Effect of Hemicellulose on Viscosity of Rice Flour

Effects of water-soluble bran and endosperm hemicelluloses on Brabender viscosity curves of intact and hemicellulose-free rice flour were examined over the complete cooking and cooling curves. Amylograph curves of long- and medium-grain rice flour with added bran hemicellulose showed no difference; both had lowered viscosity. Similarly, addition of a ferulic acid-containing polysaccharide isolated from bran hemicellulose to the intact rice flour also lowered viscosity. This complex polysaccharide may, therefore, be responsible for at least part of the viscosity reduction upon addition of the bran hemicellulose. Amylograph curves of long- and medium-grain rices were different when endosperm hemicellulose was added back to the intact flour. When hemicelluloses were completely removed and increasing amounts added back, changes in viscosity correlated with the amounts of added hemicellulose.