Emulsion and Interface Composition Under Gastrointestinal Tract Conditions

PIERMARIA, J.; DAVID BRIAND, E.; BEAUMAL, V.; MARZE, S.; AÑÓN, M.C.; ANTON, M.

Buenos Aires

Jornada; VI Jornadas Internacionales de Proteínas y Coloides Alimentarios (JIPCA VI); 2011

UBA-UNLP-CONICET

Until now most of the research concerning food has been focused on the understanding of building and stabilising mechanisms of matrices until ingestion without taking into account their fate in the conditions of uses. On another hand nutritionists have largely addressed their studies on the composition of food in relation with their nutritional properties without considering the different scales of structure (from nano- to macro- scopic scale). Consequently, there is a growing interest in understanding and controlling the digestibility of nutrients in relation with the deconstruction process of food matrices occurring in the gastro-intestinal tract (GIT).More particularly, in oil-in-water emulsions, it lacks precise data concerning bioaccessibility and bioavailability of some lipophilic nutrients like omega-3 fatty acids, carotenoïds trough the GIT, in relation with the structure of emulsions. The design of interfaces existing between oil and water could bring some new elements in this sense. Few information concerning the physical effect of in vitro digestion models on food interfaces composed of a blend of emulsifiers exist. Therefore the aim of this study was to bring a first approach to assess the impact of in vitro reconstituted GIT phases on the structure of oil-water interfaces.We have chosen two different types of emulsifiers: amaranth proteins and egg yolk plasma to compare pure protein interfaces with a blend proteins and surfactants in the case of yolk plasma (phospholipids and proteins), at two pH (acidic and neutral). In vitro gastro-intestinal media were defined following literature and three subsequent phases were tested: saliva, gastric and intestinal media. Emulsions and model interfaces (in drop tensiometer) were then submitted successively to these media with respect to corresponding temperature, pH and duration.The main results show that important flocculation and coalescence appear from the gastric phase in the case of amaranth protein emulsions with a regular desorption of proteins commencing at the saliva phase. Emulsions made with yolk plasma seem to better resist to coalescence but a total protein desorption was noted at the intestinal phase. At the same time model interfaces made with amaranth proteins showed more important drop of interfacial tension especially at the intestinal phase as compared to yolk plasma constituted interface. This first study permitted us to stress the fact that mixed interfaces (protein-phospholipids) seems to be more resistant to GIT media and that this could enhance bioavailability of nutrients present in the oil phase.