and lipid retention also increased with the proportion of homogenized fat. This study proposes new technological approaches that can improve yields and control the composition of cheeses. Raw skim milk was homogenized at four different pressures (0, 50, 100, 150 MPa) with one or three passes in the homogenization valve. The homogenized milks were characterized and the cheese properties were measured. The size and zeta potential of the casein micelles decreased with decreasing the homogenization pressure. Despite these effects on the structural properties of the casein micelles, the homogenization of the skim milk did not alter its cheese processing properties. This conclusion, however, applies to homogenization pressures of less than 150 MPa and it would be pertinent to evaluate the impact of more severe treatments.
Mannai, Hanen. "Impact du profil en acides gras de la ration des vaches laitières sur la teneur en matière grasse du lait en conditions commerciales." Master's thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/25677.
Poisson, Laurent. "Valorisation enzymatique de lipides : synthèse de cires à partir de la matière grasse laitière : production et traitements d'acides gras polyinsaturés de microalgues." Le Mans, 1999. http://www.theses.fr/1999LEMAA002.
Kamleh, Rabih. "Composition physico-chimique des différents laits de la plaine de la Bekaa : composition et caractéristiques rhéologiques des différents beurres produits." Vandoeuvre-les-Nancy, INPL, 2005. http://www.theses.fr/2005INPL026N.
Cows' milk characteristics, milk fat and the rheological properties of different produced butters in four different regions in the Bekaa valley in Lebanon have been studied. Major milk components, milk fats and butter characteristics have shown significant seasonal and regional variations. The major milk components were high during the cold period due to the minimal milk production and the feed composition. Two different peaks of the somatic cell count have been noticed: the first during the fall season related to the hygiene situation of the farms and the second during the spring season related to the high calving rate. The short chain fatty acids were high during the cold period due to the stage of lactation. The long chain fatty acids variations were related to the feed composition. The solid fat content (SFC) and the fusion's enthalpy (J/g) of high melting triacylglycerols were high during the cold period in ail the districts with an exception in Central Bekaa where the impact of the feeding composition was clear. The butters' humidity was high during the hot season. Significant fluctuations of the rheological properties have been identified in fall season probably related to the triacylglycerols compositions' variations. Significant correlations were established between the rheological characteristics of butters (hardness, cohesiveness and suppleness) the composition and the characteristics of milk fat (short and long fatty acids and fusion's enthalpy oftriacylglycerols)
Duponchel, Ludovic. "Validation par les méthodes chimiométriques d'un analyseur spectrométrique de lait travaillant dans le proche infrarouge : transfert de calibration en vue de développements industriels." Lille 1, 1997. http://www.theses.fr/1997LIL10155.
Deligny, Cécile. "Étude expérimentale de la pâte feuilletée levée : comportement au laminage et à l'expansion." Thesis, Rennes 1, 2013. http://www.theses.fr/2013REN1S183/document.
Laminated dough is characterized after baking by a unique light and flaky texture which is the result of alternating thin sheeted layers of dough and fat. The aim of the present study was to visualize the layers and quantify their feature in Danish pastry like laminated dough. The effect of the number of layers was studied in order to have different structures of the layers. Two imaging techniques offering different spatial resolutions (1.24µm and 0.5mm/pixel) were combined: CLSM to characterize the fat layers after sheeting and MRI to study dynamically the layers during proving. The developed method from CLSM images allowed quantification of layers thickness and of the elastic recoil of dough layers. Two scales of fat breaches after sheeting were measured by complementary of the two imaging methods. A new method of quantification of the three components (gas, paste and fat) on each pixel in MRI images with partial volume during proving, was used. It made possible to monitor expansion of individual dough layers. Neither the number of fat layers (4, 8 and 12), nor the height position of dough layer, had an effect on the expansion rate. The proving step contributed to most of the expansion of Danish pastry, but with no specific role of fat layers. During baking, relative expansion of Danish pastry ranged from 20 to 65% for 4 to 32 fat layers and remained unchanged above 48 layers
Berton, Amélie. "Propriétés structurales et fonctionnelles des lipases pancréatiques apparentées de type 1 et 2 : rôle dans la digestibilité de la matière grasse laitière." Aix-Marseille 1, 2009. http://www.theses.fr/2009AIX11050.
