Distribution of oil in the bran layers of slender, medium, and short grain varieties of rice, and effect of parboiling

Abstract

AbstractA study of the distribution of oil in slender (IR‐22), medium (Jaya), and short (Bala) grain types of rice indicated that the oil content of the bran was highest in IR‐22 (24.4%) followed by Jaya (22.8%) and Bala (15.2%) at a given (5%) polish percentage. Parboiling increased the oil yield of the bran in all the varieties, but much more in Jaya and Bala (7–9%) than in IR‐22 (3%) indicating that in the slender IR‐22, the oil was more concentrated in the surface layers of the grain. The oil content increased somewhat sharply in IR‐22 and Bala up to 4.0 and 5.5% polish, respectively, and then declined with further polish. In Jaya, the increase was smaller and more or less constant up to 6.0% polish. Changes due to parboiling were similar to those for raw samples with higher values for the parboiled samples. Distribution in surface fractions showed highest values for each fraction from the slender IR‐22 followed by the medium Jaya and the short grain Bala. The pattern of distribution was, however, strikingly different in the slender variety compared to the others. Difference between raw and parboiled fractions in each variety was not similar: in IR‐22, the increase in parboiled samples was 5–7%, 5–13% in Jaya, and as much as 1–11% in Bala.