Protein/polysaccharide composite nanocoating based on amyloid-like aggregation for fresh-cut fruits preservation

Abstract

The increasing pace of modern life has led to the widespread popularity of fresh-cut fruits among consumers. However, their susceptibility to spoilage and short shelf life remains a significant challenge. Thus, there is an urgent need for simple, eco-friendly, low-cost, and energy-efficient preservation strategies. Herein, we report a novel method based on amyloid-like protein aggregation. Fresh-cut fruits are immersed in an aqueous solution containing lysozyme, L-cysteine, and pectin under ambient conditions, forming a ~ 12 nm thick, transparent, and colorless proteinaceous nanocoating embedded with pectin on the fruit surface. This nanocoating preserves the fruit's natural appearance and visual appeal while forming an ordered amyloid-like structure that strongly adheres to moist surfaces and offers excellent barrier properties. When applied to polyethylene (PE) film, the nanocoating reduces O₂, CO₂, and water vapor permeability of PE film by 48%, 62%, and 17%, respectively. In addition, the lysozyme-based coating provides effective protection against microbial contamination. Compared to untreated apples, coated samples exhibit a slower deterioration rate and an extended shelf life from 2 to 4 days at room temperature, as demonstrated by delayed weight loss, reduced firmness loss, and inhibited browning. Biochemical assays show minimal increases in malondialdehyde, polyphenol oxidase, and peroxidase levels during storage, indicating attenuation of oxidative and enzymatic degradation. Meanwhile, total soluble solids and vitamin C levels remain largely stable. In vitro cytotoxicity assays and mice feeding studies confirm the nanocoating's safety and edibility. This versatile, sustainable approach is broadly applicable to fresh-cut fruits and vegetables and offers a promising biomass-based solution to help reduce global food waste.