Effect of methods of analysis and heat treatment on viscosity of wheat, barley and oats

The purpose of this work was to study variation in viscosity of different g rain samples using different extraction methods, and to study effect of hea t treatment on viscosity. A total of 80 samples of wheat, oats and barley h arvested at two locations were analysed for physical appearance, fibre cont ent, and in vitro viscosity using water (WEV), acidic buffer (AEV), HCl/NaH CO3 buffer with pepsin and pancreatin added (IDV) or the Avicheck(TM) metho d (FFV). A transformation where the natural logarithm of the relative visco sity value was divided by the concentration of the sample in liquid was sho wn to give stable values over a wide range of sample concentrations in liqu id for WEV and IDV. Barley and oars had similar viscosities although there was considerable variation between samples, while viscosity was much lower and with less variation between samples for wheat. Heat treatment in an aut oclave at 100 degreesC for 5 min increased WEV fur all samples, but IDV inc reased for oats only as a consequence of heat treatment. Although WEV was m uch lower than IDV, the correlation between these two viscosities was high (0.95, P < 0.05) for barley and moderate (0.68 and 0.69, P < 0.05) for whea t and oats. A moderate to high significant correlation existed between visc osity and soluble fibre content for barley. (C) 2000 Elsevier Science B.V. All rights reserved.