L-cysteine and L-methionine application preserve strawberries by reducing fruit decay and maintaining postharvest fruit quality

This study investigated the efficacy of exogenous L-cysteine (L-Cys) and L-methionine (L-Met) in preserving postharvest quality and extending shelf life of strawberry cultivars ‘Benihoppe’ and ‘Fenyu No.1’. Fruits were treated with varying concentrations (L-Cys at 0.01–0.2 % and L-Met at 0.5–100 mM) and stored under controlled conditions. Results showed that 0.1 % L-Cys and 50 mM L-Met optimally reduced weight loss by 16.3 % and 40.4 %, respectively, and decay incidence by 24.5 % and 35 % compared to controls. Both treatments maintained higher ascorbic acid (AsA) levels, with L-Met being more effective, while differentially modulating phenolic metabolism. L-Cys increased total phenolic content by up to 42 % but suppressed anthocyanins. High-performance liquid chromatography (HPLC) analysis revealed cultivar-specific effects on organic acids: L-Cys increased citric acid by 23.5 % in ‘Benihoppe’, whereas both amino acids reduced it in ‘Fenyu No.1’. Oxidative stress markers exhibited cultivar-dependent responses, with L-Cys and L-Met reducing malondialdehyde (MDA) by 18–27 % but sometimes increasing hydrogen peroxide (H₂O₂). L-Met preserved antioxidant enzyme activity, maintaining superoxide dismutase (SOD) 18–22 % higher than the control, while catalase (CAT) remained stable. These findings highlight the role of sulfur-containing amino acids (SAAs) in quality preservation, and supports L-Cys and L-Met as safe, effective alternatives to traditional preservatives for strawberries.