RICE PROTEIN AGGREGATION DURING THE FLAKING PROCESS

The effect of roasting of soaked paddy rice and its subsequent flaking during production of rice flakes on solubility of rice proteins in va rious solvents was investigated. The solvents were so chosen to provid e an understanding of the type of protein-protein interactions occurri ng during processing. There was an increase in protein solubility upon roasting of soaked paddy in fine hot sand (175-250 degrees C) - a pre lude to the flaking process - however, after subsequent flaking solubi lity decreased. Gel filtration studies indicated that aggregates with molecular weights greater than 4x10(7) kDa formed during flaking as a result of disulphide bonding. The aggregates were composed of 68, 31-3 4 and 24 kDa proteins. Of these, the 31-34 kDa proteins were identifie d as 'putative prolamins'. These proteins require detergent for their initial solubilisation. The prolamins of 13-16 kDa were not involved i n the formation of aggregates. Their solubility decreased after flakin g. The higher molecular weight proteins involved in aggregate formatio n were susceptible to proteolysis, whereas the 13 kDa prolamin was res istant. (C) 1998 Academic Press.