Influence of Zinc Fertilization for Physical and Chemical Parameters and Sensory Properties of Grapes

As nowadays there is a growing concern about micronutrients deficiency in human food products, agronomic biofortification is being considered an enrichment potential technological option. In this context, to surpass limitations of Zn intake, ensuring proper level of this element for growth and maintenance of human health, this study aimed to develop a technological workflow for Zn enrichment of grapes (Syrah variety of Vitis vinifera) and assess the related quality. A foliar application of zinc oxide (ZnO) or zinc sulfate (ZnSO₄) (respectively, at a concentration of 30% and 60% - 450g ha⁻¹ and 900g ha⁻¹) was carried out. At harvest, Zn enrichment in grapes revealed a 1.6 fold increase relatively to control. In Zn biofortified grapes, the analysis of the color parameters, through the Cielab system, a low luminosity, low contribution of green and greater input of blue (as indicated by L, a and b parameters) was found. Concerning to firmness, penetration force and hardness of the pulp, no significant differences were found between the control and treated samples, which additionally pointed that fruit texture was not affected. Sensory analysis of the grapes further pointed a positive response to biofortified grapes. It was concluded that biofortification of grapes can mitigate the deficiency of zinc without negative effects on quality.