Influence of variety, storage, and simulated gastrointestinal digestion on chemical composition and bioactivity of polysaccharides from sweet cherry and apple tree fruits

This work examined the effect of extraction regime (hot water vs. simulated in vitro gastrointestinal digestion) and postharvest storage on the chemical composition, molecular weight, and bioactive properties of polysaccharides obtained from sweet cherries (Lapins and Staccato varieties) and apples (Gala and Fuji varieties). The yields of the polysaccharides isolated from cherries and apples ranged from 0.2 to 2.4% on a dry weight fruit basis. All of the isolated polysaccharides contained protein, phenolic compounds, and uronic acid. All polysaccharides contained the sugar monomers: rhamnose, arabinose, xylose, mannose, galactose, and glucose. Also, all of the polysaccharides obtained using the different extraction regimes were shown to possess antioxidant activity as determined with the ferric reducing antioxidant power and the 2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assays. Only the polysaccharides isolated from the cherry and apples after simulated in vitro gastrointestinal digestion showed appreciable α-glucosidase inhibition activity, with polysaccharides obtained from Staccato cherries showing nearly 90% of the inhibition of α-glucosidase as achieved with the positive control acarbose. This work shows that bioactive polysaccharides are available and/or can be isolated during digestion which supports the concept that fruit polysaccharides play a role in enhancing human health.