Effect of in vitro gastric digestion conditions on physicochemical properties of raw apple fruit cell wall polysaccharides

Properties of cell wall polysaccharides of raw nectarine fruits after treatment under conditions that modulate gastric digestion

The results of the study of the physicochemical properties of the high-molecular-weight soluble and insoluble components of nectarine cell walls obtained by fruit treatment under conditions that modulate of gastric digestion are presented. Homogenized nectarine fruits were sequentially treated by natural saliva and simulated gastric fluid (SGF) at pH 1.8 and 3.0. The isolated polysaccharides were compared with polysaccharides obtained by sequential extraction of nectarine fruit with cold, hot, and acidified water, solutions of ammonium oxalate and sodium carbonate. As a result, high-molecular-weight water-soluble pectic polysaccharides, weakly bound in the cell wall, were dissolved in the simulated gastric fluid, regardless of pH. Homogalacturonan (HG) and rhamnogalacturonan-I (RG-I) were identified in all pectins. It was shown that their quantity and ability to form highly viscous solutions determine high values of the rheological characteristics of the nectarine mixture formed under simulated gastric conditions. The modifications occurring with the insoluble components under the influence of acidity of SGF were importance. They determined difference in the physicochemical properties of both the insoluble fibres and the nectarine mixtures.

In vitro simulated digestion affecting physicochemical characteristics and bioactivities of polysaccharides from barley (Hordeum vulgare L.) grasses at different growth stages

In this study, three polysaccharides (BGPs: BGPs-Z21, BGPs-Z23, and BGPs-Z31) were successively extracted from barley (Hordeum vulgare L.) grasses (BG) at different growth stages, including seedling (Z21), tillering (Z23), and stem elongation (Z31). The effects of in vitro simulated saliva-gastrointestinal digestion on the physicochemical characteristics and biological activities of BGPs were investigated and compared. Results showed that the simulated saliva-gastrointestinal digestion had considerable influences on reducing sugar content, chemical components, monosaccharide constituents, and molecular weights of BGPs but hardly affected their preliminarily structural characteristics. Moreover, the antioxidant activities of BGPs were weakened after the simulated saliva-gastrointestinal digestion, but their bile acid-binding capacities were remarkably enhanced. The digested BGPs-Z31 by gastric juice possessed better antioxidant benefit, and bile acid-binding capacity (80.33 %) than other digested products. Overall, these results indicated that BGPs obtained from BG are valuable for functional foods as promising bioactive ingredients.