The pancreatic lipase/colipase system plays a key role in triglycerides duodenal digestion. In 1992, two proteins with a high sequence and structure homology with pancreatic lipase (PL) were discovered in the pancreas of several species. These enzymes, named pancreatic lipase related proteins 1 and 2 (PLRP1 and PLRP2), display very different functional properties in comparison to PL. Their physiological role is still unknown. We first investigated the respective role of the structural domains of the horse PLRP2 in its functional properties through the characterisation of chimera proteins PL/PLRP2. The inability of horse PLRP2 to bind to colipase is due to its C-terminal domain and the Nterminal domain is involved in the substrate specificity, the specific activity and the activation of this enzyme. The studies related to the retinyl palmitate hydrolysis by the pancreatic lipases suggest that PLRP2 preferably hydrolyses substrates when it is incorporated in micelles. Human PLRP2 expressed in the Pichia pastoris yeast, not sensitive to colipase, has a particular proteolytic cleavage site as horse PLRP2. A second part of our work, concerning the studies of the digestibility of a complex natural substrate, the dairy fat, brings new insights concerning the respective contribution of the human pancreatic lipases in the lipids digestion. The cow milk allows to obtain native or dairy processed (homogenisation) milk fat globules with different size and structural organisation. If PLRP1 displays no lipolytic activity on milk fat globules, the efficiency of PLRP2 to hydrolyse the dairy fat is lower than those of PL and its activity is sensitive to colipase. The catalytic efficiency of PLRP2 is higher on homogenized than on native milk fat globules and the PL activity is influenced by the size of native milk fat globules. Finally, the PLRP1 has an inhibitory effect on the PL activity and, a synergic action is highlighted between PL and PLRP2. Our study confirms that the dairy fat structural organisation influences its digestibility. It supports the hypothesis of a PLRP2 role in newborns and raises the question whether pancreatic lipase related proteins have to be considered as modulators of the PL activity rather than lipases per se
Aguiar, Prado Lucas De Ofeu. "Prédiction de la production et de la composition de la matière grasse du lait par modélisation : rôle des flux de nutriments absorbés." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLA015/document.
Milk fatty acids (FA) composition in dairy cows results from lipid metabolism in rumen and mammary gland. In the context of renewing the INRA feed unit system, the objective of this work is to predict, by a quantitative approach using metaanalysis, duodenal flows of FA in ruminants, FA transfer from the intestine to the mammary gland, and the secreted FA flows in the milk. Predictive equations for duodenal and absorbed saturated FA, odd and branched FA, and a large number of unsaturated FA isomers were obtained by integrating the effects of experimental factors such as the nature of the forage, the concentrate percentage, supplementation with oleaginous oils and seeds, and marine products, and their interactions.These equations are function of ingested FA and their interfering factors (forage conservation mode and botanical family, diet composition, animal factors).For the transfer of FA from duodenum to the mammary gland, the equations favor the prediction of their respective duodenal flows, but they also use ruminal digestive parameters (pH, acetate, butyrate) or dietary characteristics for odd and branched FA, or de novo synthesized FA (C4 :0 to C14 :0).Models validation was done with an external database, which allowed coupling the two models and evaluate their accuracy. Finally, we propose predictive equations for specific FA as well as FA groups of nutritional interest that can provide an approach to the INRA feed unit system to predict their milk yield responses according to different types of rations
Thivilliers, Florence. "Gels d'émusions à base d'huiles cristallisables : mécanismes de formation et propriétés rhéologiques." Bordeaux 1, 2007. http://www.theses.fr/2007BOR13426.
The formation of crystals in the dispersed phase of an oil-in-water emulsion induces a morphological modification of the droplet interfaces which become rough and rippled. This phenomenon can give rise to dramatic rheological modifications like the transition from a fluid to a solid state. We show that gelation of emulsions upon thermal treatment can be provoked by two distinct mechanisms : (i) partial coalescence caused by crystals located nearby the interfaces which irreversibly bridge neighbouring drops, and (ii) a jamming phenomenon due to surface roughness hindering the relative displacement of droplets in contact. By performing experiments on model systems, we establish that both the mechanism and kinetics of gelation are governed by the solid oil content, the drops diameter and the interface composition. In particular, we show that partial coalescence can be described as a percolation process requiring the creation of "solid versus liquid" contacts in between two drops. When submitted to a shear flow, the emulsions or gels exhibit two limiting behaviours : a macroscopic phase separation can be observed and/or a fragmented gel can be obtained with reduced level of connectivity. We study the influence of the parameters controlling the topological evolution. The variety of accessible states makes these materials suitable for applications in different industrial fields like cosmetics or food
Bayard, Mathilde. "Modulation de la cristallisation de la matière grasse laitière en phase continue ou dispersée." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0046.
