The injection of zinc sulfate into banana tree pseudostem can triple the zinc content and it is an effective method for fruit biofortification

Abstract

The diets of populations in developing countries are mainly composed of plant-based foods, which are low in micronutrients and may lead to the incidence of nutritional deficiencies. The deficiency of zinc (Zn), among other nutrients, has been associated with growth deficit in children, especially when the Recommended Dietary Allowance (RDA) of Zn is not achieved. In these countries, bananas and plantains are considered staple foods of massive consumption, but with low Zn content. Therefore, the objective of this study was to verify the feasibility of the fortification and biofortification of banana fruit aiming to reach the RDA of Zn for children at the age of 1–3 years (3.0 mg day−1) and to verify the effect of these treatments on the postharvest shelf-life and fruit quality. Banana fruit fortification by immersion was not effective due to the low infiltration of the acid blue 9 dye, used to predict the infiltration of zinc sulfate solutions (ZnSO4*7 H2O). On the other hand, it was possible to biofortify the banana fruit by means of the injection of zinc sulfate solutions into the pseudostem, tripling the Zn content in the fruits compared to the control. The consumption of 81.9 or 88.5 g of dehydrated bananas from the treatments that received 20 and 40 g L−1 of zinc sulfate, respectively, supplies 100 % of RDA of Zn for children at the age of 1–3 years. Likewise, the consumption of three biofortified fresh bananas per day from these treatments would supply this RDA. The postharvest shelf-life of zinc sulfate biofortified bananas was not affected by these treatments, but it was observed a decrease in the organic acids content and an increase in ratio, which might improve the acceptability of biofortified fruits, without compromising its nutritional potential.