Submitted to: Florida State Horticultural Society Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2006
Publication Date: 6/4/2006
Citation: Plotto, A., Rattanapanone, N. 2006. Edible coatings for lychee fruit to maintain color in storage. Florida State Horticultural Society Meeting. Paper No. 38.
Technical Abstract: The bright red pericarp of lychee (Litchi chinensis Sonn.) fruit quickly turns brown after harvest due to peel dehydration, anthocyanin degradation, and fungal growth on the fruit surface. Lychee fruit, cv. Mauricious and Brewster from Florida, and Hong Hauy and Juckapat from Thailand, were dipped in acidic treatments (2-3% citric acid, 2% ascorbic acid, 2% acetic acid, 1% isoascorbic acid), antioxidants (0.5% acetylcysteine, 0.02% hexyl-resorcinol), antimicrobial treatments (peroxyacetic acid (Storox), 5 or 20% ethanol) and various coatings (chitosan, carrageenan, hydroxypropylcelulose [HPC], sucrose fatty acid esters, pectin oligomers, carnauba wax), alone or in combination. Ascorbic and citric acid gave the best results in the Thai experiments. HPC performed well on the Thai fruit, but not on the Floridian fruit. In the Florida experiments, the mixture of isoascorbic acid with acetylcysteine and hexylresorcinol, and 5% ethanol consistently gave higher chroma readings with the L*a*b* color measuring system, indicating higher color intensity. Ascorbic acid, isoascorbic acid, and acetylcysteine alone gave higher chroma in one experiment. Visual evaluation was higher for these treatments after 15 and 21 days storage at 5 °C, as well as for the sucrose fatty acid ester. There was a high anthracnose (Collectotrichum spp.) pressure for the Florida harvested fruit in the first year, and in the second year, Collectotrichum and Alternaria were isolated from the fruit surface. Future efforts will also aim at reducing pathogen pressure in the field, as well as after harvest.