Impact of -PL treatment on postharvest quality of 'Jinxiu' yellow peach (Prunus persica L.)

To investigate the effectiveness of epsilon-polylysine (epsilon-PL) on fruit senescence related to quality and antioxidase activity in 'Jinxiu' yellow peach, and to explore the relationship between cold injury and antioxidant activity of peach fruit. Peaches reached an eighth mature stage were subjected to postharvest immersion treatment with five concentrations (0, 100, 300, 600 and 900 mg L-1) of epsilon-PL solutions for 15 min. Treated peaches were stored at (0 +/- 0.5) degrees C and 80-85% relative humidity for 42 days. The results confirmed that the epsilon-PL treatment effectively reduced weight loss, delayed total color changes, reduced internal flesh browning and improved the peach quality. And this was correlated with delayed senescence, which is due to the inhibition of respiration rate and peak, decrease in MDA accumulation, reduce relative membrane permeability and PPO, and enhance antioxidase activity of the fruit. PCA analysis results identified that comparatively better response of epsilon-PL application on peach fruit storage quality, accompanied by the extension of cold storage time, indicating significant differences among groups. Furthermore, the 600 mg L-1 epsilon-PL group was better at lengthening storability; the percentage of MDA, relative membrane permeability and PPO was 19.35%, 18.54% and 30.44% lower than the control at 42 days, respectively. The group also maintain the sensory quality of the yellow peach for up to 42 days during cold storage than other groups. Consequently, these findings suggested that applying epsilon-PL to peach during postharvest is practical way to reduce chilling injury, delay fruit senescence and preserve the fruit quality.