Effect of Near-freezing Temperature Storage on the Quality of Postharvest Fresh Waxy Corn

To investigate the effects of near-freezing temperature treatment on the storage quality of fresh waxy corn, the 'Huhongnuo 1' waxy corn was used as experimental material in this experiment. The waxy corn was stored at 4 ℃ and near-freezing temperature (−1 ℃) for 40 days, respectively. The changes in quality and the activities of antioxidant enzymes of fresh waxy corn during storage were determined, and correlation analysis and principal component analysis were performed. The results showed that compared with refrigerated storage at 4 ℃, near-freezing temperature treatment could effectively reduce the weight loss, inhibit the rise of fruit skin hardness, and maintain the content of moisture, soluble solids (TSS), soluble sugar, soluble protein and secondary metabolites. In addition, near-freezing temperature treatment could maintain a high level of total phenols, flavonoids and anthocyanins, and increase the activity of catalase (CAT), superoxide dismutase (SOD) and ascorbate peroxidase (APX), which reduced the accumulation of H₂O₂, maintained the nutritional quality of fresh waxy corn, and delayed fruit senescence. Correlation analysis showed that the storage time of fresh waxy corn was significantly positively correlated with the weight loss rate, fruit skin hardness and H₂O₂ content and was significantly (P<0.01) positively correlated with water content, TSS content, soluble sugar content, total phenols content, flavonoids content, anthocyanins content and APX activity. Principal component analysis and comprehensive score further showed that the key indicators affecting the storage quality of fresh waxy corn were flavonoids content, anthocyanins content, APX activity, fruit skin hardness, weight loss rate, H₂O₂ content, CAT activity and SOD activity. The near-freezing temperature treatment had better fresh-keeping effect, which was conducive to maintaining the storage quality of fresh waxy corn.