Studies on pentosans in Indian wheat (Triticum aestivum) varieties in relation to chapati making quality

Different wheat varieties were screened for chapati making characteristics, of which DWR-162 and GW-322 showed good and MACS-2496 and HD-2189 exhibited poor chapati making quality. Various polysaccharide fractions such as water-soluble, barium hydroxide-soluble and alkali-soluble polysaccharides (viz., hemicelluloses A and B) were isolated from these wheat varieties and their carbohydrate composition was analysed by gas liquid chromatography. Glucose was the major sugar, along with small amounts of arabinose and xylose in water-soluble fractions. Barium hydroxide extract mainly consisted of arabinose and xylose, along with small amounts of glucose. Hemicellulose A fractions contained mainly xylose. Arabinose, xylose and glucose were the major sugars observed in hemicellulose B fractions. Hence, hemicellulose A may be more xylan type, while, hemicellulose B appears to be of complex hemicellulosic nature. Alkali-insoluble residue was basically cellulosic in nature and was strongly associated with arabinoxylans. The studies indicated that arabinose to xylose (A/X) ratio was higher in varieties having good chapati making quality compared to poor varieties in the flour and barium hydroxide extract, which are rich in arabinoxylan type polysaccharides. The ratio of xylose to glucose (X/G) was higher in good chapati making varieties compared to poor varieties.