Physico-chemical investigations on varietal differences in rice. I. Sorption and desorption of water vapour by rice grains

Abstract

Dehydration of different varieties of rice has been studied employing for dehydration a current of hot air or vacuum desiccation over phosphorus pentoxide. Sorption and desorption of water vapour by rice under isothermal conditions has also been studied in a modified form of the quartz spring microbalance devised by McBain and Bakr. It is found that superior varieties of rice lose water more readily during dehydration and take up water at a faster rate and to a greater extent than varieties of poorer quality. Rice obtained from paddy that has aged is capable of easier hydration and dehydration than a sample of the same variety from freshly harvested paddy. The investigations indicate that the capillaries in superior varieties of rice are broader than those in inferior kinds. Storage of paddy seems to cause a widening of these capillaries.