科学系利用VideometerLiq液体多光谱成像系统，发表了题为A semi dynamic in vitro digestion study of milk protein concentrate dispersions structured with different polysaccharides的文章。VideometerLiq液体多光谱成像系统是新型液体成像系统。

A semi dynamic in vitro digestion study of milk protein concentrate dispersions structured with different polysaccharides

Abstract

Hydrocolloids are often added as functional ingredients in foods, to better design the structure of the matrix and ensure food quality and optimal sensory properties. However, much less is known about their influence on the physical and chemical changes during gastric digestion. In this study, semi- continuous in vitro gastric digestion was applied on a model food system, prepared with milk protein concentrate (MPC) (3% w/v) and 1% alginate, pectin, guar gum, as well as a 1:1 mixture of alginate and pectin. The dynamics during simulated gastric digestion were observed by measuring particle size distributions, structuring at various length scales, as well as by evaluating differences in protein  breakdown. Immediately after contact with the simulated gastric fluids, all samples showed extensive  aggregation and formation of different structures. MPC control dispersions (no polysaccharide) and  MPC containing alginate formed large inhomogeneous aggregates. The lack of structural  homogeneity affected the simulated gastric emptying: there were marked differences in the type of aggregates present at various times of emptying depending on the hydrocolloid present in the mixture. MPC containing pectin or guar gum formed macroscopically homogeneous dispersion, with rather  small protein aggregates showing a large population of particles between 60 and 100 µm of diameter,  with marked differences in microstructure. Pectin created large coacervates, while guar microscopic  phase separated systems. These dispersions showed a higher extent of protein digestion, due to the  larger surface area created for enzyme activity compared to the macroscopically phase separated  matrices. In all cases, there was a large undigested fraction at the end point of 140 min. SDS PAGE

demonstrated differences in the casein peptides distribution depending on the type of polysaccharide  present during simulated gastric emptying. This in spite of similarities in cumulative protein emptied. It was concluded that in this semi-continuous in vitro gastric digestion model, structuring with polysaccharides has a significant impact on gastric emptying and protein digestion kinetics.

Keywords

Hydrocolloids, in vitro digestion, semi-dynamic, milk protein concentrate, food matrix