Anhydrous Milk Fat (AMF) comprises more than 98% triglycerides. The diversity of the esterified fatty acids induces a complex behavior of AMF during crystallization. In addition, other minor components, either endogenously present or added upon processing modulate AMF crystallization. Nevertheless, the mechanisms underlying their mode of action are still poorly understood, making the mastery of fat crystallization difficult. Several characterization methods (NMR, X-ray diffraction, optical microscopy, differential scanning calorimetry, rheology) were implemented to screen a large set of minor components at different scales and temperatures. The approach enabled to gain knowledge about the involved mechanisms, both in bulk and in the emulsified state. Minor components modify the kinetics of AMF crystallization through their impact on the two main stages of the process, nucleation and growth. By accelerating or slowing down the rate of crystallization, they modify the nature and/or the structure of the crystal lattice and, possibly, the macroscopic properties of AMF. The impact of minor components on AMF crystallization depend on their chemical nature (length of the carbon chain, degree of unsaturation, esterification) and on their concentration. When fat is emulsified, confinement and interfacial effects come into play. Minor components modulate crystallization via the oil/water interface or via the fat phase depending on their preferential solubility, which may induce specific thermal and structural properties. On the whole, this study enables a better understanding of the factors that modulate milk fat crystallization and provides useful guidances for a better control of this key process controlling the structure and function of dairy products
Brassard, Didier. "Étude de l'impact des gras laitiers sur la capacité des lipoprotéines de haute densité à stimuler l'efflux de cholestérol." Master's thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/27759.
Reducing saturated fatty acids (SFA) in the diet is a common nutritional guideline, because SFA raise low-density lipoprotein cholesterol (LDL-C) concentrations. Low-fat dairy products are often preferred to lower SFA intake. SFA also increase high-density lipoprotein cholesterol (HDL-C) associated with a lower risk of cardiovascular disease (CVD). However, recent controlled studies indicated that HDL-C may not have a causal relationship with CVD. On the other hand, a measure of functionality, as is the cholesterol efflux capacity (CEC), could provide additional information on the role of HDL in CVD. Thus, our group began the study of the effects of dairy fats on HDL-mediated CEC (HDL-CEC) to clarify the effects of SFA on HDL. Our results showed that the SFA food source affects this functionality: a diet rich in SFA from butter increased HDL-CEC more than a diet rich in SFA from cheese. Additionally, gender seemed to modify the effects of dietary fats on HDL-CEC. The butter-rich diet increased HDL-CEC in men only, while a diet rich in monounsaturated fats increased HDL-CEC in women only. Finally, we also found an association between the increase in LDL-C and the increase in HDL-CEC after the butter-rich diet on men, suggesting a compensatory mechanism.
Lussier, Noémie. "Impact d'un procédé industriel de brassage et de refroidissement sur les propriétés texturales et rhéologiques de yogourts brassés : rôle de la teneur en matières grasses et du temps de fermentation." Master's thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/27784.
More and more research subjects are about stirred yogurt but, only few have worked on combined impacts of yogurt production at a pilot scale. The purpose of this project was to determine the combined effects of milk fat (MF) content, fermentation time (FT), type of cooling during stirring, and storage time on the physico-chemical, textural and rheological properties of stirred yogurt. The yogurts were standardized at 4.2% protein and 16.5% total solids (TS), and the MF content was adjusted to values between 0.0% and 3.9%. A fat-free yogurt with 14% TS was used as a control. The FT was set at 3, 4 and 5 hours. After fermentation, yogurt (25 kg) of each tank was stirred using a pilot system that simulated industrial production conditions (tank stirring, pumping, smoothing, cooling) and cooled using a tubular heat exchanger, causing low shear, or a plate heat exchanger, which caused high shear. Syneresis, firmness, hysteresis and apparent viscosity were measured during 34 days of storage at 4 °C. The results showed that MF content and TS had little impact on the physico-chemical, textural and rheological properties of stirred yogurts. A higher MF content reduced syneresis and increased firmness, hysteresis loop areas, and viscosity in stirred yogurts. High shear of the plate heat exchanger led to a reduction in syneresis and an increase in firmness, but without changing the viscosity. Storage led to an increase of firmness and viscosity but, syneresis did not change. The results suggest that the type of cooling system used has an important impact on rheological properties but that the presence of MF at 2.6% and higher makes the yogurt more resistant to the disruption of the protein network caused by high shear during stirring, leading to lower syneresis and higher firmness and viscosity.
