Distribution of pentosans in barley pearling flour fractions

Pentosans contribute to the cell wall structure in wheat, rye and barley. These dietary fibre components were extracted from Candle pearling flour in four sets: (i) different initial alkali concentrations (0.04M-0.2M NaOH) at 55°C [pH 9 and 11]; (ii) water or alkali (O.1M NaOH) extraction at different temperatures (23, 55 and 90°C) and pH (6 and 11); (iii) use of alpha-amylase, fungal protease or ultrasound treatment at 55°C and pH 5.5; (iv) water or 0.0375M NaOH at 55°C, pH 5.5 and 11, and enzyme-ultrasound combination treatment. Soluble and insoluble fractions obtained were quantified, examined with scanning electron microscopy and analyzed for composition, yield and recoveries. The majority of pentosans was not solubilized and ended up in the insoluble fraction, except for the high alkali conditions. Samples treated with ultrasound presented higher pentosan content with better disruption of the bran tissues. These findings contribute to the value-added processing initiatives for barley.