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Superficial scald assessment on 'Granny Smith' apples stored under dynamic controlled atmosphere in commercial operations in Chile

Torres, C. A., Hernandez, O.
Acta horticulturae 2015 no.1079 pp. 421-428
apples, cold storage, color, controlled atmosphere storage, diphenylamine, ethylene, firmness, fruit maturity, fruit quality, fruits, growers, metabolites, scald diseases, storage time, temperature, total soluble solids, world markets, Chile, Europe
After diphenylamine was removed from the list of authorized pesticides in Europe, Chilean growers and packers had to search for alternative technologies for superficial scald (SS) control on susceptible apples, such as ‘Granny Smith’. Thus, dynamic controlled atmosphere storage (DCA) was rapidly adopted by large size operations as a non-chemical alternative for maintaining fruit quality and controlling SS. Nevertheless, Chilean fruit travels long distances to international markets, therefore, after fruit is removed from DCA it might be maintained for 30, 60 or more days in cold storage (including travel time) before reaching the final consumer. This situation has challenged DCA’s capability to control SS. The objective of this work was to assess SS expression on fruit stored in DCA and then maintained in cold storage for up to 90 days (‘transit RA’). Fourteen batches of ‘Granny Smith’ apples were sampled from 5 commercial DCA rooms located in the Maule Region, Chile. Three replicates (300 fruits each) were stored for 30, 60, and 90 days in RA (0-1°C, >90% RH) plus 14 days at 22°C after being removed from commercial DCA. Maturity indices (color, flesh firmness, soluble solids, ethylene concentration), and SS incidence, and metabolites associated with SS (α-farnesene, conjugated trienols) were determined after each storage period. Superficial scald symptoms appeared as light brown patches diffused into the skin in all batches evaluated. After 30 days in transit RA, 58% of the batches had between 1-32% SS, after 60 days 79% of the batches had between 3-95% SS, and after 90 days 100% of the batches had between 6-100% incidence. Fruit maturity pre-DCA storage could not explain differences in expression timing between batches of fruit. No differences in α-farnesene or conjugated trienols concentration were found among batches with different SS levels. In conclusion, the longer the ‘transit time’ (in low temperature) after DCA removal the higher the SS incidence on ‘Granny Smith’ apples, once fruit is exposed to higher temperatures.