Saint-Sauveur, Diane. "Propriétés immunomodulantes des protéines et peptides du lactosérum." Thesis, Université Laval, 2009. http://www.theses.ulaval.ca/2009/26519/26519.pdf.
Queguiner, Claire. "Nouvelles propriétés fonctionnelles de protéines laitières obtenues par traitements thermomécaniques d'extrusion." Montpellier 2, 1992. http://www.theses.fr/1992MON20271.
Rancourt-Bouchard, Maryka. "Impacts de la consommation de produits laitiers faibles et riches en gras sur la tension artérielle et autres facteurs de risque cardiométabolique." Master's thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/33493.
Cardiovascular disease remains one of the leading causes of death worldwide and hypertension is a major risk factor. Healthy eating plays a key role in blood pressure (BP) management. Data from observational studies suggest that consumption of dairy products, particularly those low in fat, is associated with lower BP and lower risk of developing hypertension. However, the results of clinical studies suggest a neutral effect of dairyproductconsumption on office BP. The controlled feeding study conducted as part of this memoiraimed to evaluate the effect of milk and cheese consumption on daytime ambulatory BP and other cardiometabolic risk factors. In a cross-over design, 55 participants were randomly assigned to a sequence of 3 experimental isoenergetic diets of 6 weeks each : 1) a control dairy-freediet; 2) a diet comprising 3 portions of 1% low-fat milk; and 3) a diet comprising 1 portion of cheddar cheese (31% fat) naturally enriched in -aminobutyric acid. Both ambulatory and clinical BP values were similar after each diet. In subjects with baseline ambulatory diastolic BP below the median, the milk diet significantly decreased the daytime ambulatory diastolic BP by 2 mmHg compared with the control diet. These results suggest that short-term milk and cheese consumption has an overall neutral effect on BP.
Fadul, Pacheco Liliana. "Relations entre la composition du lait et les facteurs alimentaires dans les troupeaux laitiers québécois." Doctoral thesis, Université Laval, 2016. http://hdl.handle.net/20.500.11794/27160.
The objective of this thesis was to establish the relationship between diet and milk composition, focusing on the milk fat concentration (MFC), milk urea nitrogen (MUN) and nitrogen use efficiency. For the MFC, mainly, the relationship between this component and the dietary cation-anion difference (DCAD) was studied. A database including 2 142 dairy herds from Québec was used to carry out multiple regression analysis to determine the relationship between the diet composition, including DCAD, and the MFC. With the model built, it was possible to predict between 32 and 66% of the variation of MFC depending on the stage of lactation. Despite several interactions found, an increase in the DCAD, palmitic acid supplementation and distribution in total mixed ration had a positive relationship with MFC. Whereas an increase in the proportion of concentrate had a negative effect on the MFC. The models built showed the importance of feeding management and diet composition on MFC. In addition, it showed that DCAD should be taken into account for diet formulation. In a second study, the same database was used to identify nutritional factors that may affect MUN. Contrary to what is reported in the literature, positive but also negative correlations between MUN and dietary crude protein concentration within herds on a 36-month period were obtained. To better understand these relationships, results of diet composition and performance of 100 herds with positive correlations (r > 0.69) and 100 herds with negative correlations (r < -0.44) between MUN and crude protein concentration of the diet were compared. Results showed no differences between the groups for diet composition and for performance.Which suggested that there are other than nutritional factors that can affect MUN. Results from this study did not allow to pinpoint a better context of utilization for MUN as a tool for feeding management. These results raise questions on the validity of this type of dataset for specific nutritional evaluation. Considering the results of the previous study, the last project was to better understand the characteristics of the herds with different nitrogen use efficiency by using more reliable data. Thus, 100 Québec dairy herds were visited to collect data of production, feed intake and management practices. Herds were then divided in four groups by a cluster analysis according to their nitrogen use efficiency. The comparison between these groups showed that herds with greater nitrogen use efficiency had higher average milk yield per cow. Regarding feeding strategies, more efficient herds had more energy but less crude protein in their diets than the herds of the less efficient groups. The result of the analysis also showed the importance of the dry matter intake in the nitrogen use efficiency, because herds in the greater efficiency groups had a lower intake. Although, MUN was different between the group with the high efficiency and the low efficiency, the lack of a perfect concordance between MUN and the nitrogen efficiency and between MUN and dietary crude protein may have been due in part to the small difference in the nitrogen efficiency between the two intermediate groups. Finally, in addition of reducing the risk of nitrogen pollution, herds in the higher efficiency groups had the higher incomes over feed costs. There is therefore also an economic incentive to improve nitrogen use efficiency on farms.
