Personne : Britten, Michel
En cours de chargement...
Date de naissance
Projets de recherche
Nom de famille
Université Laval. Département des sciences des aliments
Résultats de recherche
Voici les éléments 1 - 6 sur 6
- PublicationRestreintDetection and quantification of capsular exopolysaccharides from Streptococcus thermophilus using lectin probes(American Dairy Science Association, 2010-02-26) Vadeboncoeur, Christian; Moineau, Sylvain; Robitaille, Gilles; Britten, Michel; St-Gelais, DanielThe aim of this work was to use fluorescently labeled lectins to develop a convenient and reliable method to determine the relative abundance of capsular polysaccharides (CPS) at the surface of Streptococcus thermophilus MR-1C cells. Fluorescein isothiocyanate–labeled peanut agglutinin isolated from Arachis hypogaea was found to interact specifically with the CPS of Strep. thermophilus MR-1C. This labeled lectin was then used as an effective probe to detect and quantify CPS. A fluorescence-based lectin-binding assay was successfully applied to follow the accumulation of CPS during the growth of Strep. thermophilus MR-1C in milk and in M17 broth supplemented with lactose. Our results showed that in both media, CPS production by Strep. thermophilus MR-1C began during the exponential phase of growth and continued for several hours after the culture reached the stationary growth phase.
- PublicationAccès libreEffect of calcium enrichment of Cheddar cheese on its structure, in vitro digestion and lipid bioaccessibility(Oxford : Elsevier Ltd., 2015-09-28) Ayala-Bribiesca, Erik; Lussier, Martine; Chabot, Denise; Turgeon, Sylvie; Britten, MichelThe nutritional role of cheese is usually reduced to its composition, often neglecting the effect that the matrix can have on digestion. The purpose of this study was to establish a link between the characteristics of Cheddar cheeses with different calcium levels and the impact on cheese in vitro digestion. Curds were enriched with CaCl2 during the salting step to produce control, high-calcium, and very high-calcium cheeses. Cheese composition, texture and structure were characterized, and physical disintegration and lipolysis were monitored during in vitro digestion. Cheese hardness increased with higher calcium content. This resulted in a slower disintegration during in vitro digestion. Despite showing faster disintegration, the control cheese had the slowest lipolysis progression. The results suggest that lipolysis depends on calcium content and the matrix modulating the access of enzymes to their substrates. Further studies should provide a better understanding of the calcium–matrix interaction affecting lipid bioaccessibility.
- PublicationAccès libreEffect of calcium on fatty acid bioaccessibility during in vitro digestion of Cheddar-type cheeses prepared with different milk fat fractions(Urbana, Ill. : American Dairy Science Association, 2017-03-18) Ayala-Bribiesca, Erik; Britten, Michel; Turgeon, SylvieCalcium plays an important role in intestinal lipid digestion by increasing the lipolysis rate, but also limits fatty acid bioaccessibility by producing insoluble Ca soaps with long-chain fatty acids at intestinal pH conditions. The aim of this study was to better understand the effect of Ca on the bioaccessibility of milk fat from Cheddar-type cheeses. Three anhydrous milk fats (AMF) with different fatty acid profiles (olein, stearin, or control AMF) were used to prepare Cheddar-type cheeses, which were then enriched or not with Ca using CaCl2 during the salting step. The cheeses were digested in vitro, and their disintegration and lipolysis rates were monitored during the process. At the end of digestion, lipids were extracted under neutral and acidic pH conditions to compare free fatty acids under intestinal conditions in relation to total fatty acids released during the digestion process. The cheeses prepared with the stearin (the AMF with the highest ratio of long-chain fatty acids) were more resistant to disintegration than the other cheeses, owing to the high melting temperature of that AMF. The Ca-enriched cheeses had faster lipolysis rates than the regular Ca cheeses. Chromatographic analysis of the digestion products showed that Ca interacted with long-chain fatty acids, producing Ca soaps, whereas no interaction with shorter fatty acids was detected. Although higher Ca levels resulted in faster lipolysis rates, driven by the depletion of reaction products as Ca soaps, such insoluble compounds are expected to reduce the bioavailability of fatty acids by hindering their absorption. These effects on lipid digestion and absorption are of interest for the design of food matrices for the controlled release of fat-soluble nutrients or bioactive molecules.
