Influences of different drying methods on the structural characteristics and prebiotic activity of polysaccharides from bamboo shoot (Chimonobambusa quadrangularis) residues

In the present study, in order to assess the influences of drying methods on the chemical structures, in vitro digestibility and prebiotic potential of polysaccharides extracted from Chimonobambusa quadrangularis shoot (CPSs), four drying methods, including hot air-, vacuum-, freeze-, and spray-drying, were utilized to dry CPSs. Results revealed that the physicochemical characteristics and prebiotic activity of CPSs varied by different drying methods. In comparison with the other drying methods, freeze-dried CPSs had higher uronic acid content (9.58%), lower medium-high molecular weight (117.63 kDa), smaller particle size (115.97 nm) and better solubility. All four CPSs fractions exhibited low degree of digestibility to pretended human gastric juice (< 2%) and α-amylase (< 5%). The freeze-dried CPSs showed the greatest prebiotic activity as this polysaccharide induced the strongest proliferation effect of probiotic bacteria and the highest production of total short chain fatty acids. Our results collectively provided substantial evidence that the freeze-drying method proposed in this study could be an effective technique in improving the prebiotic potentiality of CPSs.