243 research outputs found
Effect of technological treatment of the mechanisms of infant food digestion
Effect of technological treatment of the mechanisms of infant food digestion . STLOpenday
Kinetics of heat-induced denaturation of whey proteins and characterization of protein aggregates in model infant formulas
In 2018, about 60% of worldâs newborns received cow milk-based infant formulas (IF) instead of human milk (UNICEF). The process of manufacturing IF involves heat treatments altering the physicochemical properties of milk components, especially whey proteins (WP), and so the rheological properties of IF. The objective of the study was to investigate the impacts of thermal treatments on the denaturation of WP of IF, particularly for those mimicking the protein profile of human milk, and to characterize the heat-induced protein structures.Three model IF were produced with a caseins:WP ratio of 40:60 at 1.3% and 5.5% of total proteins, i.e. the protein contents at which are applied heat treatments during the manufacture of liquid or powder IF, respectively. Skimmed milk was mixed with a WP isolate, a mix of WP isolate and purified lactoferrin or a mix of both purified lactoferrin and α-lactalbumin in proportion similar to that in human milk. The kinetic of heat-induced denaturation of each WP was investigated between 67.5°C and 80°C by RP-HPLC. The heat-induced protein structures were studied by dynamic light scattering, electrophoresis and asymmetric flow field flow fractionation coupled with MALLS.The results revealed that the extent of denaturation of WP depended on the protein content and the nature of the WP within the IF. IF at 5.5% of proteins and containing ÎČ-lactoglobulin gelled for longer heating time at 80°C. At similar rate of total WP denaturation at 67.5°C and 80°C, the protein composition of the heat-induced aggregates changed between formulas, protein concentrations and heating temperatures but disulfide bonds were the main intermolecular links. The aggregates were larger and of fractal shape (dfapp=2.1) in formulas at 5.5% proteins whereas they were of spherical shape (dfapp=2.9) in formulas at 1.3% proteins.These results will give to industrials reliable data on the protein structures formed during the heat treatments of IF. The impact on digestibility will be subsequently investigated
Les préférences hédoniques et leur variabilité
Plan de la prĂ©sentation : 1. Peutâon allĂ©ger en gras les produits du commerce sans perte de prĂ©fĂ©rences ?2. Le gras indissociable du sucre dans lâunivers des biscuits 3. Un outil pour la mesure de la sensation de gras perçue applicable Ă tout le rĂ©pertoire alimentaire4. Un questionnaire pour la mesure de la prĂ©fĂ©rence visâĂ âvis du gras5. Un outil dâanalyse sensorielle pour la mesure de la prĂ©fĂ©rence visâĂ âvis du gra
Extending in vitro digestion models to specific human populations: Perspectives, practical tools and bio-relevant information
[EN] Background
In vitro digestion models show great promise in facilitating the rationale design of foods. This paper provides a look into the current state of the art and outlines possible future paths for developments of digestion models recreating the diverse physiological conditions of specific groups of the human population.
Scope and approach
Based on a collective effort of experts, this paper outlines considerations and parameters needed for development of new in vitro digestion models, e.g. gastric pH, enzymatic activities, gastric emptying rate and more. These and other parameters are detrimental to the adequate development of in vitro models that enable deeper insight into matters of food luminal breakdown as well as nutrient and nutraceutical bioaccessibility. Subsequently, we present an overview of some new and emerging in vitro digestion models mirroring the gastro-intestinal conditions of infants, the elderly and patients of cystic fibrosis or gastric bypass surgery.
