Effect of rice storage on pasting properties of rice flour

The pasting properties of rice flour following storage of the grain for up to 16 months were investigated. Storage produced changes in the RVA pasting curves of the flour as a varietal, time and temperature dependent phenomenon. The data confirm that viscograms from samples stored at 4 and 37 °C provide a valid comparison of the effects of ageing on pasting behaviour. The most significant change in the pasting curve was the decrease in BD over time and the gradual disappearance of a clearly defined peak in aged samples. Chemical (β-mercaptoethanol) and enzyme treatments (hemicellulase, cellulase and protease) of flour obtained from aged rice produced various changes in the RVA viscograms. The most notable effect was produced by protease treatment which increased PV and decreased FV of flours from aged (higher temperature storage) rice samples. Aged samples treated in this way showed a peak and trough as normally seen in fresh rice. Thus, protein appears as a key component in the ageing process.