Biodeterioration in Rice (Oryza sativa L.) due to low, medium and high moisture

The changes in moisture content, microflora, biochemical constituents and dry matter were assessed in ADT 31 and TKM 9 paddy (Rice: Oryza sativa L.) grains with low, medium and high moisture content stored for 90 days without drying, just after harvest in rainy humid weather. The drop in moisture was conspicuous only after 15 days of storage. The fungal flora increased rapidly at all moisture levels within a week with a two-to-fourfold increase in low and medium moisture and almost sixfold in high moisture paddy. There was also an increase in the bacterial flora in grains at high moisture levels. In both the varieties of paddy, the sugars increased upon storage and this was relatively higher with increased moisture levels. On the other hand, reducing sugars decreased upon storage and the decrease was greater in high moisture lots. The amylase activity showed a general increase in all moisture lots. An increase in amino acids was observed at all moisture levels up to 15 days after which values fluctuated depending upon the moisture content. The phenolic compounds in paddy decreased upon storage at all moisture levels. The biodeterioration resulted in a dry matter loss of 2·09, 2·99 and 7·67% in ADT 31 and 1·96 and 5·88% in TKM 9 paddy after 90 days respectively in low, medium and high moisture paddy. This also resulted in a decreased in the outturn of milled rice after raw or parboiled milling.