Melatonin-mediated postharvest quality and antioxidant properties of fresh fruits: A comprehensive meta-analysis.

At postharvest, fruits have a short shelf life. Recently, there has been much literature on the effects of melatonin on the postharvest quality of horticultural crops. However, reports of various findings comprise mixed claims and product-specific conclusions. Therefore, a meta-analysis systematically dissects the comprehensive effect on several fruits. In this meta-analysis, standard mean difference (SMD) was adopted using a random-effect model. The study used 36 articles and isolated 24 indicator parameters of postharvest quality and antioxidant properties based on the inclusion criteria. As exhibited in the forest plot, melatonin reduced chilling injury, weight loss, respiration rate, and ethylene content (SMD -0.90, 95% CI [-1.14, -0.65]; I2  = 81%; p < .00001). Similarly, the application of melatonin significantly suppressed electrolyte leakage, malondialdehyde (MDA), hydrogen peroxide, superoxide anion, lipoxygenase, and polyphenol oxidase (SMD -0.89, 95% CI [-1.09, -0.69]; I2  = 70%; p < .00001). In addition, exogenous melatonin application induced endogenous melatonin content, phenolic content, and flavonoid and anthocyanin contents (SMD 1.15, 95% CI [0.91, 1.39]; I2  = 71%; p = .01). Moreover, melatonin treatment enhanced antioxidant activities (catalase, superoxide dismutase, peroxidase, ascorbate peroxidase, and phenylalanine ammonia-lyse) (SMD 1.37, 95% CI [1.03, 1.71]; I2  = 86%; p < .00001). Thus, in the whole study, the overall effect was significantly high in treated fruit (p < .0001), and the overall heterogeneity was above (I2 ) > 70%. In addition, the funnel plot showed symmetry in the most selected studies. To sum up, the result gives a further understanding of melatonin's capabilities in reducing postharvest losses and maintaining the quality of fresh fruits.

Effect of Cutting Styles on Quality and Antioxidant Activity of Stored Fresh-Cut Sweet Potato (Ipomoea batatas L.) Cultivars.

The effect of cutting styles (slice, pie, and shred) on the quality characteristics and antioxidant activity of purple and yellow flesh sweet potato cultivars during six days of storage at 4 °C was investigated. The results indicated that the sliced and pie samples showed no significant difference (p > 0.05) on the firmness, weight loss, and vitamin C content compared with the whole sweet potato in both cultivars during storage. The pie sample exhibited the highest wound-induced phenolic, flavonoid, and carotenoid accumulation and DPPH radical scavenging activity among the cuts in both cultivars. Moreover, the shredded sample showed significantly (p < 0.05) higher polyphenol oxidase (PPO) activity but lower total phenolic and flavonoid content and the lowest antioxidant activity among the samples. Thus, the finding of this study revealed that pie-cut processing has potential in improving the quality and increasing the antioxidant activity of fresh-cut purple and yellow flesh sweet potato cultivars while shredding accelerated the quality deterioration of both sweet potato cultivars.