No abstract

An inhibitory effect of sucrose laurate ester (SLE) on the degreening of Nagato-yuzukichi (Citrus nagato-yuzukichi hort. ex Y. Tanaka) fruit was determined. SLE treatment suppressed the degreening of the fruit during 5 storage at 20 more efficiently than the treatment with any other sucrose fatty acid ester, such as myristate, palmitate or stearate. SLE, itself did not have an inhibitory effect on the chlorophyllase and chlorophyll (Chl)-degrading peroxidase activities, but laurate, which was de-esterified from SLE, had a significant effect. Laurate inhibited both enzyme activities more effectively 10 than any other fatty acid, such as caprylate, caprate, myristate, palmitate or stearate. The fruit flavedo extract had an activity to decompose SLE to laurate and sucrose, and treatment of the fruit with laurate significantly suppressed degreening during storage at 20 as well. These results indicate that the suppression of degreening in SLE-treated Nagato-yuzukichi fruit could be in 15 part due to the formation of laurate from SLE by esterase, such as a lipase, which is present in the flavedo, and the formed laurate might be involved effectively in the inhibition of Chl-degrading enzyme activities. Moreover, the suppression of degreening by SLE treatment could be owing to the inhibition of degreening by laurate in addition to the coating effect of SLE.