For the laboratory analyses, the grains were processed in different
ways as follows:
brown,
polished,
parboiled brown
and parboiled
polished.
The grains were evaluated both raw and cooked. To obtain the brown grains, grains were dehulled, and the absence of lines in the grains was observed, indicating that no bran was lost during processing.
To obtain the polished grains, the dehulled grains were polished to remove the external layers of the grain (bran). Rice was parboiled according to the adapted methodology of Elias, Rombaldi, Silva, Nora, and Dias (1996). The grains with the hull were soaked (grain mass:water volume ratio 1:1.5) in heated water at 65 °C ±2 °C for 300 min and autoclaved at 116 °C±1 °C (pressure 0.6 kPa± 0.05 kPa) for 10 min. After this treatment, the samples were dried to 13%±1% moisture at a grain mass temperature below 40 °C.
To obtain the parboiled brown rice, the grains were dehulled, and to obtain the parboiled polished rice, grains were dehulled and polished. To evaluate the cooked rice, the grains were cooked in a grain mass: water volume ratio of 1:2.5 for 30 min and then dried at 50 °C. The grains were ground to obtain the right particle size for the analyses.