Physicochemical characteristics and retardation effects on in vitro starch digestibility of non-starch polysaccharides in jelly-fig (Ficus pumila L. var. awkeotsang)

The non-starch polysaccharides (NSPs) of two jelly-fig cultivars were extracted to compare their effects on the delay of glucose release and in vitro starch digestion with those of commercial agar. The ability of jelly-fig NSPs to retard glucose diffusion was investigated. The NSPs of both jelly-fig cultivars regulated glucose absorption. The Hongjiu cultivar had the highest rate of α-amylase inhibition (63.17 ± 0.04%). Jelly-fig NSPs reduced amylose leaching by 19–32%. The Hongjiu cultivar showed stronger cholesterol absorption ability compared with other NSPs. In vitro starch digestion indicated that jelly-fig NSPs were beneficial to the retardation of glucose release. The viscosity of jelly-fig NSPs was similar to those in in vitro starch digestion, indicating that the effects of jelly-fig on glucose release were strongly associated with viscosity. Scanning electron microscopy (SEM) indicated that jelly-fig NSP-treated starch granules were densely packed with smooth surfaces. The Hongjiu cultivar starch granules (34.93 μm) were substantially smaller than those of the control group (115 μm), indicating that starch granule gelatinization and swelling were attenuated. The NSPs of Hongjiu cultivar demonstrate potential in retarding glucose release in combination with starch sources to lower their glycemic index. This provides a novel natural source for blood glucose-controlling component in food products.