ROLE OF MECHANICAL FORCES IN THE STOMACH PHASE ON THE IN VITRO BIOACCESSIBILITY OF B-CAROTENE

摘要

Carotenoids are a group of fat-soluble bioactive compounds which seem to have positive effects on human health (Fernandez-Garcia et al., 2012). Since mammals need to obtain carotenoids from their diet, maximal absorption, or bioavailability of carotenoids from the food is desirable. Bioavailability is partially determined by bioaccessibility, which is the fraction of the ingested carotenoids that is incorporated into micelles and thus becomes available for absorption in the body (Hedren et al., 2002). Carotenoid bioaccessibility depends on several factors, such as the presence of oil and the matrix in which the carotenoids are embedded (Hedren et al., 2002). Carotenoids are located in chromoplasts, surrounded by a chromoplast membrane and situated in plant cells, which are in turn enclosed by a cell membrane and a cell wall (Hedren et al., 2002). To investigate the bioaccessibility of carotenoids, different in vitro digestion models have been used (Lemmens et al., 2010; Salvia-Trujillo et al., 2013). Within the stomach phase, it is however difficult to simulate the mechanical forces exactly as they occur in vivo. In most simple in vitro models, end-over-end rotations are used to mix the digest with stomach juice. The purpose of the present study is to control the mechanical forces in a simple in vitro digestion model and to evaluate whether a more controlled way of applying mechanical forces in the in vitro stomach step would allow a more accurate simulation of in vivo stomach forces as reportedin literature (Kamba et al., 2000; Pal et al., 2004). Ferrua & Singh (2010) developped in silico a 3D stomach geometry. Their results corresponded well with results found using a 2D dimensional stomach model (Pal et al., 2004) and with in vivo anatomicaldata (Marciani et al., 2001; Ferrua & Singh, 2010). In the present work, the influence of mechanical forces in the stomach phase on p-carotene bioaccessibility was investigated. More particularly, it was the objective to compare the effect of uncontrolled versus controlled mixing during in vitro stomach digestion on the microstrucrural properties of plant-based food systems during digestion and on the resulting p-carotene bioaccessibility values. Thereto, the bioaccessibility of different carrot-basedfractions was measured using two different in vitro digestion models that differed in the way mechanical forces in the stomach phase were applied (end-over-end rotation versus controlled up-and downward movement). Besides the bioaccessibility, oil droplet and particle size distributions of the digests were measured during the digestion to investigate on the one hand the effect of the mechanical forces on these sizes and on the other hand their effect on the p-carotene bioaccessibility.