Effect of Salicylic Acid on the Quality Characteristics of Apple Fruit (Golden Delicious and Red Delicious) During Storage Period

Apple has a long-term supply throughout the year because of its high storage capacity. Sometimes keeping this fruit in the cold storage room for a long time reduces the quality and marketability, thus making it unattractive for consumers. Recently, there has been an increasing interest in the use of natural compounds to maintain fruit quality and extend its shelf life. Salicylic acid (SA), a widely distributed compound in plants, belongs to a group of phenolic compounds. It could be considered an endogenous plant growth regulator involved in the regulation of physiological processes and disease resistance mechanisms.

To solve this problem, the effect of different concentrations of salicylic acid on the storage of golden and red delicious apple fruits was examined at harvest, 45, 90, 135 and 180 days after storage. Treatments included no washing, distilled water, and salicylic acid 1, 2, and 3 mM for half and 1 hours in cold storage room at 1 ± 2° C. At the end of each storage period, traits such as fruit firmness, vitamin C, TSS/TA, phenol, mealy fruit, flavor (panel test), chilling index and antioxidant capacity were evaluated in three storage periods (0, 90 and 180 days after storage). A factorial experiment based on a completely randomized design was conducted. In both cultivars, harvest index coincided with 170 days after full bloom.

Results showed that chilling injury, mealy and fruit ripening reduced by salicylic acid treatment and flavor maintained. Antioxidant capacity and phenol content increased by salicylic acid treatment during the storage, but no effect on vitamin C and fruit firmness was observed. During storage, maximum of chilling injury and flavor was related to yellow apple fruit and the maximum of tissue and skin firmness, vitamin C and antioxidant activity belonged to red apple cultivar. The use of 2 mM salicylic acid for half an hour was more effective than other treatments in preserving the quality and storage of fruit of both cultivars.

The results of this study showed that at the end of the storage period the amount of mealy fruit and flavor increased, while skin and tissue firmness decreased significantly. The effects of salicylic acid include a decrease in mealy fruit and chilling injury, as well as an increase in phenolic compounds and maintenance of the antioxidant activity, flavor and TSS/TA, which ultimately increased shelf life of apple fruits. High quality and storage capacity were related to red rather than yellow apple.