Nutrition et Sciences des aliments

L'industrie du vin québécois a connu une forte croissance au cours des dernières années. Néanmoins, bien que la qualité des vins ait énormément augmentée, la production vinicole à partir de cépages hybrides interspécifiques demeure un défi, notamment en raison de leur composition chimique, qui demeure peu connue et différente des cépages traditionnels. Afin d'optimiser l'utilisation des cépages hybrides interspécifiques en production vinicole nordique, nous avons caractérisé les composés volatiles dans les moûts et les pellicules des baies ainsi que dans les vins des cépages Frontenac, Marquette, Maréchal Foch, Sabrevois et St. Croix par GC-MS(TOF)-SPME. Plusieurs classes de composés ont été dosés telles que des C6, des terpènes, des C13-norisoprénoïdes ainsi que des phénols volatils. et des différences importantes ont été trouvées entre les variétés. Des applications pratiques aux résultats obtenus sont proposées pour l'industrie.

Obesity is a problem in Nord America. Recent studies have demonstrated that ingestion of certain probiotics (Lactobacillus, Bifidobacterium) could reduce metabolic syndrome. Presently, no cheese or yogurt has been developed to contain probiotics able to reduce metabolic syndrome. The use of new probiotic strains having this functional propriety will be a great interest in dairy products. However, to maintain a high concentration of probiotic to have this benefic effect, the mesophilic and thermophilic starters used for the production of cheese and yogurt must not reduce the viability of probiotic. The probiotic must not affect the starter to reduce the acidification and the development of flavors. The objective of this study was to determinate the biocompatibility between 33 new probiotic strains isolated from feces and dairy products with four commercial mesophilic strains and three thermophiles starters by using the automatized spectrophotometry. Among of these 33 strains, three o...

Recent studies have shown that, the ingestion of specific probiotics (Lactobacillus, Bifidobacterium) can reduce the metabolic syndrome in humans due to their anti-inflammatory effects. No cheeses containing anti-inflammatory probiotics are currently available in Canada. In order to show beneficial effects, probiotics must maintain good viability during the production and ripening of cheese. The objective of this study was to successfully incorporate new probiotic isolates strains with anti-inflammatory effects in low fat Cheddar cheese. Three Lactobacillus and two Bifidobacterium strains isolated from infants or adults feces were selected. These strains were identified by 16S genetic identification, the lactis subspecis of Bifidobacterium animalis were confirmed by specific Q-PCR primers and the subspecis of Lactobacillus strains were confirmed by RpoB primers. The anti-inflammatory effects of these new isolate strains were evaluated in vitro using murine macrophage cell line J774....

Chronic Inflammation can play an important role in the development of the pathogenesis related with obesity. It has been demonstrated that some probiotics (Lactobacillus, Bifidobacterium) can prevent obesity and inflammation by reducing the metabolic endotoxemia, by inhibiting the production of pro-inflammatory cytokines and by shaping the gut microbiota (commensal bacteria). No dairy product containing anti-inflammatory and anti-obesity probiotics are currently available in North America. The viability of probiotic is important during the manufacture and the storage of dairy product since cheese (50 g) and yogurt (100 g) must contain at least 109 colony forming unity (cfu) of the specific probiotic strain with health claims.
The objective of this study was to determinate anti-inflammatory (in vitro) & anti-obesity (in vivo) effects of new probiotics and their viability during production and storage of non-fat yogurt and low-fat Cheddar cheese. Five probiotics isolated from faeces and raw milk, Bifidobacterium animalis ssp lactis (Bf141, Bf26), Lactobacillus (Lb.) casei/paracasei (L79), Lb. rhamnosus (Lb102) and Lb. plantarum (Lb38), genetically identified, were used. A cell model of inflammation (macrophages) and a mouse model of diet-induced obesity (obesogenic diet) were used. The heat-killed of probiotic strains induced a significant decrease in NO production and were able to increase cytokine IL-10 production (except L79) in macrophages. The body weight gain and epididymal, inguinal and retroperitoneal white adipose tissue masses in mice were more reduced with probiotics milks than control milk without probiotic. At the beginning of the cheese ripening period, all probiotic candidates were at the targeted count (109 per 50 g portion, based on health claim regulations for probiotic foods). The counts of both bifidobacteria isolates dropped below 109 during cheese ripening, while the lactobacilli counts remained stable or increased. Yogurts were formulated to contain 1.0 × 107 cfu g-1 of probiotic candidate for at least 30 days of storage. After 60 days, this count was maintained in the case of lactobacilli, but not in the case of bifidobacteria. Studies are in process to evaluate the effects of these probiotics on the parameters associated with inflammation (cytokines and LPS levels) and on the composition of gut microbiota.

