Study on zinc accumulation, bioavailability, physicochemical and structural characteristics of brown rice combined with germination and zinc fortification

In this work, the combination treatment of zinc sulfate fortification and germination was used to increase zinc content and bioavailability of brown rice. The zinc content in brown rice during germination time of 10-34 h gradually increased with the increase of zinc sulfate concentration (0-100 mg/L). Brown rice with zinc fortified concentration of 25 mg/L and germinated for 28 h was recommended, which reached the maximum (26.31%) of zinc bioavailability and met the requirements of recommended dietary intake (RDA) of zinc. The physicochemical and structural characteristics of brown rice under different treatment conditions were compared. As the germination time prolonged, the germination rate (%), total phenol content, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging rate (%) and Gamma-aminobutyric acid content of fortified or unfortified brown rice increased, while the phytic acid content decreased. The fortification treatment improved total phenol content and antioxidant activity of germinated brown rice. The crystalline structure of brown rice was destroyed during germination, but no significant change of crystalline structure caused by zinc sulfate fortification was found. These results could provide valuable reference for the application of germination in the field of brown rice fortification and the preparation of zinc-rich germinated brown rice products.