Key findings and conclusions
This paper calls for synchronization, harmonization and validation of potential developments in in vitro digestion models that would greatly facilitate manufacturing of foods tailored or even personalized, to a certain extent, to various strata of the human population.Shani-Levi, C.; Alvito, P.; Andrés Grau, AM.; Assunção, R.; Barbera, R.; Blanquet-Diot, S.; Bourlieu, C.... (2017). Extending in vitro digestion models to specific human populations: Perspectives, practical tools and bio-relevant information. Trends in Food Science & Technology. 60:52-63. https://doi.org/10.1016/j.tifs.2016.10.017S52636
Flux de protéines endogÚnes dans l'intestin et métabolisme postprandial des acides aminés alimentaires chez les mammifÚres monogastriques et chez l'homme
Dietary protein quality depends on two key measures: true ileal protein digestibility and the metabolic utilization of absorbed amino acids (AA). The objectives of this study were to determine the influence of two dietary factors (antinutritional factors and peptides) on ileal endogenous protein flows; to validate the intubation technique used in humans for ileal digesta sampling; to determine the postprandial metabolic utilization of dietary AA depending on their delivery form and to assess the validity of the growing pig for predicting true ileal protein digestibility in the adult human. Investigations were undertaken in the growing rat, growing pig and adult human. Ileal digesta were collected from euthanised rats, post valve T-caecum cannulated pigs, and naso-ileal intubated conscious adult humans. Ileal endogenous nitrogen (N) and AA were measured using a protein-free (PF) diet, diets containing 15N-labelled casein in the intact (C) or hydrolysed (HC) form, or a diet based on free AA (diet A), for which some dispensable AA were omitted to allow a direct determination of their endogenous flows. Digesta centrifugation and ultrafiltration (diet HC) allowed for the determination of ileal endogenous protein flows and the extent of tracer (15N) recycling. Antinutritional factors from a crude extract of kidney beans (Phaseolus vulgaris), when given at amounts commonly ingested in practice, enhanced ileal endogenous protein flows (rats, PF diet). After adaptation to the diet, body N balance per se did not influence ileal endogenous protein flows (rats, diets PF and A) but dietary peptides led to greater ileal endogenous AA and N flows compared with a protein-free diet. Dietary peptides (HC), compared with peptides naturally released in the gut during protein digestion (C), did not enhance ileal endogenous protein flows (rats, pigs, and humans). The extent of tracer recycling, however, was maximal in frequently-fed rats, lower in meal-fed pigs and minimal in meal-fed humans (65, 21, and 11% of 15N-labelled ileal endogenous proteins, respectively). Naso-ileal intubation for ileal digesta sampling in humans was shown to be an accurate method and evidence was obtained supporting the growing pig as a valid model for predicting true ileal protein digestibility in the adult human. Finally, the form of delivery of dietary AA (from HC or C) influenced the postprandial metabolic fate of dietary AA, especially in terms of AA catabolism kinetics. However, the overall nutritional value of C and HC were similar.La qualité nutritionnelle des protéines alimentaires dépend de deux paramÚtres clés : la digestibilité iléale vraie et l'utilisation métabolique des acides aminés (AA) absorbés. Les objectifs de cette étude étaient de déterminer l'influence de deux facteurs alimentaires (facteurs antinutritionnels et peptides) sur les flux iléaux de protéines endogÚnes; de valider la technique d'intubation utilisée chez l'homme pour prélever des effluents iléaux; de comparer le métabolisme postprandial d'AA alimentaires suivant leur forme d'ingestion; d'évaluer la validité du modÚle porc pour prédire la digestibilité protéique chez l'homme. Les investigations se sont déroulées chez le rat, le porc et l'homme. Les effluents iléaux étaient collectés chez le rat aprÚs euthanasie, chez le porc vivant équipé d'une canule en aval de la valve iléo-caecal et chez l'homme conscient équipé d'une sonde naso-iléale. L'azote (N) et les AA endogÚnes iléaux étaient déterminés suite à un repas protéiprive (PP), un repas contenant de la caséine, intacte (C) ou hydrolysée (HC), marquée avec l'isotope stable 15N ou un repas à base d'AA libres (A) mimant la composition de la caséine et privé de certains AA non essentiels afin de mesurer directement leur flux endogÚnes. De plus, la centrifugation et ultrafiltration des effluents HC permettaient de déterminer les protéines endogÚnes iléales et le recyclage d'N alimentaire (15N). Les facteurs antinutritionnels issus d'un extrait brut de haricots (Phaseolus vulgaris), ingérés au niveau habituel de consommation chez l'homme, augmentaient les flux iléaux de protéines endogÚnes (rat, repas PP). AprÚs adaptation au repas, le bilan azoté corporel per se n'avait pas d'influence sur les flux iléaux de protéines endogÚnes (rat, repas PF et A) mais les peptides alimentaires (repas HC) augmentaient les flux iléaux d'AA et N endogÚnes par rapport au repas PP. Les peptides alimentaires (HC), comparés aux peptides libérés naturellement dans l'intestin au cours de la digestion (C), n'augmentaient pas les flux iléaux de protéines endogÚnes (rat, porc, homme). Le recyclage d'N alimentaire dans les protéines endogÚnes était maximal chez le rat nourri en continu, plus faible chez le porc nourri en aigu et minimum chez l'homme nourri en aigu (respectivement : 65, 21 et 11%). Par ailleurs, ces recherches ont montré que l'intubation naso-iléale utilisée pour prélever des effluents iléaux chez l'homme était une méthode juste et que le porc était un modÚle valide pour prédire la digestibilité iléale vraie chez l'homme. Enfin, la forme d'ingestion des AA alimentaires (HC ou C) influençaient le devenir métabolique des AA alimentaires, en particulier par rapport aux cinétiques de catabolisme des AA. Cependant, la valeur nutritionnelle était, au final, similaire pour HC et C
Animal models for determining amino acid digestibility in humans â a review
Animal models have been commonly used for determining amino acid digestibility in humans. This allows digestibility assays to be undertaken more efficiently than those undertaken using humans directly. The laboratory rat, usually considered as a suitable animal model, has been widely used, especially as the rat is easy to raise and relatively inexpensive to house. Although more technically demanding, the pig has also been promoted as a useful model for human nutrition studies. It may be a better model than the rat, as it is a meal eater, its upperdigestive tract is anatomically and physiologically closer to that of humans and it eats most foods consumed by humans. Amino acid digestibility may be determined either at the faecal or the ileal level, the latter being considered the most accurate. This contribution evaluates the suitability of the rat and pig as animal models for assessing ileal and faecal amino acid digestibility in humans. The drawbacks and advantages of using these animal models are discussed. The review is based mainly on results from controlled studies comparing bothspecies; however, as the number of these studies is limited, data from indirect comparisons also provide insight
Impact des procédés de transformation sur la digestion du lait maternel et des formules infantiles par le nouveau-né.