- PublicationAccès librePostprandial lipemia and fecal fat excretion in rats is affected by the calcium content and type of milk fat present in Cheddar-type cheeses(New York, NY : Elsevier Science, 2018-03-21) Ayala-Bribiesca, Erik; Turgeon, Sylvie; Pilon, Geneviève; Britten, Michel; Marette, AndréThe aim of this study was to better understand the effect of calcium on the bioavailability of milk lipids from a cheese matrix using a rat model. Cheddar-type cheeses were manufactured with one of three types of anhydrous milk fat, control, olein or stearin, and salted with or without CaCl₂. The cheeses were fed to rats and postprandial lipemia was monitored. Feces were analyzed to quantify fatty acids excreted as calcium soaps. Higher calcium concentration in cheese caused a higher and faster triacylglycerol peak in blood, except for cheeses containing stearin. Furthermore, calcium soaps were more abundant in feces when the ingested cheese had been enriched with calcium and when the cheese was prepared with stearin. Increased lipid excretion was attributable to the affinity of saturated long-chain fatty acids for calcium. Results showed that lipid bioaccessibility can be regulated by calcium present in Cheddar cheese. This study highlights the nutritional interaction between calcium and lipids present in the dairy matrix and confirms its physiological repercussions on fatty acid bioavailability.
- PublicationRestreintFat-free yogurt made using a galactose-positive exopolysaccharide-producing recombinant strain of Streptococcus thermophilus(American Dairy Science Association, 2010-01-08) Vadeboncoeur, Christian; Moineau, Sylvain; Robitaille, Gilles; Britten, Michel; Tremblay, André; St-Gelais, DanielTo prevent textural defects in low-fat and fat-free yogurts, fat substitutes are routinely added to milk. In situ production of exopolysaccharides (EPS) by starter cultures is an acknowledged alternative to the addition of biothickeners. With the aim of increasing in situ EPS production, a recombinant galactose-positive EPS(+) Streptococcus thermophilus strain, RD-534-S1, was generated and compared with the parent galactose-negative EPS(+) strain RD-534. The RD-534-S1 strain produced up to 84 mg/L of EPS during a single-strain milk fermentation process, which represented 1.3 times more than the EPS produced by strain RD-534. Under conditions that mimic industrial yogurt production, the starter culture consisting of RD-534-S1 and (EPS(-)) Lactobacillus bulgaricus L210R strain (RD-534-S1/L210R) led to an EPS production increase of 1.65-fold as compared with RD-534-S1 alone. However, the amount of EPS produced did not differ from that found in yogurts produced using an isogenic starter culture that included the parent S. thermophilus strain RD-534 and Lb. bulgaricus L210R (RD-534/L210R). Moreover, the gel characteristics of set-style yogurt and the rheological properties of stirred-style yogurt produced using RD-534-S1/L210R were similar to the values obtained for yogurts made with RD-534/L210R. In conclusion, it is possible to increase the production of EPS by ropy S. thermophilus strains through genetic engineering of galactose metabolism. However, when used in combination with Lb. bulgaricus for yogurt manufacture, the EPS overproduction of recombinant strain is not significant.
- PublicationAccès libreIdentification of texture parameters influencing commercial cheese matrix disintegration and lipid digestion using an in vitro static digestion model(New York, NY : Elsevier Science Pub. Co., 2019-03-26) Guinot, Léa; Rioux, Laurie-Eve; Labrie, Steve; Britten, Michel; Turgeon, SylvieCheese characteristics, such as composition or textural properties, can impact the matrix degradation rate which could modulate the bioaccessibility of fatty acids during digestion. The aim of this study was to identify texture parameters influencing cheese degradation in a gastrointestinal environment. A static in vitro digestion model has been used on nine commercial cheeses: young and aged cheddar, regular and light cream cheese, parmesan, feta, camembert, mozzarella, and sliced processed cheese. At the end of gastric digestion, camembert and mozzarella presented the lowest matrix disintegration whereas aged cheddar, regular and light cream cheeses showed the highest. For all cheeses, the fatty acid release was fast during the first 30 min of duodenal digestion and slowed down afterwards. A partial least square regression revealed that springiness, cohesiveness, and hardness were negatively correlated to the rate of cheese disintegration during gastric digestion. In addition, textural parameters were not correlated with free fatty acid release. By modulating cheese texture, it could be possible to influence matrix disintegration during gastrointestinal digestion which could have an impact on lipids release.