Low temperature conditioning alleviates chilling injury in mango (Mangifera indica L. cv. Carabao) fruit

Chilling injury in mango and other tropical produce limits the efficacy of low temperature storage in extending the storage life and in maintaining the postharvest quality of harvested commodities. The potential of low temperature conditioning in alleviating chilling injury in mango fruits was evaluated. Green mature 'Carabao' mango fruits were subjected to different low temperature conditioning treatments of 10 deg C and/or 13 deg C for 3 days prior to storage at 7 deg C for 4 weeks. Starting on the 2nd week of storage, fruits were withdrawn weekly and rated for chilling injury symptoms. Physico-chemical properties and internal fruit quality were assessed after ripening at 25 deg C. Low temperature conditioning treatments alleviated chilling injury symptoms in 'Carabao' mango fruits stored at 7 deg C for 4 weeks. Conditioning at 13 deg C or 10 deg C for 3 days reduced the severity of peel discoloration, and prevented the development of vascular browning. On the other hand, reduced severity of lenticel spotting was observed in fruits conditioned for 3 days at 13 deg C and those conditioned for 6 days, i.e. 3 days at 13 deg C followed by 3 days at 10 deg C. A delay in the onset of diseases contributed to the slow rate of decline in visual quality of conditioned fruits, while non-conditioned fruits held at 7 deg C had a fast rate of visual quality decline due to lenticel spotting, peel discoloration and onset of diseases. Normal ripening proceeded in the cold-stored fruits when transferred to 25 deg C regardless of whether these were low temperature-conditioned or not as shown by the increase in peel color, decrease in titratable acidity and increase in total soluble solids content. Fruits conditioned at 10 deg C for 3 days prior to storage at 7 deg C were still of good visual and organoleptic qualities after 4 weeks of cold storage and subsequent ripening at 25 deg C. Fruits from this treatment extended the storage life at 7 deg C for 21 days and shelf life at 25 deg C for 8 days. Based on this study, chilling injury in 'Carabao' mango fruits following prolonged storage at 7 deg C is best alleviated when fruits are conditioned for 3 days at 10 deg C.