Several studies have demonstrated that the gut microbiota as one of the most origin of metabolic disorders such as obesity and type 2 diabetes. Western obesogenic diet (i.e. rich in saturated/trans fat and simple sugars and poor in fibers) can importantly alter gut microbiota (i. e. dysbiosis) leading to the production of pro-inflammatory cytokines and metabolic endotoxemia, therefore promoting metabolic disorders. To counteract these negative effects, probiotics (Lactobacillus, Bifidobacterium) have been used to shaping the gut microbiota (commensal bacteria) and then prevent inflammation and obesity. No study has compared, until now, the anti-obesity effect of new probiotic strains contained in milk and yogurt.
The objective of this study was to compare the anti-obesity (in vivo) effect of new probiotics in yogurt and milk and their survival after digestion. Two probiotics isolated from faeces and raw milk, Bifidobacterium animalis ssp. lactis (Bf141) and Lactobacillus rhamnosus (Lb102), genetically identified, were used. Both freezing-drying strains were added individually in skim milk and non-fat yogurt. The population of each strain was 1 x 109 cfu per serving. Male mice fed with High-Fat High-Sucrose (HFHS) were treated by daily gavage with yogurt or milk with and without probiotic (WP) for 8 weeks. Body weight gain, epididymal white adipose tissue weight (eWAT) and blood glucose concentration (glycaemia) were determined as well as the survival of probiotics after digestion.
The both probiotic strains survived to the gastrointestinal passage. Bf141 was more resistant than Lb102 to gastrointestinal transit, whether fed in milk or yogurt, but the post-transit counts of both probiotic isolates remained above 1 x 108 cfu g-1. The body weight gain, eWAT mass and blood glucose concentration in mice fed with high-fat high-sucrose diet were more reduced with probiotics milks (Bf141 and Lb102) than with control WP milk. The anti-obesity effect was greater when the probiotic was delivered in milk rather than yogurt. These probiotic strains had any anti-obesity effect in yogurt whereas weight gain, fat mass and plasma glucose in mice were reduced similarly with Bf141 and Lb102 in milk. In this study, milk was a better vector than yogurt for probiotic bacteria with anti-obesity effect. Studies are in process to evaluate the effects of these probiotics on inflammation (cytokines, LPS) and on the composition of gut microbiota.

Low levels of high-density lipoprotein (HDL) cholesterol constitutes a major risk factor for atherosclerosis. Recent studies from our group reported a genetic association between the WW domain-containing oxidoreductase (WWOX) gene and HDL cholesterol levels. Here, through next-generation resequencing, in vivo functional studies and gene microarray analyses, we investigated the role of WWOX in HDL and lipid metabolism. Using next-generation resequencing of the WWOX region, we first identified 8 variants significantly associated and perfectly segregating with the low-HDL trait in 2 multigenerational French Canadian dyslipidemic families. To understand in vivo functions of WWOX, we used liver-specific Wwox(hep-/-) and total Wwox(-/-) mice models, where we found decreased ApoA-I and Abca1 levels in hepatic tissues. Analyses of lipoprotein profiles in Wwox(-/-), but not Wwox(hep-/-) littermates, also showed marked reductions in serum HDL cholesterol concentrations, concordant with the lo...

It is well accepted that both apolipoprotein A-I (apoA-I) and ABCA1 play crucial roles in HDL biogenesis and in the human atheroprotective system. However, the nature and specifics of apoA-I/ABCA1 interactions remain poorly understood. Here, we present evidence for a new cellular apoA-I binding site having a 9-fold higher capacity to bind apoA-I compared with the ABCA1 site in fibroblasts stimulated with 22-(R)-hydroxycholesterol/9-cis-retinoic acid. This new cellular apoA-I binding site was designated "high-capacity binding site" (HCBS). Glyburide drastically reduced (125)I-apoA-I binding to the HCBS, whereas (125)I-apoA-I showed no significant binding to the HCBS in ABCA1 mutant (Q597R) fibroblasts. Furthermore, reconstituted HDL exhibited reduced affinity for the HCBS. Deletion of the C-terminal region of apoA-I (Delta187-243) drastically reduced the binding of apoA-I to the HCBS. Interestingly, overexpressing various levels of ABCA1 in BHK cells promoted the formation of the HCBS. The majority of the HCBS was localized to the plasma membrane (PM) and was not associated with membrane raft domains. Importantly, treatment of cells with phosphatidylcholine-specific phospholipase C, but not sphingomyelinase, concomitantly reduced the binding of (125)I-apoA-I to the HCBS, apoA-I-mediated cholesterol efflux, and the formation of nascent apoA-I-containing particles. Together, these data suggest that a functional ABCA1 leads to the formation of a major lipid-containing site for the binding and the lipidation of apoA-I at the PM. Our results provide a biochemical basis for the HDL biogenesis pathway that involves both ABCA1 and the HCBS, supporting a two binding site model for ABCA1-mediated nascent HDL genesis.