Akraim, Fowad. "Effet du traitement thermique des graines de lin sur la biohydrogénation ruminale des acides gras polyinsaturés et la qualité de la matière grasse du lait de vache." Phd thesis, Toulouse, INPT, 2005. http://oatao.univ-toulouse.fr/7300/1/akraim.pdf.
Mouriot, Julien. "Acides gras trans d'origine naturelle : impact sur les facteurs de risques cardiovasculaires chez l'Homme : modulation et compréhension du métabolisme de l'acide vaccénique chez la chèvre laitière." Clermont-Ferrand 1, 2009. http://www.theses.fr/2009CLF1MM06.
Trans fatty-acids (TFA) are identified as undesirable nutrients in human diets to the documented adverse effects of these fatty acids resulting from partial hydrogenation of vegetable oils (PHVO). However, TFA not only occur in PHVO, but also in the ruminant products, in particular in dairy fats. In this case, the TFA have different isomeric profile with vaccenic acid (VA, trans-11 C18:1) being the major isomer, whereas PHVO mainly contain trans-9 and trans-10 isomers of C18:1. This difference is due in the first case to bacterial hydrogenation in the rumen (R-TFA for ruminant) and in the second case to catalytic hydrogenation (IP-TFA for industrial produced). During the development of this project, no study highlighted association between the R-TFA consumption and increase in the cardiovascular disease (CVD). The first objective of my thesis was to determine the impact of human consumption of dairy fat with fatty acid profile enriched in R-TFA on the biomarkers of cardiovascular risk factor (CVD). Another objective was to study R-TFA metabolism in ruminants. To achieve the 1st objective, three specific ruminant milk fats with increasing TFA content were distributed to human volunteers during 3 weeks nutritional intervention study. Then, in a second stage, was studied the metabolism of VA in the caprine lactating mammary gland by measuring the uptake and conversion of VA to C18:2 cis-9, trans-11 (rumenic acid, RA) using a chemical tracer strategy allowing an in vivo measurement of the delta9-desaturation of VA in goats fed lipid supplements. The clinical intervention study show that a 3 weeks period of consumption of products with 63. 3% of saturated fatty-acids (SFA) and 3. 5% of R-TFA decreases significantly total cholesterol, LDL-cholesterol, LDL-cholesterol/HDL-cholesterol and the CT/HDL-cholesterol compared to commercial dairy fat consumption (72% of SFA and 2. 5% of R-TFA) in human volunteers. Dairy fats with 63. 3% of SFA and 3. 5% of R-TFA appear the optimal balanced in relation to CVD risk. The second study demonstrates in goats fed lipipd supplements that the endogenous synthesis of RA from VA in the mammary gland is the major source of this fatty-acid, since 63 to 73% of RA secreted comes from to the delta-9 desaturation of 32% of VA collected
Collard-Bovy, Christine. "Dosage des protéines du lait par immunonéphélémétrie sur supports microparticulaires : : Mise au point et applications." Nancy 1, 1988. http://www.theses.fr/1988NAN10491.
Ayala-Bribiesca, Erik. "Effect of calcium on bioaccessibility of milk fat during digestion of Cheddar-type cheeses." Doctoral thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/28167.
