关键词: 大豆分离蛋白, 花青素, 漆酶条件, 碱性条件, 结构, 营养吸收

Abstract: In this paper we studied the covalent cross-linking mechanism of soy protein isolate (SPI) with different concentrations of anthocyanins in the presence of either laccase or alkali, and we also investigated the effect of this crosslinking on protein structure and absorption. The degree of cross-linking as well as the resulting conformational change of SPI was evaluated by three-dimensional fluorescence spectroscopy. The gastrointestinal digestion and nutritional absorption of anthocyanins-SPI conjugates were simulated using pepsin, pancreatin, and Caco-2 cells. And we also evaluated the degree of hydrolysis, antioxidant capacity, and the permeability of peptides during the digestion process. The results showed that the fluorescence intensity of SPI was reduced, and polypeptide chain unfolding and consequently tertiary structure changes occurred after cross-linking with anthocyanins. At the same time, the cross-linking increased the digestibility and antioxidant capacity of the protein and this effect was positively correlated with anthocyanin concentration, especially in the presence of laccase. It is worth noting that anthocyanins had an inhibitory effect on the permeability of peptides in a concentrationdependent fashion, which was stronger in the presence of laccase than in the presence of alkali at the same concentration of anthocyanins.

Key words: soybean protein isolates (SPI), anthocyanins, laccase, alkali, structure, nutritional absorption