Starch and Shellac Polymer Blends: A Promising Material for Extending Postharvest Fruit Shelf Life

Abstract

This study optimizes edible coatings made from starch and shellac (SHL) polymer blends to enhance postharvest preservation of fruits. Various starch:SHL ratios are explored for the following four different starch sources: rice (RIC), corn (COR), glutinous rice (GLU), and tapioca (TAP). The resulting polymer blend films are comprehensively analyzed via X‐ray diffraction, Fourier‐transform infrared spectroscopy, contact angle measurements, and studies of swelling behavior, water solubility, water vapor permeability, and mechanical properties. Phase separation is noted in the RIC:SHL and COR:SHL polymer blend films, while the TAP:SHL and GLU:SHL polymer blend films exhibit homogeneity without discernible interactions between starch and SHL. However, the TAP:SHL blend films exhibit superior mechanical properties compared with the GLU:SHL polymer blend films. Furthermore, the wettability, swelling, and water vapor permeability decrease upon increasing the SHL content in the polymer blend films. Noteworthily, the TAP:SHL polymer blend demonstrates favorable properties for use in fruit coatings. In contrast to the 100% SHL film, the TAP:SHL coatings do not exacerbate anaerobic respiration‐related browning during storage assessment. The findings highlight TAP:SHL polymer blend as a promising renewable material for extending fruit shelf life postharvest.