Twin Function of Zein–Zinc Coordination Complex: Wheat Nutrient Enrichment and Nanoshield against Pathogenic Infection

Abstract

Cereal grains undergo a huge loss in storage, which is significantly due to microbial contamination; on the other hand, nutrient deficiency also coexists. Grain moisture is key for microbial contamination to occur; hence, we envisage coating the grain with edible hydrophobic moisture barrier “zein”. However, the challenge in coating zein is to have control over the zein film thickness. To date, there has been no report of a zein film thickness of less than 50 μm in a nonplanar surface. However, a coating thickness of less than 50 μm has appeared on a planar surface. In the present work, zinc is coordinated with the zein (Zinc@Zein), which unwraps the hydrophobic zein domain and also reduces the viscosity of non-Newtonian zein fluid to form a nanolayer coating. Zinc coordination furnishes an antimicrobial property as well as nutrient supplementation. The nanolayer of Zinc@Zein on Triticum aestivum provides efficient protection from seed-borne pathogen Pseudomonas syringae infection and increases available zinc by 4.5 times in a simulated gastric digestion and Caco 2 cell model study. Approximately ∼2–3 g of zein and 80 mg of zinc will be sufficient for coating 1 kg of grain to enhance mineral availability and antipathogenic effect.