Effects of storage temperature of whole rice grains with brown, black and red pericarps, on the physicochemical and pasting properties

Abstract

Rice (whole with brown, black and red pericarps, polished, whole parboiled and polished parboiled) is the staple diet in developing countries and serves as a vehicle for vitamins and minerals. Storage is an essential step, aiming to maintain the quality of the grains until they are industrialized and consumed, and storage temperature is one of the main factors causing changes during this period. Thus the objective of the present study was to evaluate the effects of storage time (6 months) and temperature (16, 24, 32 and 40 °C) of whole grain rice with brown, black and red pericarps on the proximate composition, the pasting properties, the soluble proteins, the pH values and the electrical conductivities of the grains. After six months storage there were increases in the pasting temperatures and electrical conductivities with reductions in the pH and protein solubility values, mainly for storage at 40 °C. The storage of rice grains with brown, black and red pericarps at 16 °C is the temperature most indicated for the reduction of their metabolic and enzymatic activities, providing the minimal changes in the physicochemical and pasting properties.

Keywords:
Pigmented rice; Conservation; Chemical reactions