EFFECT OF 1-MCP ON ´ABBÉ FÉTEL´ PEARS SORTED AT HARVEST BY TIME-RESOLVED REFLECTANCE SPECTROSCOPY

Abstract

1-Methylcyclopropene (1-MCP) is an inhibitor of ethylene action, but its effectiveness and dose response in pears is variable from year to year and seems to be related to fruit maturity. In order to try to tune the 1-MCP dose at each maturity stage, 'Abbe Fetel' pears were picked on 1 September 2003, analysed by time-resolved reflectance spectroscopy (TRS), a new non destructive method for assessing fruit maturity, obtaining the absorption coefficient at 690 nm (μ a 690) for every fruit. Then pears were ranked by decreasing μ a 690 and divided into two maturity classes (less and more mature). Fruits in each class were randomised between the 1-MCP (0, 100 and 300 ppb) and storage (-0.5°C, NA or CA 2% O 2 + 0.7 % CO 2 ) treatments. 1-MCP was applied on the day after harvest at -0.5°C for 30 h. Analyses of fruit mass, colour, firmness, soluble solids (s.s.) and titratable acidity were carried out at harvest and, along with ethylene production rate, after 4 and 6 months' storage and during shelf life (7 days at 20°C). At harvest, μ a 690 was correlated to s.s., mass and titratable acidity, but not to firmness. After storage, the selection of fruit according to maturity affected fruit colour and the susceptibility to superficial scald, especially in control fruits stored in NA. In this experiment, on average, treated fruit were not able to soften below 40 N. So TRS measurement of μ a 690 on 'Abbe Fetel' pears could be used as maturity index at harvest for this cultivar; however, due to the strong effect of 1-MCP treatment, even at 100 ppb, the response of less and more mature fruit was not very different as regards firmness and ethylene production. More data are needed to check if there could be a relation between the maturity stage as assessed by TRS, and the optimum 1-MCP dose for both ripening and control of superficial scald.