Development of soy protein-based matrices containing zinc as micronutrient for horticulture

Abstract

Protein-based bioplastics may be regarded as novel biopolymer matrices based on renewable natural components. Due to technological, economic and environmental benefits, these biopolymer matrices are highly attractive for the incorporation and subsequent release of micronutrients that are essential for the development and health of plants, avoiding the typical excesses of conventional fertilizers. In addition, soy protein isolate (SPI) seems to be an adequate resource for the manufacture of natural-based superabsorbent materials due to its hydrophilic character and excellent processability when combined with a plasticizer. The objective of this work is to develop soy protein-based bioplastic matrices loaded zinc sulphate monohydrate with potential applications in horticulture. With this aim, the micronutrient loading level and water absorption are the most important properties to assess. The effect of the presence of a selected micronutrient (zinc) at different concentrations in the soy protein-based matrix was assessed, evaluating the mechanical properties, water uptake capacity, microstructure and loading level of zinc. The results confirm that important amounts of an essential micronutrient for a plant (Zn) can be incorporated into bioplastic matrices, modifying water absorption, mechanical and microstructural properties. In any case, the results obtained in this work open up a great potential for the use of this matrices as a supplying source of micronutrients for horticultural crop applications.