Amylose-lipid complex formation during cooking of rice flour

The effects of cooking rice flour in the presence of myristic, palmitic and stearic acid on amylose-lipid complex formation, water solubility and past ing properties were studied. Different fatty acids were added to rice flour , at 1.5, 3.0 and 4.5% levels, and cooked in Visco-amylograph at 95 degrees C for 30, 60 and 90 min. Amylose-lipid complex formation increased and wat er-solubility decreased with the increase-in levels of all the fatty acids in rice paste cooked for 30-90 min. Complexing of amylose with all the fatt y acids increased with the increase in cooking time. Myristic acid had the highest ability to form the complex and stearic acid the lowest. Iodine spe ctra of rice paste cooked with and without lipids were also determined to c onfirm the formation of amylose-lipid complexes. Both lambda(max) and ratio s of absorbances at 630 and 520 nm decreased with the increase in levels of all the fatty acids. Myristic acid caused a greater reduction in lambda(ma x) and ratios of absorbance. Addition of all the fatty acids increased the pasting temperature, peak viscosity, viscosity at 95 degrees C and viscosit y at 50 degrees C of rice paste. Consistency coefficient and flow behaviour indices of rice pastes cooked in the presence of different fatty acids wer e also determined using a Brookfield viscometer. Consistency coefficient in creased with the increase in levels of all the fatty acids and the increase was more pronounced with myristic acid. (C) 2000 Elsevier Science Ltd. All rights reserved.