Evaluation of Physico-biochemichal Characteristics of Fruits in New Varieties of Noushin and Shahin Mandarins During Storage

According to a breeding program that was carried out in Citrus and Subtropical Fruits Research Center, Noushin (C. reticulata cv Clementine × C. sinensis cv. Salustiana) and Shahin (C. reticulata cv Clementine × C. sinensis cv. Hamlin) mandarins were released by using crossing method in 20-year program. In general, mandarins do not have the ability of being kept in common or cold storage for long time compared to oranges. The main problem is the change of fruit taste during storage, therefore, it is an attracted subject for researchers. Furthermore, storage temperature plays an important role in the quality of the taste of mandarins. The new released mandarins, which hve not been yet studied completely for their storability, need to be evaluated. Therefore, the aim of this study was to investigate fruit physico-chemical and sensory characteristics of Noushin and Shahin varieties in common and cold storages for two years.
In this study, fruits of Noshin and Shahin mandarins were harvested at seasonal harvesting time and then placed in could storage (5 oC and 85% RH) and common storage (7-10 oC and 60-70 %RH) based on completely randomized design with three replications for 60 days every year. Fruits on days 0 (at harvesting time), 20, 40 and 60 of storage were sampled. Various physico-chemical and sensory characteristics were evaluated including iuice percentage, weight loss, peel color indices (L*, a*, b*, hue angle, chroma and CCI), total soluble solid (TSS), titratable acidity (TA), technological index (TI), skin disorder index (SDI), pH, electrical conductivity (EC), total phenolic, ascorbic acid, antioxidant capacity and sensory parameters during experiment. Statistical analysis of the data was performed using statistical software MSTAT-C. Analysis of variance combined in a randomized complete design (two years) with three replications for each variety.
The results showed that the amount of fruit weight loss and juice percentage did not show significant changes during storage. The ranges of weight loss in Noushin and Shahin varieties were 7-8% and 3.45-5.1%, respectively. Generally, peeling in Shahin was harder than Noushin but it gradually decreased until the end of storage. With the exception of citrus color index (CCI) in Noushin that was high at the beginning of storage, other color indices had no significant differences according to the type of variety and storage. Totally, TSS: TA ratio increased during storage depending on the type of storage, so that the ratio was higher (Noushin with 39.64 and Shahin with 13.34) in common storage than cold storage (Noushin with 31.04 and Shahin with 13.62) at the end of storage. Amount of electrical conductivity (EC) and technological index (TI) increased significantly in both varieties and storages. Shahin variety with 3.74 and 26.19% was so sensitive to rind disorder index and rind disorder percentage, respectively. Phenolic compounds in both varieties declined during both cold and common storages. The amount of reduction depends on the type of mandarin, with Shahin showing higher decline than Noushin variety. Besides, the content of ascorbic acid and antioxidant capacity in both peel and pulp showed a decreasing pattern with the passing of harvesting time during storage. According to sensory analysis, Noushin fruit can be stored in common storage for 20 days and in cold storage for 40 days. Moreover, results revealed that Shahin fruits did not have storability more than 40 days in common and cold storages.
Generally, Noushin variety was sensitive to low moisture of the storage and fruits lost extra moisture during storage. Since Noshin was an early ripening variety, TSS: TA ratio increased rapidly at the end of storage. Although Noushin had the lowest ascorbic acid content but its fruit antioxidant capacity was higher than shahin at the end of storage. On contrast, Shahin was a mid-ripening variety with higher ascorbic acid content. On the other hand, shahin peel was so sensitive to skin disorder index (SDI), therefor it should not be maintained in low moisture and temperature storage. Based on sensory analysis and physicochemical measurements, Noushin can be stored for 20 days and shahin for 40 days in common and cold storage. Finally, we found that Noushin and Shahin cannot be maintained in storage longer than other mandarins.