Genotypic, grain morphological and locality variation in rice phytate content and phytase activity

H Lee,P Yiu,C Bong,S Loh,S Sarbini

doi:10.9755/ejfa.v26i10.18503

Abstract

Phytate complexes in whole grain rice are indigestible by human but can be broken down by endogenous phytase enzyme. The inherent phytate content and phytase activity could influence the nutritional quality of whole grain rice. This work aims to determine and identify their variability with genotypes, growing areas and grain morphology. It was found that the whole rice grain was largely high in phytate content (18.20 to 32.36 g/kg) but low in phytase activity (4.77 to 102.65 U/kg), with significant variation among cultivars. Phytate content was marginally different between growing locations but, with no significant difference among their genotypes and grain morphology. This variation could be due to locality factors such as cropping and fertilization practices in the cultivation site. Meanwhile, phytase activity appeared to be determined by genotype, grain width and grain length-to-width ratio. A relatively high phytase activity could be selected from the whole grain rice based on rounded grain and in the genotypic category of L. These types of rice cultivars could reduce the inherent phytate level and improve the nutritional quality of the whole grain rice.

Highlights

Whole grain diet is well recognized for counteracting the diet-related diseases and promoting good health (Shahidi, 2009)
Thirty Bario rice cultivars were collected in paddy form from seven locations (Figure 1) in Limbang, Miri and Bintulu division, Sarawak, Malaysia
The whole rice grain was generally high in phytate content but low in phytase activity

Summary

Introduction

Whole grain diet is well recognized for counteracting the diet-related diseases and promoting good health (Shahidi, 2009). Whole rice grain supplies calories but contains more vitamins, minerals and fiber than its processed equivalents (Champagne et al, 2004; Jones and Engleson, 2010). A wide range of phytochemicals in the rice bran serves as good source of biomedical components for consumers. They are often either beneficial or deleterious, depending on the dosage and their chemical compositions. Phytic acid (myo-inositol-1,2,3,4,5,6-hexakisdihydrogen-phosphate, IP6), is a strong chelating compound, naturally deposited in plant tissues as phytates in globoids Yiu Faculty of Agriculture and Food Sciences, Universiti Putra Malaysia, 97000 Bintulu, Sarawak, Malaysia

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