Cheddar cheese is recognized as an excellent source of calcium. In addition to its intrinsic nutritional value, calcium promotes lipolysis during digestion. This lipolysis enhancing effect is explained by the formation of calcium soaps with saturated long-chain fatty acids, resulting in the exposure of new substrate to the oil-water interphase of the milk fat droplets, thus enabling lipase to continue its action. On the other hand, the formation of calcium soaps reduces the absorption of saturated long-chain fatty acids. From a technological point of view, calcium plays a key role in the cheese structure as it participates in the formation of the paracasein gel. By such effects on the cheese matrix and the digestion of lipids, calcium can modify the bioavailability of the dairy fat. The objective of this project was to better understand the effect of calcium on the bioavailability of dairy fat from Cheddar cheeses, in aim to developing food matrices for controlled digestion and absorption of lipids. In a first step, Cheddar cheeses enriched with calcium by the addition of CaCl₂ were subjected to digestion in vitro. Chyme analysis showed that calcium-enriched cheeses disintegrated less rapidly than the non-enriched control but that their lipolysis progressed more rapidly, demonstrating the effect of calcium on the factors that influence lipolysis. In a second step, Cheddar cheeses were made from standardized milk with control, olein and stearin butter oils and salted with or without CaCl₂. The cheeses were digested in vitro to study the effect of calcium on lipolysis and the formation of calcium soaps from butter oils with different fatty acid profiles. Cheeses prepared with the stearin fraction (with the highest ratio of saturated long-chain fatty acids) were more resistant to physical disintegration and presented slower lipolysis than the other cheeses because of the high melting point of this fat. Cheeses enriched with calcium had higher levels of lipolysis than cheeses without enrichment. This increased lipolysis was due to the formation of calcium soaps with saturated long-chain fatty acids. These insoluble compounds could reduce the bioavailability of the fatty acids involved by preventing their absorption. To confirm the effect of calcium and type of fat on lipid bioavailability, the cheeses were subsequently used for an in vivo study. Postprandial lipemia of Wistar rats was monitored following ingestion of the cheese. The feces were analyzed to quantify the fatty acids excreted as calcium soaps. The cheeses had different effects in postprandial lipemia. Calcium enrichment led to a higher lipemic peak for the cheeses with olein, while a delayed peak was observed for cheeses with the stearin. This was explained by the increased affinity of calcium for saturated long-chain fatty acids, indirectly allowing faster lipolysis of other fatty acids, such as those with short- and medium-chains. The delay for stearin cheeses was due to their high content of saturated long-chain fatty acids, which formed soaps with calcium, thus reducing their absorption and ending up in feces. The results confirm that calcium plays an important role in intestinal digestion of dairy lipids by increasing the rate of lipolysis. However, it also limits the bioaccessibility of fatty acids by producing insoluble calcium soaps with saturated long-chain fatty acids at intestinal pH conditions. This project demonstrates that the bioavailability of lipids can be regulated by calcium in Cheddar cheese. This study demonstrates the interaction of calcium and lipids present in the dairy matrix during digestion and confirms its physiological repercussion. These effects on digestion and lipid absorption are of interest for the design of food matrices for the controlled release of liposoluble nutrients or bioactive molecules. Further research in this area will provide a better understanding of the role of foods in human health and enable the development of dairy products to control the release of nutrients to modulate metabolic responses. Keywords: Cheese, milk fat, digestion, lipolysis, calcium soaps.
Bongard, Sébastien. "Partage et libération de composés d'arôme dans des matrices laitières émultionnées et gélifiées modèles de yaourts brassés." Nantes, 2006. http://www.theses.fr/2006NANT2048.
This work aimed to sort the keys factors that modified the behavior of aroma compounds in models of stirred yogurts. Complex matrices were designed by varying the amount and the nature of emulsified fat as well as the organization of the continuous phase (emulsions vs stirred gels). Mechanical properties, structure of matrices and protein load and composition at the interface were characterized. Retention of hydrophobic aroma compounds was mainly related to the amount of liquid fat and to a lesser extent to the organization of the continuous phase. The release rate was related to the amount of liquid fat in emulsions and to the yield stress in stirred gels. Above 30 g. Kg-1 of liquid fat, partition coefficients over emulsions and stirred gels can be predicted from behavior over liquid fat and water only. Below this value, composition and organization of the continuous phase must be taken into account
Gong, Zhang Ling. "Méthodologie analytique de détermination des graisses butyriques." Compiègne, 1996. http://www.theses.fr/1996COMP925S.
Lacroix, Émilie. "Étude de l'impact des acides gras trans laitiers sur la cholestérolémie chez la femme." Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/28051/28051.pdf.
Du, Qin. "Optimisation des profils lipidiques du cerveau de rats déficients en oméga-3 au sevrage par l'utilisation de matière grasse laitière : conséquences au niveau du lipidome." Thesis, Aix-Marseille 2, 2010. http://www.theses.fr/2010AIX20717/document.
