Preparation and evaluation of arabinoxylan based prebiotics

Abstract: Prebiotics are non-digestible carbohydrates that selectively stimulate the growth and activity of health promoting bacteria in the colon, resulting in homeostasis to the gut environment. It is considered to be the solution of many health-related diseases such as type-2 diabetes, cardiovascular disease and cancer. Arabinoxylooligosaccharides, the hydrolysis product of arabinoxylan from plant cell walls, can be used as potential prebiotics as it is non-digestible to humans and can be fermented by the bacteria in the colon. Brewer’s spent grain, the residue from beer production, was used to extract arabinoxylan. The composition of brewer’s spent grain was analyzed and arabinoxylan content found to be 14.75% on a dry weight basis. Different pre-treatment methods were used to extract arabinoxylan-rich fractions from brewer’s spent grain. The best pre-treatment method was selected based on the purity of extracted arabinoxylan, simplicity of the process and possibility to use in large scale applications. The pre-treatment process simply consists of a heat-treatment step of the de-starched brewer’s spent grain and is followed by mild alkaline treatment. Xylanases were used to produce short-chain oligosaccharides from extracted arabinoxylan. Two pure xylanases namely RmXyn10A from GH family 10 and Pentopan Mono BG from GH family 11 were used to depict their product formation (hydrolysis) pattern. Meanwhile, seven other commercial xylanases were used to compare their efficiency in making short-chain oligosaccharides. Most of the commercial xylanases were found to be efficient in producing mono-saccharides (arabinose and xylose) while two pure xylanases were efficient in making short oligosaccharides. Well-established probiotic strain Lactobacillus brevis (DSMZ 1264) was used to perform growth studies by using arabinoxylooligosaccharides as carbon source. Analyzed results of samples after 48 hours of fermentation showed that oligosaccharides were utilized by Lactobacillus brevis.