Grape Enrichment with Zinc for Vinification: Mineral Analysis with Atomic Absorption Spectrophotometry, XRF and Tissue Analysis

Micronutrient deficiency affects individuals all around the world, being a public health problem. To minimize this problem, several alternatives are being developed, namely agronomic biofortification, to increase the amount of nutrients in food crops. In this context, Zn is one of the most relevant micronutrients for the human body, displaying catalytic, structural, and regulatory properties. Considering that Zn deficiency leads to health disorders (namely, neurological disorders, autoimmune and degenerative diseases related to age, Wilson’s disease, cardiovascular problems, and diabetes mellitus), a technical itinerary for biofortification was outlined in a field of grapes located in Palmela (Portugal), aiming to optimize Zn content for the Syrah variety. Biofortification was performed with foliar spraying of zinc oxide (ZnO) and zinc sulfate (ZnSO4) throughout the production cycle (at concentrations of 0%, 30%, and 60%—0, 450, and 900 g ha−1). The zinc biofortification index increased about 59% and 45%, respectively, with OZn60 and SZn60 (i.e., concentrations of 60% with treatment ZnO and ZnSO4 respectively), whereas its deposition in the flesh of the grapes increased 2.41- and 2.37-fold and in the seeds by approx. 1.76- and 2.19-fold (with OZn60 and SZn60, respectively). After vinification, significant increases in Zn content in the wine were also found (1.92- and 1.77-fold); however, considering the amount of this nutrient in grapes, it was concluded that vinification must also be optimized.