EFFECTS OF ALGINATE EDIBLE COATING ENRICHED WITH SALICYLIC AND OXALIC ACID ON PRESERVING PLUM FRUIT (Prunus salicina L. cv. 'BLACK AMBER') QUALITY DURING POSTHARVEST STORAGE

The effect of alginate treatments with or without salicylic and oxalic acid as post-harvest coating in extending the postharvest life of plums (Prunus salicina L. cv. 'Black amber') and maintaining their quality were investigated. Plums were treated with 2% alginate coating with or without salicylic (1.0 mM) and oxalic acid (1.0 mM), and then stored at 0-1 degrees C and 90 +/- 5% relative humidity for 40 days. The quality of plums was assessed at 10-day intervals by evaluating the following quality parameters: weight loss, soluble solids content, titratable acidity, firmness, respiration rate, ascorbic acid content, total anthocyanin content, total phenolic content and antioxidant activity. The respiration rate, weight loss and changes in quality parameters were much lower in coated plums as compared with the control. Alginate coating resulted in a significant reduction in weight loss of fruits. Alginate treatments with or without salicylic and oxalic acid were effective on delaying the evolution of parameters related to postharvest ripening, such as soluble solids content, softening and reducing respiration rate. At the end of the storage period, the edible coatings showed a positive effect on maintaining higher concentration of total phenolics, total anthocyanin content and antioxidant activity, which decreased in control plums as a result of over-ripening and senescence processes. The results suggested that the use of alginate enriched with salicylic acid could maintain considerably higher quality of fruits and level of bioactive compounds than other coating treatments during 40 days of storage at 0-1 degrees C.