Genotypic variation in milling depression of iron and zinc concentration in rice grain
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Background and aims
The loss of iron and zinc during milling to produce white rice can have serious consequences for human health. Therefore, the objective was to evaluate Fe and Zn partitioning between the endosperm, bran and embryo, and the milling loss of these nutrients among Thai rice genotypes.
Concentrations of iron and zinc and their partitioning to different parts of the grain were examined in 15 genotypes of Thai rice (10 belonging to the long-slender grain type) grown together under wetland condition.
The depression in grain Fe and Zn concentrations (24–60 and 10–58 %, respectively) on milling differed among rice genotypes and were affected by the extent of differential partitioning of Fe and Zn into different parts of the grain. For example, nearly 70 % of white rice Zn was allocated to the endosperm in contrast to only 43 % for Fe.
Because of variation in milling loss of Fe and Zn, that can result from genotypic variation in the degree of milling and partitioning of Fe and Zn into different parts of the grain, we conclude that white rice Fe and Zn concentrations should not be inferred solely from brown rice concentrations of these nutrients.
KeywordsBrown rice Degree of milling Long-slender grain type Milling loss White rice
The first author is a recipient of a Royal Golden Jubilee PhD scholarship. Support from Research University Project of Thailand’s Commission of Higher Education is also gratefully acknowledged. We thank Dr. Sittichai Lordkaew, Chiang Mai University for help with chemical analysis.
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