Assessment of the prebiotic potential of oligosaccharide mixtures from rice bran and cassava pulp

Hydrothermal treatments (135 °C, 0.22 MPa, 0.5-3 h) of two kinds of agricultural wastes, rice bran and cassava pulp, resulted in hemicellulosic oligosaccharide mixtures. Acidic hydrolyses of these oligosaccharide mixtures revealed that they were mostly composed of glucose, galactose and mannose. Microbial utilizations of the obtained oligosaccharide mixtures showed that they were able to promote the growth of two from three Lactobacillus, as well as three from five Bifidobacterium species tested. Neither of rice bran nor cassava pulp derived oligosaccharide mixtures promoted the growth of Eubacterium cylindroides and Clostridium scindens. From the three tested Bacteriodes strains one utilized the cassava pulp oligosaccharide mixture better than inulin, while two grew better on rice bran oligosaccharide mixture than on inulin. Furthermore, the two oligosaccharide mixtures were found to be stable at 85 °C for 30 min. Similarly, these mixtures were able to withstand their exposure to simulated human gastric juice (pH 1-5) and to pancreatin treatments for up to two hours. To the best of our knowledge this is the first report that describes bifidogenic effects of rice bran and cassava pulp oligosaccharides extracted by hydrothermal treatment.