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

The micronutrient deficiency affects more than two million individuals, there for it is a public
health problem that can lead to various diseases, so we should pay more attention to it
nowadays. In order to combat this problem, several alternatives have appeared, namely
biofortification, which consists on increasing the amount of nutrients in food crops. Zinc is one of
the most relevant micronutrients for the body and has three main roles: catalytic, structural and
regulatory. The deficiency of this micronutrient leads to several health issues. In order to put zinc
biofortification into practice, a technical itinerary was outlined which took place in the fields
located in Palmela (Portugal). This work aims to optimize a response to zinc biofortification of
two grape varieties Fernão Pires and Syrah. Biofortification was performed with leaf applications
of zinc oxide (ZnO) and zinc sulfate (ZnSO4) throughout the production cycle. In order to assess
the efficiency of biofortification, atomic absorption spectrophotometry and μ-EDXRF M4
TornadoTM were used in this process. Both techniques demonstrated an increase in zinc content.
Considering both grape varieties measured by atomic absorption spectrophotometry, there was
an increase of 1.2 times and 2.2 times for Fernão Pires and Syrah respectively. Through tissue
analysis, Fernão Pires and Syrah showed a substantial rise in zinc levels in the grape’s skin, with
the application of zinc oxide or zinc sulfate.