Effect of insect infestation on stored grain. II. Studies on husked, hand-pounded and milled raw rice, and parboiled milled rice

Abstract

Husked, hand-pounded, milled raw rice and parboiled milled rice obtained from the same strain of paddy (Halubbulu) were infested by Calandra (Sitophilus) oryzae (rice weevil) for a period of eight months and the changes brought about in the different samples due to infestation have been studied. The results show that husked rice was infested to a greater extent than the other samples and developed an unhealthy appearance within two months of infestation. Parboiled and raw, milled samples of rice were found to be least susceptible to infestation. Infestation of the rice grain increased the loss of starch in the gruel during cooking, the loss being maximum in the case of husked rice. An appreciable increase in the acidity of fat and a decrease in the thiamine content due to insect damage were observed. No significant difference was noted in the other constituents of the grain, such as total nitrogen and soluble nitrogen. Some correlation was observed between the weight/volume ratio of uncleaned grain and the proportion of dust, loss in total weight, loss in thiamine and insect population.