Synergistic effect of gamma irradiation and sodium alginate coating on postharvest quality and shelf-life extension of plum fruit (cv. Santa Rosa).

This study evaluated the combined effect of gamma irradiation (1.5 kGy) and sodium alginate (SA) coating (1-4%) on the postharvest quality and shelf-life of plum fruit. Fruits were stored at 1-2 °C for 35 days and subsequently held under ambient conditions (25 ± 2 °C). At day 35 of refrigerated storage, the combined treatment of 4% SA + 1.5 kGy retained the highest firmness (39.09 N) compared with the control (15.96 N) and SA-only treatments (15.92-27.48 N). Physiological weight loss was reduced from 17.45% in the control to 4.32% in the 4% SA + 1.5 kGy treatment. No decay was detected in any irradiated treatment throughout 35 days, whereas the control showed 39.50% decay. Yeast and mold counts at day 35 were lowest in the 4% SA + 1.5 kGy treatment (3.00 log CFU g-1) compared with the control (5.08 log CFU g-1).Based on combined acceptability criteria (sensory score ≥ 7, microbial load <4 log CFU g-1, decay <10%), the 4% SA + 1.5 kGy treatment extended refrigerated shelf-life to 35 days and ambient shelf-life to 6 days. The results demonstrate that the combined application of sodium alginate coating and gamma irradiation effectively improves quality retention and shelf-life of plum fruit under refrigerated and subsequent ambient storage.