Indian Journal of Experimental Biology Vol. 53, March 2015, pp. 131-142 Minireview Xylooligosaccharides: an economical prebiotic from agroresidues and their health benefits Ira Jain, Vikash Kumar & T Satyanarayana* Department of Microbiology, University of Delhi, South Campus, Benito Juarez Road, New Delhi-110 021, India Received 23 January 2014; revised 09 June 2014 Oligosaccharides and dietary fibres are non-digestible food ingredients that preferentially stimulate the growth of prebiotic Bifidobacterium and other lactic acid bacteria in the gastro-intestinal tract. Xylooligosaccharides (XOS) provide a plethora of health benefits and can be incorporated into several functional foods. In the recent times, there has been an over emphasis on the microbial conversion of agroresidues into various value added products. Xylan, the major hemicellulosic component of lignocellulosic materials (LCMs), represents an important structural component of plant biomass in agricultural residues and could be a potent bioresource for XOS. On an industrial scale, XOS can be produced by chemical, enzymatic or chemo- enzymatic hydrolysis of LCMs. Chemical methods generate XOS with a broad degree of polymerization (DP), while enzymatic processes will be beneficial for the manufacture of food grade and pharmaceutically important XOS. Xylooligomers exert several health benefits, and therefore, have been considered to provide relief from several ailments. This review provides a brief on production, purification and structural characterization of XOS and their health benefits. Keywords: Dietary fibres, Lignocellulosic materials (LCMs), non-digestible sugars (NDOs), Oligosaccharides, XOS, Xylan, Xylanases, Xylooligomers The prebiotics are non-digestible food ingredients that beneficially affect the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon and thus improve the host’s health 1 . The beneficial bacteria ferment the prebiotic oligomers that results in the acidification of the colon and formation of short chain fatty acids which serve as fuel in different tissues and may play a role in the regulation of cellular processes 2 . The useful properties of prebiotics include maintenance of intestinal flora and stimulation of intestinal transit 3 , change in colonic microflora contributing to normal stool consistency leading to prevention of diarrhea and constipation 4,5 , reduction in the level of triglyceride content of blood and liver 6 , stimulation of growth of Bifidobacterium 7 and improved nutrient absorption and production of B complex vitamins 8 . All the health benefits collectively lead to improvement in the immune system 9 . The overall mechanism of action of prebiotics is illustrated in Fig. 1. The oligosaccharides with low degree of polymerization (2-20 monomers) are considered as potential non-digestible sugars (NDOs) known for their benefits as dietary fibres. Although these are in use as dietary supplements since antiquity, they have seldom received due attention compared to other carbohydrates such as simple sugars and other edible polymers. Recently, the significance of NDOs has been realized mainly due to their properties like sweetening ability, water binding capacity, fat replacement value and notably their resistance to digestion in the upper tract of the gastro-intestinal tract and fermentation in the large bowel. The non-digestible oligosaccharides can be incorporated into processed foods and could be promising functional ingredients in neutraceutical products 10 . Their utility is not limited to their potential neutraceutical properties, but also for their economic benefits as they provide an opportunity for agro-food industries to produce value added products from wastes and thereby improve the environment through agro-food waste management. The waste generated from agro- industries mainly consists of plant biomass that can be converted into NDOs using suitable microbial enzymes. In the bioconversion of lignocellulosic biomass, production of cellulosic ethanol is the main focus of research due to its abundance, low cost and small carbon footprint 11 . However, a facility solely  *Correspondence: Ph. +91-11-24112008; Fax: +91-11-24115270 E-mail: tsnarayana@gmail.com