Short chain xylooligosaccharides: a potential prebiotic used to improve batter fermentation and its effect on the quality attributes of idli, a cereal–legume-based Indian traditional food

Xylooligosaccharides (XOS), a potential prebiotic exhibits important technological characteristics and
interesting nutritional properties. The major fraction in XOS produced enzymatically from corncob was
characterised as b-d-xylopyranosyl-(1,4)-d-xylanopyranose (xylobiose) using 13C and 2D-HSQC NMR. The
use of this XOS as a prebiotic in idli, a cereal ⁄ legume-based fermented cake, and its effect on texture,
fermentation and sensory characteristics was investigated. Idli batter was fermented with different
concentrations of XOS (0, 0.2, 0.4 and 0.6% w⁄ v) for 4–18 h conventionally. The addition of XOS
markedly increased lactic acid bacteria number (9.88 ± 0.08 log cfu g)1) which resulted in rapid reduction
in pH (4.61 ± 0.03) and specific gravity after 6 h of fermentation when compared to conventional batter
fermentation for 18 h without XOS (9.46 ± 0.06 log cfu g)1). Instrumental (colour and texture) and sensory
evaluation indicated that the optimum conditions were 0.4% XOS and 6 h fermentation. Idlis with XOS had
higher moisture content and a softer texture. Addition of XOS benefits both fermentation and idli quality.