Zinc Accumulation and Distribution in Germinated Brown Rice

Abstract

Zinc (Zn) is an essential trace element for human health. Organic zinc (O-Zn) is more security and has higher bioavailability than inorganic Zn. Brown rice with embryo and can germinate under the appropriate condition. During germination, brown rice could absorb exogenous inorganic Zn and transformed it into O-Zn by combining with macromolecules. In this study, germination conditions for zinc accumulation in germinated brown rice were investigated and the zinc distribution in various parts and macromolecule fractions were analyzed. Germination time, temperature and Zn²⁺ concentration significantly affected O-Zn content and ratio of O-Zn to total zinc (T-Zn) (O-Zn/T-Zn). The optimized condition was germinating for 3 d at 30.28°C after 200 mg/L of Zn²⁺ soaking. Under the optimum conditions, the maximum O-Zn content (304.71 µg/g) and O-Zn/T-Zn (86.21%) were obtained. Moreover, 21.19% of O-Zn was found in the protein fraction, 30.42% in the polysaccharide fraction and 1.24% in the nucleic acid fraction. T-Zn, O-Zn content and O-Zn/T-Zn declined substantially from the outer layers to the inner endosperm of Zn-enriched brown rice. O-Zn mainly combined with polysaccharide compared with protein and nucleic acid.