Retention of storage quality and post-refrigeration shelf-life extension of plum (Prunus domestica L.) cv. Santa Rosa using combination of carboxymethyl cellulose (CMC) coating and gamma irradiation

• Irradiation and CMC alone at 1.5 kGy and 1.0% gave 8 and 5 days extension in shelf life.
• Treatment of 1% w/v CMC+1.5 kGy inhibited decay up to21 days of ambient storage.
• Combination of 1% CMC and 1.5 kGy irradiation extended shelf-life of plum by 11 days.
• Combination treatment can help fruit marketing in glut season and enabling good returns.

Carboxymethyl cellulose (CMC) coatings alone and in combination with gamma irradiation was tested for maintaining the storage quality and extending shelf-life of plum. Matured green plums were CMC coated at levels 0.5–1.0% w/v and gamma irradiated at 1.5 kGy. The treated fruit including control was stored under ambient (temperature 25±2 °C, RH 70%) and refrigerated (temperature 3±1 °C, RH 80%) conditions. In fruits treated with individual treatments of 1.0% w/v CMC; 1.5 kGy irradiation and combination of 1.0% w/v CMC and 1.5 kGy irradiation, no decay was recorded up to 11, 17 and 21 days of ambient storage. Irradiation alone at 1.5 kGy gave 8 days extension in shelf-life of plum compared to 5 days by 1.0% w/v CMC coating following 45 days of refrigeration. All combinatory treatments of CMC coating and irradiation proved beneficial in maintaining the storage quality as well as delaying the decaying of plum during post-refrigerated storage at 25±2 °C, RH 70% but, combination of CMC at 1.0% w/v and 1.5 kGy irradiation was found significantly (p≤0.05) superior to all other treatments in maintaining the storage quality and delaying the decaying of plum. CMC coating of plums at 1.0% w/v followed by irradiation at 1.5 kGy resulted in chlorophyll retention of 19.4% after 16 days compared to 10% in control after 8 days of ambient storage. Under refrigerated conditions, same treatment gave retention of 67.6% in chlorophyll compared to 10.6% in control after 35 days of storage. The above combinatory treatment resulted in extension of 11 days in shelf-life of plum during post-refrigerated storage at 25±2 °C, RH 70% following 45 days of refrigeration. Based on microbial analysis, irradiation alone at 1.5 kGy and in combination with 1.0% w/v CMC resulted in 2.0 and 1.8 log reduction in yeast and mold count of plum fruit after 20 and 35 days of ambient and refrigerated storage, thereby ensuring consumer safety.