Revealing cold plasma-mediated changes in wolfberry wax and related gene expression during storage

Abstract

Cold plasma (CP) is promising for postharvest storage and processing of fruit. However, as the first surface material that CP interacts with, the effects of CP on the cuticular wax of fruit remain unclear. This study aimed to elucidate how direct treatment with dielectric barrier discharge plasma, at varying power levels, affects the structure, composition, and biosynthesis of wolfberry wax, and its implications on postharvest storage and drying. Our findings reveal a power-dependent response. High-power CP (>20 W) increased wax hydrophilicity, accelerating drying but potentially compromising storage stability due to increased water loss. Conversely, low-power CP (<20 W) caused minimal initial damage, with partial recovery observed during storage. Notably, 10 W treatment even promoted alkane accumulation after two days, potentially enhancing storage quality. High-power CP (40 W) induced changes in wax composition, transforming alkanes into alcohols, ketones, fatty acids, and lipids, while reducing long-chain alkanes and fatty acids, and increasing short-chain alcohols and esters. These changes were linked to the downregulation of genes involved in alkane hydroxylation, wax precursor synthesis, and the acyl reduction pathway. In contrast, 10 W treatment exhibited a milder and more targeted impact on specific wax biosynthesis steps. These findings provide insights into CP's effects on waxes, guiding CP processing for wolfberries and other fruit to enhance postharvest quality.