Chilling Injury in Mamey Sapote Fruit (Pouteria sapota): Biochemical and Physiological Responses

Problem statement: Cold storage is needed in order to delay senescence and achieve a longer commercial life of tropical fruits like mamey sapote (Pouteria sapota), therefore, the physiological and biochemical responses of this fruit to cold storage were evaluated. Approach: Samples from different storage temperature (20, 10 and 2°C) were taken at five-day intervals and Chilling Injury Index (CII), decay (%), pulp firmness, weight loss (%), sucrose, fructose and glucose contents, electrolyte leakage (%), ethylene and carbon dioxide production rates and the activities of Peroxidase (POD), Polyphenoloxidase (PPO) and Phenylalanine Ammonia-Lyasa (PAL), were evaluated. Results: CII of fruit stored at 2 and 10°C was similar and symptoms included abnormal ripening into trimming zones close to the skin and pulp. Development of CI symptoms was more evident after 10 days of storage at 2 and 10°C. This trend may be associated with decrease of sucrose content but not with fructose that increased on fruits stored at 2°C (p<0.05). For mamey fruits stored at 2°C, the PAL activity was significant lower than in the fruits stored at 10°C, but it did not increase in response to the chilling temperature. No appreciable changes on POD activity were observed in fruit stored at 2°C. PPO activity continuously decreased on fruit stored at 2°C and similar behavior was observed on fruit stored either at 10 and 20°C, during the first 15 days of storage. Conclusion: Our results demonstrated the sensitivity to mamey sapote fruits to low storage temperatures (2 and 10°C). Symptoms developed by fruit include abnormal ripening into trimming zones close to skin, as well as darkened zones into middle pulp. Sucrose content could be a better chilling injury indicator in mamey sapote than electrolyte leakage, ethylene production and POD, PPO and PAL activities.