Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 19, 2003
Publication Date: May 1, 2003
Citation: Fish,W.W., Davis,A.R. 2003. The effects of frozen storage conditions on lycopene stability in watermelon tissue. Journal of Agricultural and Food Chemistry. 51(6):3582-3585. Interpretive Summary: A number of positive health benefits can be derived from consumption of diets high in lycopene, the red pigment in watermelon and tomatoes. The purpose of this investigation was to evaluate the rate of deterioration of lycopene in watermelon tissue during frozen storage. This was undertaken because little is known about the stability of watermelon tissue lycopene under cold storage conditions, and many watermelon breeders have to collect and store samples before sending them off for lycopene analysis. Watermelon tissue stored at -20C lost 15% of its lycopene in the first month of storage and about 40% after a year's storage. Watermelon tissue stored at -80oC lost about 10% of its lycopene after a year's storage. The results of this investigation offer guidelines for frozen storage of watermelon tissue to enable the breeder an accurate estimate of lycopene content of the fresh tissue.
Technical Abstract: The purpose of this investigation was to evaluate the rate of deterioration of lycopene in watermelon tissue during frozen storage since little is known about the stability of watermelon tissue lycopene under cold storage conditions. Heart tissue from each of nine individual watermelons was stored at -20C or -80C as either small chunks or puree and periodically sampled over a year's time. Initial freeze-thaw experiments indicated that a small percentage of lycopene, ~4-6%, degraded during an initial freeze-thaw. Analyses of the samples showed a loss of ~ 30-40% lycopene over a year's storage at -20oC and a loss of ~ 5-10% over the same period at -80C. Watermelon tissue is equally-- or slightly more stable stored as a puree rather than chunks. The kinetic data were best fitted by application of two simultaneous, first order decay processes. HPLC analysis of the samples after a year's storage suggested that b-carotene was more stable to storage at -20C than was lycopene.