Influence of edible coatings on physiological and biochemical attributes of Japanese plum (Prunus salicina Lindell cv. Santa Rosa)

Introduction - 'Santa Rosa' plum is a very delicate fruit with a limited shelf life owing to decay and mechanical injury. Hence, edible coatings were attempted (on-farm and off-farm) in 'Santa Rosa' plum to increase fruit shelf life and marketability. Materials and methods - 'Santa Rosa' fruits were treated with edible coatings, namely, Semperfresh (TM) (1:3), vegetable wax (1:5), shellac-based wax (2:3) and water dip (control) at two different locations, viz., on-farm and off-farm (in the lab) and then stored at 20 +/- 2 degrees C. Quality evaluation of stored plums was carried out for changes in the firmness, physiological (loss in weight, respiration and ethylene evolution rates) and biochemical attributes (total antioxidant activity, malondialdehyde content and pectin methylesterase activity) at 3-days interval for a period of 15 days. Results and discussion - On-farm treated fruits showed maximum retention in firmness as compared to the untreated fruits. Respiration rate and ethylene evolution rates were also delayed significantly in coated fruits. Amongst the different coatings applied, shellac-based coating was found to be the best in maintaining maximum firmness (similar to 67% higher) and overall fruit quality followed by Semperfresh (TM) and vegetable wax coatings. Off-farm coated plums were inferior in quality to on-farm treated ones. Conclusion - On-farm treatment of plum fruit with shellac-based coating showed the best results in maintaining the firmness, quality and postharvest life of plum up to 15 days.