EFFECTS OF FERMENTATION ON PHYTATE PHOSPHORUS AND MINERAL CONTENT IN BLACK GRAM, RICE, AND BLACK GRAM AND RICE BLENDS

Abstract

ABSTRACTQuantitative changes in phosphorus compounds and mineral content of black gram, rice, and black gram and rice blends were investigated during fermentation. Black gram cotyledons and polished Texas long‐grain rice had phytate phosphorus content of about 4.80 and 0.97 mg/g, respectively, on a dry weight basis. Phytate phosphorus accounted for about 51% of total phosphorus in rice. Fermentation of rice alone for 8 hr resulted in complete hydrolysis of phytate phosphorus with simultaneous increase in the quantities of nonphytate phosphorus. At 45 hr fermentation, about 13.33% and 48.80% of phytate phosphorus was hydrolyzed in black gram and black gram and rice blends, respectively, with subsequent increases in non‐phytate phosphorus. No apparent changes were observed in the concentrations of calcium, magnesium, zinc, and iron; the inorganic sulfur content was decreased in black gram, rice, and black gram and rice blends as the fermentation progressed to 45 hr. The 20‐hr fermented black gram and rice batter was judged to produce an optimum quality of steamed product (Idli) which contained about 1.51 mg/g of phytate phosphorus. Scanning electron microscopy was employed to study the physical changes in the black gram and rice fermented batters and Idli. The Idli had a fine net work (spongy) type of texture and did not contain the starch granules compared to corresponding unsteamed samples.