The accretion of docosahexaenoic acid (DHA) in brain membranes mainly occurs around delivery and during the first two years of life. One of the main goals of neonatal nutrition is to optimize the incorporation of n-3 long chain polyinsaturate fatty acids (LC-PUFA) into the central nervous system, including DHA. Our goal was to study the impact of several kinds of diets based on dairy-fat to improve the n-3 LC-PUFA bioconversion and DHA accretion into brain. The other endpoint was to assess if beyond the brain fatty acid profiles, the dietary intakes would bring about a wider effect such as the one that can be appreciated through a lipidomic approach.We compared the nutritional effect of dairy-fat based diets to that of palm-oil based diets in the rat reproductive model. Mother rats were made deficient in α-linoleic acid (ALA) (0.4% of fatty acids (FA) for 6 weeks prior to mating and throughout gestation and lactation. After weaning, the resulting deficient 40 rat pups of either gender were split into 4 groups and received 10% fat diets made with either 1.5%ALA palm oil blend (P1), same added with 0.12% DHA and 0.4% arachidonic acid (ARA) (P2) , 1.5% ALA dairy-fat blend (B1) or 2.5% ALA dairy-fat blend (B2). The brain, red blood cell (RBC) and plasma fatty acid profiles were analyzed and treated using multivariate statistics. B1 was superior to both palm-oil based diets to improve the brain DHA contents (14.4% increase, P < 0.05). B2 brought an additional benefit for this parameter. The brain DHA contents in males were significantly lower than for the female because of a diet x gender interaction. This effect was smoothed with the dairy-fat diets or the palm-oil based diet augmented with preformed DHA.We calculated a new fatty acid index to predict the brain DHA contents, based on the fatty acid profiles measured in RBC and plasma, and which demonstrated a better performance than the existing published index. For the first time, we showed a profound and yet unsuspected effect of diets until now on the brain lipidome (lipids molecular species), affecting about 15% of the features detected. These changes were ascribed to the cholesterol and fatty acid metabolism, and to the lipid messengers, among others.In conclusion, our data appear highly relevant to improve infant formulas. The first use of the lipidomic approach in neonatal nutrition open the paths of new researches in the area of infant nutrition
Lemaire, Marion. "L’incorporation de matière grasse laitière et de L. fermentum dans des préparations pour nourrissons programme le microbiote et la physiologie intestinale de l’adulte : étude dans un modèle miniporc." Thesis, Rennes 1, 2018. http://www.theses.fr/2018REN1B018/document.
Early postnatal nutrition programs adult health owing to its crucial role in gut microbiota colonization and host physiology development. The objective of my thesis was to investigate the consequences of dairy lipid addition with or without probiotic Lactobacillus fermentum in infant formulas on adult gut microbiota, physiology and metabolism, using Yucatan minipig as a model for humans. We demonstrated increased non-specific intestinal defences in piglets and improved intestinal endocrine and immune functions in adults submitted to a high-energy diet, which may protect them from inflammation and metabolic disorders. These effects were associated in piglets to changes in digestion and gut microbiota composition and metabolism. We observed specific and complementary effects of dairy lipids and L. fermentum, suggesting different mechanisms of action. The infant formula composition had site- and age-specific effects, the caecal microbiota being closer to the faecal one. To conclude, the addition of dairy lipids and L. fermentum in infant formulas is an effective way to improve infant formulas
Vilhena, dias de andrade Patricia. "Influence du pourcentage de concentré et de l'apport lipidique sur les flux duodénaux de lipides et sur la composition de la matière grasse laitière en réponse à l'infusion de t10,c12-CLA chez la chèvre laitière." Phd thesis, INAPG (AgroParisTech), 2006. http://pastel.archives-ouvertes.fr/pastel-00001929.
Paradis, Cloé. "Modification de la teneur en acides linoléiques conjugués du tissu adipeux du veau de boucherie au pâturage par l'apport de soya extrudé aux vaches allaitantes." Master's thesis, Université Laval, 2007. http://hdl.handle.net/20.500.11794/18956.
Ould, Hamouda Hassina. "Impact de la qualité des protéines et des lipides du régime de renutrition sur la composition en acides gras, la réponse hépatique à l'insuline, la régulation de l'homéostasie énergétique et l'inflammation, chez les rats âgés Wistar souffrant de malnutrition." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA11T019/document.
