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Considering the nutritional value of fruits and vegetables, maintaining and preserving the quality and increasing the shelf life of these products is very important. Due to the high moisture level, the mulberry fruit has a soft and highly perishable texture, which reduces the life after harvesting of this fruit. Therefore, it is very important to use methods to increase the durability of this product. One of the goals of this research is to investigate the effect of melatonin on the life after harvesting of white berry products stored in cold storage. For this purpose, after selecting suitable and identical fruits, melatonin foliar spraying was done at five levels with concentrations of zero (distilled water as a control), 125, 250, 500 and 1000 micromolar. Then the fruits were divided into 5 groups according to the treatment and kept in the cold room at 1 degree Celsius for 12 days. Random sampling was done every 4 days from among the fruits on days 0, 4, 8 and 12 of storage to evaluate and measure traits. Based on the results of the experiment during the storage period, fruit weight, ascorbic acid, acidity, pH and L* decrease and factors of soluble solids, phenol, flavonoid, polyphenol oxidase enzyme activity (PPO), antioxidant capacity (DPPH), H2O2 and Malondialdehyde (MDA) increased. Melatonin treatment increased the amount of ascorbic acid, soluble solids, phenol and flavonoid. It also decreased the amount of weight loss, H2O2 concentration, MDA and PPO enzyme activity. Another way to preserve fruit is to use processing methods such as drying. Drying is a very effective and practical method to preserve the fruit and reduce losses after harvesting. The second experiment was conducted with the aim of the effect of solar drying and ohmic heating in increasing the life after harvesting of white berries. Drying treatments included (T0: control, T1: direct return without moisture absorber, T2: indirect return without moisture absorber, T3: direct without return and without moisture absorber, T4: direct return with moisture absorber). According to the results of the second experiment, the amount of phenol in the direct treatment without return and without moisture absorber and the amount of ascorbic acid in the direct treatment without return and without moisture absorber and direct return with moisture absorber decreased compared to the control treatment. Also, the amount of flavonoids increased in the direct return treatment without moisture absorbent and indirect return treatment without moisture absorbent compared to the control treatment. Based on the results of ohmic heating in white berry, the amount of phenol and flavonoids in different treatments of ohmic heating significantly decreased compared to the control treatment. In addition, changes in ohmic heating treatments showed different effects on DPPH. According to the results, the positive effects of melatonin treatment at a concentration of 1000 micromoles of melatonin were more than other concentrations. Also, based on the results of the second experiment, no positive effects of solar drying and ohmic heating treatments were observed on the measured traits
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