Variety difference in physico-chemical, cooking, textural, pasting and phytochemical properties of pigmented rice

Abstract

Three different varieties of pigmented rice namely Chakhao Amuba (Black), Chakhao Angangba (Red), Chakhao Poreiton (Purple) and a non-pigmented Chakhao Angouba (White) rice grown in Manipur, India were investigated for their physicochemical, phytochemical, cooking, textural and pasting properties. Thousands kernel weight, bulk density and length/breadth ratio for all varieties varied in the range of 16.69 to 21.17g, 0.59 to 0.65g/mL and 2.87 to 3.25, respectively. All pigmented rice showed significant amount of total phenolic content, flavonoid content and antioxidant activities. Black rice showed the highest phenolic content (12.70 mg GAE/g), Red rice showed highest flavonoid content (6.12 mg catechin/g) and DPPH % inhibition (92.62 %). Highest anthocyanin content was observed in the black rice variety (9.13 mg Cyanidin-3-glucoside/g). Cooking time was found highest (31.33 min) in Purple rice which can be correlated with the amylose content. Maximum amylose content was recorded in purple rice (6.44g/100g). Water uptake ratio was found in the range of 2.03 to 2.71. Highest amylose content rice (Purple rice) has the highest hardness value (173.18 N) which is positively correlated with the amylose content. The colour values were reduced after cooking of rice which may be due to degradation in monomeric anthocyanins due to heat treatment. Red rice showed the highest pasting temperature, peak, hold and final viscosity compared to other rice varieties.