Roller milling fractionation of green gram (Vigna radiata): optimization of milling conditions and chemical characterization of millstreams.

Abstract

In the view of recent growing interest in utilization of grain fractions as food ingredient, present investigation was carried out to evaluate the roller milling potential of green gram. The effect of conditioning moistures on green gram roller milling were studied. The results showed decrease in flour yield from 85.56 to 58.74% with increase in conditioning moisture from 10 to 16%. Higher yield of flour was observed from the first (C1), second (C2) and third (C3) reduction passages; whereas, the first (B1), second (B2) and third (B3) break passages produced less flour. The distribution of protein, dietary fiber, ash and fat in different flour streams and by-products from roller milled fractions of green gram showed wide variation. The protein content increased with increasing numbers of breaks and reductions in the flour streams. The highest protein content of 30.16% was found in bran duster flour and lowest (11.32%) in fine seed coat. The protein content of break streams was found lower than reduction streams. The dietary fiber content of coarse seed coat was highest (71.17%) followed by the fine seed coat (57.22%). The microstructure studies of milled fractions of green gram showed more deformed and damaged starch granules in reduction flour streams than break flour streams.