RESUMEN
Sheep's milk (SM) is known to differ from cow's milk (CM) in nutritional composition and physicochemical properties, which may lead to different digestion behaviours. This work aimed to investigate the impact of the species (cow vs sheep) and the structure (milk vs yogurt) on the digestion of dairy products. Using an in vitro static gastrointestinal digestion model, CM, SM, cow's milk yogurt (CY) and sheep's milk yogurt (SY) were compared on particle size evolution, microscopic observations, degree of lipolysis, degree of proteolysis, specific protein degradation and calcium bioaccessibility. Species and structure affected particle size evolution during the gastric phase resulting in smaller particles for yogurts compared to milks as well as for CM products compared to SM products. Species impacted lipid composition and lipolysis, with SM products presenting higher short/medium-chain fatty acids content and higher intestinal degree of lipolysis. Proteolysis was influenced by structure, with milks showing higher intestinal degree of proteolysis compared to yogurts. Caseins were digested faster in CM, âº-lactalbumin was digested faster in SM despite its higher concentration, and during gastric digestion ß-lactoglobulin was more degraded in CM products compared to SM products and more in yogurts compared to milks. Lastly, SM products released more bioaccessible calcium than CM products. In conclusion, species (cow vs sheep) impacted more the digestion compared to the structure (milk vs yogurt). In fact, SM was different from CM mainly due to a denser protein network that might slow down the accessibility of the enzyme to its substrate which induce a delay of gastric disaggregation and thus lead to slower the digestion of the nutrients.
Asunto(s)
Digestión , Lipólisis , Leche , Tamaño de la Partícula , Proteolisis , Yogur , Animales , Digestión/fisiología , Bovinos , Yogur/análisis , Ovinos , Leche/química , Lactoglobulinas/metabolismo , Tracto Gastrointestinal/metabolismo , Productos Lácteos/análisis , Lactalbúmina/metabolismo , Caseínas/metabolismo , Caseínas/análisis , Especificidad de la Especie , Proteínas de la Leche/análisis , Proteínas de la Leche/metabolismoRESUMEN
Infant formulas (IFs) are used as substitutes for human milk and are mostly based on cow milk proteins. For sustainability reasons, animal protein alternatives in food are increasingly being considered, as plant proteins offer interesting nutritional and functional benefits for the development of innovative IFs. This study aimed to assess how a partial substitution (50%) of dairy proteins with faba bean and pea proteins influenced the digestibility of IFs under simulated dynamic in vitro digestion, which were set up to mimic infant digestion. Pea- and faba bean-based IFs (PIF and FIF, respectively) have led to a faster aggregation than the reference milk-based IF (RIF) in the gastric compartment; that did not affect the digesta microstructure at the end of digestion. The extent of proteolysis was estimated via the hydrolysis degree, which was the highest for FIF (73%) and the lowest for RIF (50%). Finally, it was apparent that in vitro protein digestibility and protein digestibility-corrected amino acid score (PDCAAS)-like scores were similar for RIF and FIF (90% digestibility; 75% PDCAAS), but lower for PIF (75%; 67%). Therefore, this study confirms that faba bean proteins could be a good candidate for partial substitution of whey proteins in IFs from a nutritional point of view, provided that these in vitro results are confirmed in vivo.
RESUMEN
Numerous calcium sources are available to enrich food, but their behavior during digestion is still unknown. This study focused on the influence of the gastro-intestinal pH, the food structure and the calcium source on the bioaccessibility of the nutrient. Four calcium sources were studied: calcium carbonate, calcium citrate malate, calcium phosphate and calcium bisglycinate. These were added to dairy matrices, containing cream and whey proteins, of different forms (liquid or gel). The kinetics of solubility and ionic calcium concentration during in vitro digestion were studied, as function of gastro-intestinal pH. All calcium sources were almost fully soluble in the gastric compartment, and then became insoluble in the intestinal phase. The level of calcium insolubilisation in the intestinal phase was not significantly influenced by the matrix structure (liquid or gel), but was more dependent on the calcium source, this effect leading to different final calcium bioaccessibility from 36% to 20%.