Effects of Hot Water Treatments on Antioxidant Enzymatic System in Reducing Flesh Browning of Persimmon

The flesh browning that appears during commercialization period is the main postharvest disorder that is limiting the market of "Rojo Brillante" persimmon in the Mediterranean area. Previous studies have suggested that mechanical damage suffered by the fruit during packing line operations is the trigger of this alteration when fruit is previously subjected to the required deastringecy treatment. In the present work, the effect of hot water treatments (HWTs) on flesh browning incidence of Rojo Brillante persimmon has been investigated. For that, fruits submitted to the commercial deastringency treatment were hot water treated at 45 A degrees C for 30 min or 50 A degrees C for 20 min and then subjected to different intensity of mechanical damage in packing line. Fruit bathed at 25 A degrees C for 25 min and fruit hand-packed acted as control treatments. Our results confirmed that mechanical damage during packing is a decisive factor in the incidence of flesh browning, and this alteration is found to increase the damage intensity. HWTs significantly alleviated flesh browning disorder by affecting the antioxidative system enzymes; the activity of catalase and ascorbate peroxidase was increased by HWTs while the activity of peroxidases was reduced. No changes were observed in polyphenol oxidase and phenylalanine ammonia lyase activity. Therefore, the application of HWTs may be a useful postharvest technology to reduce flesh browning of persimmon induced by packing line operations

Changes in pectin methylesterase, polygalacturonase, catalase and peroxidase activities associated with alleviation of chilling injury in persimmon by hot water and 1-MCP treatments

'Rojo Brillante' persimmon is an astringent cultivar whose fruits are chilling injury-sensitive. A pretreatment of 1-MCP or Hot Water before cold storage is known to alleviate flesh softening, the main chilling injury symptom to occur when fruit is transferred from low to moderate temperatures. In order to better understand the chilling injury alleviation mechanism in persimmon through these two treatments, the changes of antioxidant system enzymes (catalase and peroxidase) and cell wall degrading enzymes (pectin methylesterase and polygalacturonase) were evaluated. Persimmon fruits subjected to the 1-MCP treatment (500 nL L-1) or to hot water treatments (45 degrees C for 30 min) (HWT-45 degrees C) and 50 degrees C for 20 min (HWT-50 degrees C) were stored at 1 degrees C for 30 days. Then they were submitted to a deastringency treatment (98% CO2 at 20 degrees C for 24h) before being transferred to shelf-life conditions for 5 days at 20 degrees C. The HWT applied at 50 degrees C and 1-MCP were observed to be the most effective treatments to reduce firmness loss after cold storage. During the shelf-life period, the activities of pectin methylesterase and polygalacturonase were lower in fruit treated with both treatments than in control fruit, which may result in higher cell wall integrity and, therefore, in fruit softening alleviation. The 1-MCP and HW-treated fruits exhibited higher catalase and lower peroxidase activities if compared to untreated fruit. While peroxidase activity was especially inhibited by 1-MCP, HWT exerted a more marked effect on the catalase enzyme. The changes in cell wall degrading and antioxidant system enzymes induced by 1-MCP and HWT-50 degrees C during the symptom development period reveal that these enzymes are involved in the chilling-tolerance of persimmon. (C) 2014 Elsevier B.V. All rights reserved

Pre-harvest CaCl2 and GA3 treatments improve postharvest quality of green bell peppers (Capsicum annum L.) during storage period

The present study investigated the effects of CaCl2 (0.5) and GA₃ (0.05 g L−1) pre-harvest treatments both at two (2T) and three spraying times (3T) on some qualitative characteristics of green bell pepper stored for 0, 10 and 20 d at 1 and 10 °C. The purpose of this study was to mitigate postharvest lesions and increase chilling injury resistance in peppers. Weight loss, firmness, total soluble solids (TSS), vitamin C (VitC), phenolics, electrolyte leakage (EL), malondialdehyde (MDA), chilling injury, chlorophyll and calcium contents, peroxidase (POD), catalase (CAT) and antioxidant activities were measured. The highest and lowest weight losses were observed after 20 d at 1 and 10 °C on control and CaCl2 treatments respectively. The highest (30.8 at 1 and 21.4 N at 10 °C) and lowest (23.5 at 1 and 14.2 N at 10 °C) firmness was measured in fruit from the CaCl2 (3T) treatment and control, respectively. The amount of VitC and phenolics were higher in the control compared to all other treatments. After 20 d, the highest amount of MDA and EL, as well as the lowest amounts of calcium were measured in the control, gibberellin and calcium treatments, respectively. Chilling injury increased after 20 d of storage at 1 °C. However, all treatments with no significant difference had less chilling injury and TSS and more antioxidant enzymes (POD and CAT) and chlorophyll than the control. The results reveal that all CaCl2 and GA₃ treatments increased overall quality of pepper at harvest time and preserved the quality and reduced the chilling injury during the storage period. Hence, these treatments can be commercially effective strategy to improve shelf life and maintain the quality of green bell pepper fruit during harvest and postharvest