A gas-permeable edible coating alleviates CO2-induced off-flavor formation and reduces weight loss in postharvest citrus fruit.

Abstract

Coating can reduce fruit weight loss and delay wrinkling, but often induces off-flavor formation. This study aims to develop coatings for reducing off-flavor formation in citrus fruits. Initially, nine single-component edible coatings were screened, identifying lipid-based carnauba (CNW) and candelilla wax (CW) as the most effective in reducing off-flavor and weight loss, respectively. Twenty CW-CNW composite coatings (ECs) were then formulated, with EC14 (2% CNW + 8% CW) showing optimal performance. The ethanol, acetaldehyde, and weight loss in EC14-coated Satsuma mandarin were 20.25%, 28.78%, and 34.15% of those in commercial-coated fruits, respectively. EC14 also suppressed respiration, maintained firmness, and was suitable for multiple citrus varieties. Correlation analysis and CO2-injection experiment confirmed that excessive internal CO2 drives off-flavor formation. EC14 with superior gas permeability reduces internal CO2 levels and enhances antioxidant capacity, thereby alleviating CO2-induced off-flavor and physiological damage and improving the storability. This study provides an effective solution to off-flavor in coated citrus fruit.