Malnutrition related to aging is often accompanied by many metabolic disorders, including the disruption of energy homeostasis (installation of insulin resistance), fragility, decreased muscle mass and immune response deficiency. Thus, the nutritional manipulation, during aging, is considered to be a solution to prevent these disorders or to treat and limit damages. Amongst the nutrients that have been widely studied, we find the quality of proteins (or amino acids), of lipids (n-3 PUFA) and micronutrients (vitamin D).The aim of this thesis is to determine the impact of undernutrition and assess the potential of the refeeding formulas containing a high content of soluble protein of milk, associated with milk fat enriched with omega3 polyunsaturated fatty acids (ALA precursor and DHA) and vitamin D, on the fatty acid (FA) of the plasma, red blood cells and brain and its consequences on markers of inflammatory status, the hepatic response to insulin, the expression of genes involved in the regulation of energy homeostasis as well as hypothalamic inflammation, in old rats previously submitted for food restrictionAs a first step, our results showed that the dietary restriction of three months, despite being only moderately ALA deficient, induced a drastic loss omega3 (ALA and derivatives LCn-3), whereas a weak increase of ARA derived from n-6 series is observed, leading to a rise of the pro-inflammatory state expressed as an increase in the ratio ARA/LCn-3.However, we have shown that the four-week-refeeding formulas containing a blend of dairy-fat, rapeseed and DHA associated with casein or milk soluble proteins, restored 1 / DHA values of the brain not previously restored by the refeeding control diet, 2 /increases the values of LCn-3 derivatives (EPA, DHA) to levels above those obtained with the control non-malnourished and refeeding diets. This increase was accompanied by a reduction in ARA values, leading to a drastic drop in plasma and red blood cells ratio ARA / EPA. These formulas show for the first time that they can induce a very significant reduction of inflammatory status compared to that usually seen in old rats and could therefore present a more general interest in prevention of ageing diseases associated or not to undernutrition.In a second step, our results showed that dietary restriction of three months resulted 1/increased expression of the insulin receptor in the hypothalamus, liver and adipose tissue, accompanied by an increase of the proinflammatory factor TNF in the hypothalamus. However, the four-weeks-refeeding produces 2/ a similar weight gain and maintains hepatic insulin sensitivity. Indeed, we showed, for the first time, that refeeding, with diets containing the blend of dairy-fat / rapeseed / DHA, would 3/ increase food intake and decrease the hypothalamic inflammation, especially with the full formula containing a mixture of high content of soluble milk proteins, associated with dairy-fat / rapeseed / DHA fortified with vitamin D
Drouin, Gaëtan. "Métabolisme et intérêt nutritionnel de l’acide docosapentaénoïque n-3 : modulation du statut tissulaire en acides gras n-3 par les lipides laitiers alimentaires chez le rat." Thesis, Rennes 1, 2018. http://www.theses.fr/2018REN1B020/document.
The optimization of tissue status in n-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) is one of the current goals in human nutrition. Indeed, many beneficial effects on human health have been demonstrated for these different n-3 LCPUFA. However, the bioconversion of these derivatives from their food precursor, α-linolenic acid, is limited in humans and it does not meet the needs of the organism. Among this family of fatty acids, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) have been widely studied in contrast to those of n-3 docosapentaenoic acid (DPA). The first objective of this work was to study the impact of dietary supplementation with DPA on fatty acid metabolism and lipid metabolism in healthy rats. For this, a method for purifying DPA with high purity and in large quantities by liquid chromatography was first established. This result helps future research of the in vivo effects of DPA, poorly commercially available. After its nutritional supplementation, DPA was incorporated into multiple tissues and it has affected the n-3 LCPUFA tissue compositions of specific organs such as the liver, heart, lung, spleen and the kidney. Thus, supplementation with DPA could be a source of EPA, DPA, and to a lesser extent DHA. Finally, compared to supplementation with EPA or DHA, DPA was the most potent n-3 LCPUFA to improve triglyceridemia and cholesterolemia in animals. This information will certainly contribute to a greater consideration of DPA both in nutritional studies and in the direction of future nutritional recommendations. The second area of research focused on the ability of a partial incorporation of dairy lipids in the diet to increase the tissue status in n-3 LCPUFA. Incorporation of dairy lipids in the diet increased DHA status in brain and retina and DPA status in the other studied tissues. In addition, the induction of conversion of n-3 LCPUFA from their precursor by dairy lipid was complementary with the DPA supplementation to increase n-3 LCPUFA status in tissues. These results fit into a context of infant nutrition, during which the incorporation of n-3 LCPUFA is maximal in nervous tissues. Thus, these results provide interesting data for both companies and health professionals to recommend infant formulas containing dairy lipids for consumption