Méthode d'apprentissage pour la classification à partir d'exemples positifs

National audienceCet article présente une méthode d'apprentissage générique et non supervisée à partir d'une seule base d'exemple positif, pour la classification. Le système est formalisé dans un cadre probabiliste. Nous proposons une méthode originale pour approximer la densité de probabilité de la fonction de vraisemblance correspondant aux évènements dit normaux, en utilisant un modèle parcimonieux basé sur des fonctions noyaux. Ce modèle présente l'avantage des méthodes non-paramétriques tout en limitant le coût algorithmique souvent important qui leur est lié. La classification est ensuite effectuée à partir de cette approximation grâce à une notion de confiance. La méthode sera comparée à celle des One Class SVM et testée dans le cas de la détection d'événements rares liés au trafic routier

Impact of tannin supplementation on proteolysis during post-ruminal digestion in wethers using a dynamic in vitro system: a plant (Medicago sativa) digestomic approach

The aim of this study was to characterize the effects of tannins on plant protein during sheep digestion, using a digestomic approach combining in vivo (rumen) conditions and an in vitro digestive system (abomasum and small intestine). Ruminal fluid from wethers infused with a tannin solution or water (control) was introduced into the digester, and protein degradation was followed by LC-MS/MS. Tannin infusion in the rumen led to a clear decrease in protein degradation-related fermentation end-products, whereas RuBisCo protein was more abundant than in control wethers. In the simulated abomasum, peptidomic analysis showed more degradation products of RuBisCo in the presence of tannins. The effect of RuBisCo protection by tannins continued to impact Rubisco digestion into early-stage intestinal digestion, but was no longer detectable in late-stage intestinal digestion. The peptidomics approach proved a potent tool for identifying and quantifying the type of protein hydrolyzed throughout the gastrointestinal tract

Nutrient bioaccessibility is reduced in Elderly with oral deficiency combining in vitro mastication and digestive approaches

The first stage of digestion of solid foods begins with the food oral processing. The way in which the food bolus formation is achieved during mastication will define further digestive steps and consequently nutrient bioavailability. This work was designed to study the impact of masticatory deficiency, frequently observed in elderly population, combined with aged digestive characteristics on nutrients bioaccessibility after ingestion of a meat model food. Four combinations of oral and gastric digestive conditions were simulated: in vitro food boluses were obtained after normal or deficient mastication by programming the mastication simulator AM2 and were digested in an in vitro dynamic digester (DIDGI®) mimicking adult or elderly physiological gastric conditions. Physical characterization of food bolus material was obtained with granulometry and rheological measurements. Biochemical characteristics of the liquid phase of the bolus (lipids/proteins oxidation, free-iron/peptides release in liquid phase) were measured for nutrient bioaccessibility assessments. The kinetics of release of lipids, proteins and peptides from the food matrix during gastric digestion were assessed in digesta (collected after 30, 60, 90, 120 and 150min) and analyzed as the area under the curve of nutrient appearance. Results showed that (1) food bolus after deficient mastication were harder, more cohesive and less disorganized, and with a greater proportion of large particles (2) deficient mastication resulted in a reduced bolus ioaccessibility of free -iron and peptides (3) deficient mastication slightly impacted nutrient bioaccessibility in gastric digesta after adult digestive conditions, probably balanced by the gastric enzyme activity and acidic conditions (4) def icient mastication combined with the elderly digestive conditions delayed the release of nutrients in the gastric compartment and did not reach the threshold obtained during adult digestion. Obviously for designing specific food for elderly, the oral stage has to be carefully considered to fulfill the specific needs of the elderly population whom increase dramatically

Antioxidant supplementationis ineffective to reducethe frequency of pse-like zones in porkhams

International audienceThe frequency of pork hams with PSE-like zones is a major issue for the processed meat sector in France, despite recent improvements in the slaughter techniques and systematic sorting on the ultimate pH value of hams. Halothane genotype, still widespread in its heterozygous form, may play a significant role in this issue [1]. On the other hand, a recent work described at a molecular level a possible link between oxidative stress and the specific development of PSE-like zone [2]. From this hypothesis, an experimental design was carried out at the IFIP Experimental Station to evaluate the effect of antioxidant supplementation in pig diet on the appearance of PSE-like zone and more generally on the overall ham quality before and after cooking process

Quantification of peptides released during in vitro digestion of cooked meat

International audienceWe aimed to identify and quantify the peptides generated during in vitro digestion of cooked meat by liquid chromatography coupled with high resolution mass spectrometer. A total of 940 non-redundant peptides in the gastric compartment and 989 non-redundant peptides in the intestinal compartment were quantified and identified. Among the 71 different proteins identified, 43 meat proteins were found in the two digestive compartments, 20 proteins were specific to the gastric compartment and 8 proteins to the intestinal compartment. In terms of estimation, the proteins involved in muscle contraction and structure were preferentially enzymatically hydrolyzed in the small intestine. The effect of cooking provided different but less clear patterns of digestion. To the best of our knowledge, this constitutes the highest number of peptides identified in beef meat digests and provides a comprehensive database for meat protein digestion associated with cooking conditions. Such quantitative and qualitative differences may have important nutritional consequences

Nutrient bioaccessibility is reduced in Elderly with oral deficiency combining in vitro mastication and digestive approaches

Theme 6 6.4 Impact of Food Oral Processing on health benefitsThe first stage of digestion of solid foods begins with the food oral processing. The way in which the food bolus formation is achieved during mastication will define further digestive steps and consequently nutrient bioavailability.This work was designed to study the impact of masticatory deficiency, frequently observed in elderlypopulation, combined with aged digestive characteristics on nutrients bioaccessibility after ingestion of a meat model food. Four combinations of oral and gastric digestive conditions were simulated: in vitro food boluses were obtained after normal or deficient mastication by programming the mastication simulator AM2 and were digested in an in vitro dynamic digester (DIDGI®) mimicking adult or elderly physiological gastric conditions. Physical characterization of food bolus material was obtained with granulometry and rheological measurements. Biochemical characteristics of the liquid phase of the bolus (lipids/proteins oxidation, free-iron/peptides release in liquid phase) were measured for nutrient bioaccessibility assessments. The kinetics of release of lipids, proteins and peptides from the food matrix during gastric digestion were assessed in digesta (collected after 30, 60, 90, 120 and 150min) and analyzed as the area under the curve of nutrient appearance. Results showed that (1) food bolus after deficient mastication were harder, more cohesive and less disorganized, and with a greater proportion of large particles (2) deficient mastication resulted in a reduced bolus ioaccessibility of free -iron and peptides (3) deficient mastication slightly impacted nutrient bioaccessibility in gastric digesta after adult digestive conditions, probably balanced by the gastric enzyme activity and acidic conditions (4) deficient mastication combined with the elderly digestive conditions delayed the release of nutrients in the gastric compartment and did not reach the threshold obtained during adult digestion. Obviously for designing specific food for elderly, the oral stage has to be carefully considered to fulfill the specific needs of the elderly population whom increase dramatically

Development of meat models with fiber enrichment adapted to masticatory deficiency in Elderly

International audienc

Reduced In vitro nutrient bioaccessibility after gastric digestion in elderly presenting a deficient mastication

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Label-free study of peptides released during in vitro digestion of bovine cooked meat

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