Submitted to: Journal of Food Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/4/2003
Publication Date: 3/12/2004
Citation: Lamikanra, O., Watson, M.A. 2004. Temperature and storage duration effects on esterase activity in fresh-cut cantaloupe melon.. Journal of Food Science. Interpretive Summary: Our laboratory recently demonstrated that the staleness that occurs during the refrigerated storage of fresh-cut cantaloupe melon could be the result of the loss of compounds that are responsible for their fruity character (esters). The effect of storage of fresh-cut cantaloupe melon on the enzyme (esterase) that initiates this loss was determined. Enzymatic activities, after the first day of storage, were reduced by 40 and 10 % in fruit stored at 4 oC and 15 oC respectively. The higher enzymatic activity at the time of processing is apparently due to the initial fruit tissue adaptation to wound stress. Esterase enzyme activity in the fruit also appears to be controlled by other protein degrading enzymes, and the enzyme is thermally unstable. Our results suggest that the esterase-mediated loss of esters in fresh-cut cantaloupe melon is initiated at the time of cutting, and before storage. The information will be useful to the fresh-cut fruit industry for developing methods to improve the shelf life of cut fruits.
Technical Abstract: The effect of storage on esterase (ES) activity in fresh-cut cantaloupe melon (Cucumis melo L. var. reticulatus Naud) was determined at 4 and 15 oC. Enzymatic activity, after the first day in storage, was reduced by 40% and 10% in fruit stored at 4 and 15 oC respectively. The ES in cantaloupe melon was determined to be carboxylesterase with two isozymes (pI=6.1 and pI = 9.5) and low thermal stability. Pectin methyl esterase activity in the cut fruit also decreased by about 25% at both temperatures after a day in storage, but considerably increased after 3 days storage at 15 oC. Enzyme inhibition studies indicate that ES in cantaloupe melon appears to be regulated by metalloproteases, presumably metallo-exoproteases.