New insight into bamboo shoot (Chimonobambusa quadrangularis) polysaccharides: Impact of extraction processes on its prebiotic activity

The in vitro digestibility, prebiotic activity, and physicochemical properties of polysaccharides obtained from bamboo shoots (Chimonobambusa quadrangularis) using different extraction processes were investigated in this study. Five polysaccharide fractions were prepared by hot water-, accelerated solvent-, ultrasound-, microwave-, and enzyme-based extraction processes. First, the chemical and monosaccharide compositions, molecular weights, zeta potentials, and particle sizes of the five fractions were assessed using colorimetry, high-performance liquid chromatography, high-performance gel permeation chromatography, and dynamic light scattering. Next, digestibility was tested using artificial gastric juice and α-amylase. Finally, the five polysaccharide fractions were added to liquid cultures of bifidobacteria and lactobacilli strains to serve as carbon sources alternative to glucose for in vitro fermentation to evaluate their ability to promote the growth of probiotic bacterial species and stimulate short chain fatty acids (SCFAs) production. It was found polysaccharides obtained by ultrasound- and enzyme-assisted extraction had significantly (p < 0.05) higher total carbohydrate contents of 61.9% and 61.5%, lower medium-high MWs of 117.49 and 117.25 kDa, and smaller particle sizes of 116.8 and 190.73 nm, respectively. All of the polysaccharide fractions were resistant to hydrolysis by artificial gastric juice and α-amylase. Furthermore, the five polysaccharides significantly stimulated the growth of the tested probiotics and increased lactic, acetate, propionate, and butyrate acids production from fermentation for 48 h compared to the control (p < 0.05). The polysaccharides prepared using ultrasound- and enzyme-assisted extraction processes displayed better prebiotic activity than the other fractions as they induced notably more proliferation of probiotic bacteria and higher production of SCFAs.