New Zealand Journal of Crop and Horticultural Science abstracts

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Effect of surface coating on ripening and early peel spotting in ‘Sucrier’ banana (Musa acuminata)

S. Promyou
S. Ketsa*

Department of Horticulture
Faculty of Agriculture
Kasetsart University
Bangkok 10900, Thailand
email: agrsck@ku.ac.th

W. G. Van Doorn

Wageningen University and Research Centre
P.O. Box 17, AA 6700 Wageningen
The Netherlands

Abstract ‘Sucrier’ bananas (Musa acuminata, AA Group) show peel spotting when the peel is just about as yellow as green, which coincides with optimum eating quality. As consumers might relate the spotting to overripe fruit, early spotting is considered undesirable, especially for export markets. Fruit were left uncoated (controls) or coated with polyethylene parafilm wax at concentrations of 20%, 25%, and 30% (v/v) and then held at 29–30°C for 5 days. Compared with controls, each of the concentrations delayed early peel spotting. Eating quality was not affected by the 20% coating, but was negatively affected by the higher concentrations. Further tests, using 20% coating, showed that the delay of peel spotting was not associated with a change in peel total free phenolics or with polyphenol oxidase (PPO) activity, but it was accompanied by reduced in vitro phenylalanine ammonia lyase (PAL) activity. Results suggest that the delay in peel spotting, after surface coating, is a result, at least in part, of reduced PAL activity. Low rate of oxygen diffusion through the coating might be the factor that limits the last step to blackening.

Keywords banana; free phenolics; phenylalanine ammonia lyase; polyphenol oxidase; peel spotting; surface coating

New Zealand Journal of Crop and Horticultural Science, 2007, Vol. 35: 259–265
0014–0671/07/3502–0259 © The Royal Society of New Zealand 2007
*Author for correspondence.
H05139; Online publication date 15 May 2007. Received 31 October 2005; accepted 8 November 2006

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