Evaluation of Superabsorbent Capacity of Soy Protein-Based Bioplastic Matrices with Incorporated Fertilizer for Crops

Recent studies proposed the use of soy protein-based bioplastic matrices with incorporated micronutrient to mitigate against the excessive use of fertilizers in horticulture. However, the micronutrient incorporation reduced the superabsorbent capacity of these bioplastic matrices. All this reduces their use as a source of water for crops in times of drought, among other possibilities. The objective of this study was to evaluate different alternatives in order to incorporate the desired micronutrient (Zn) in soy protein-based bioplastics without losing the superabsorbent capacity of the latter. For this, three salts were used: zinc sulphate monohydrate (ZnSO4 center dot H2O), zinc chloride (ZnCl2) and zinc chelated with 2,2 ',2 '',2 '''-(Ethene-1,2-diydinitrilo)tetraacetic acid (Zn-EDTA). Considering the possible factors that can affect the absorption of these bioplastic matrices, modifications were made in their pH, ionic strength and complex character of the salt. Thus, the amount of load micronutrient, mechanical and morphological properties, as well as water uptake capacity of the bioplastic matrices with different salts incorporated were evaluated. The results of this study helped to understand the effects of the loss of the superabsorbent capacity of soy protein-based bioplastic matrices with incorporated zinc.