Ce numĂ©ro est constituĂ© dâarticles issus du colloque « Alimentation pĂ©rinatale, alimentation des sĂ©niors: spĂ©cificitĂ©s, impact du microbiote », organisĂ© le 28 mars 2018 Ă Paris.Despite the efforts made over the last decades to bring the composition of infant formulas closer to thatof human milk, important differences in composition and structure of the constituents remain betweenthese two foods. The human milk, true "gold standard" for the feeding of the newborn, has nativestructures (casein micelle, fat globule) which are modified by the technological treatments used in themanufacture of infant formulas. These changes result in behavioral differences between the twoproducts in the digestive tract of the newborn (faster gastric emptying for human milk, differences inkinetics of hydrolysis of proteins and lipids). The heat treatments used in the production of formulas leadto the denaturation and aggregation of milk proteins affecting their resistance to the action of digestiveenzymes. Caseins become more resistant to hydrolysis while serum proteins are more sensitive tohydrolysis. Homogenization transforms the fat globule of milk of several microns of diameter into submicronlipid droplets and thus increases the specific surface area available for gastric lipase leading toan acceleration of lipolysis. The physiological consequences for the newborn remain to be establishedbut preliminary work shows that these changes affect the maturation of the immune system and thestructuring of the intestinal microbiota.MalgrĂ© les efforts rĂ©alisĂ©s ces derniĂšres dĂ©cennies pour rapprocher la composition des formulesinfantiles de celle du lait humain, dâimportantes diffĂ©rences de composition et de structure desconstituants demeurent entre ces deux aliments. Le lait humain, vĂ©ritable « gold standard » pourlâalimentation du nouveau-nĂ© prĂ©sente des structures natives (micelle de casĂ©ines, globule gras) quisont modifiĂ©es par les traitements technologiques utilisĂ©s lors de la fabrication des formules infantiles.Ces modifications se traduisent par des diffĂ©rences de comportement entre les deux produits dans letube digestif du nouveau-nĂ© (vidange gastrique plus rapide pour le lait humain, cinĂ©tiques dâhydrolysedes protĂ©ines et des lipides diffĂ©rentes). Les traitements thermiques utilisĂ©s lors de la fabrication desformules infantiles entrainent la dĂ©naturation et lâagrĂ©gation des protĂ©ines laitiĂšres affectant leurrĂ©sistance Ă lâaction des enzymes digestives. Les casĂ©ines deviennent plus rĂ©sistantes Ă lâhydrolysetandis que les protĂ©ines sĂ©riques y sont plus sensibles. LâhomogĂ©nĂ©isation transforme le globule grasdu lait de plusieurs microns de diamĂštre en petites gouttelettes lipidiques sub-microniques et augmenteainsi la surface spĂ©cifique disponible pour la lipase gastrique entrainant une accĂ©lĂ©ration de la lipolyse.Les consĂ©quences physiologiques pour le nouveau-nĂ© restent Ă Ă©tablir mais des travaux prĂ©liminairesmontrent que ces modifications affectent la maturation du systĂšme immunitaire et la structuration dumicrobiote intestinal
A cidade asilo: crimes de guerra e crimes sociais
Resenha a
SHOHAM, Liad. Asylum city: a novel. Trans. Sara Kitai. New York: Harper, 2014
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