Zinc concentration and bioavailability of Chinese steamed bread prepared from foliar zinc-biofortified wheat grain

BACKGROUNDIncreasing the concentration of zinc (Zn) in a widely consumed staple food, such as Chinese steamed bread (CSB), is a promising strategy for alleviating Zn malnutrition in humans. The aim of this study, which was based on a 2-year field experiment, was to evaluate the effectiveness of spraying Zn fertilizer combined with commonly applied (i) pesticides and/or (ii) KH2PO4 (PK) to increase the concentration of Zn and its bioavailability in wheat grain and the CSB derived from it. RESULTSAll the foliar Zn applications (foliar Zn alone or combined with pesticides and PK) significantly increased the concentration of Zn in grain and derived CSB by 69.1% and 63.1%, respectively. Milling caused an 86-88% loss of Zn, while the process of producing CSB caused an 11-26% increase in the concentration of Zn. A net gain of 2.5-8.3 mg Zn kg(-1) of CSB was achieved owing to foliar applications of Zn. The concentration of phytic acid (PA) decreased dramatically during milling (89-90%) and the production of CSB (69-72%). As a result, the Zn bioavailability was greater in the CSB than in grain. Foliar applications of Zn also increased the estimated Zn bioavailability of CSB to be as high as 5.5-7.8 mg, which is adequate for human nutrition. Enrichment with Zn had no adverse effects on the quality of CSB. CONCLUSIONThe mixture of foliar Zn with pesticides and PK represents a useful approach to improve the bioavailable Zn of CSB without altering its quality. (c) 2023 Society of Chemical Industry.