FLESH QUALITY AND LYCOPENE STABILITY OF MINIMALLY PROCESSED WATERMELON

Authors: Perkins Veazie, Penelope; Collins, Julie

Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2003
Publication Date: 1/1/2004
Citation: Perkins Veazie, P.M., Collins, J.K. 2004. Flesh quality and lycopene stability of minimally processed watermelon. Postharvest Biology and Technology. 31:159-166.

Interpretive Summary: Watermelon is an excellent source of a naturally occurring red pigment called lycopene. Diets rich in lycopene may protect against cancer incidence and heart disease. This study was conducted to determine if cutting watermelon into cubes and storing in small containers resulted in loss of sugars, color and lycopene. Researchers found slight losses in sugars, color and lycopene when cubes were stored for 7 days or longer at 2C. These findings suggest that cut watermelon should not be stored for 7 or more days because of loss of quality.

Technical Abstract: Red fleshed watermelon is an excellent source of the phytochemical lycopene. However, little is known about the stability of lycopene in cut watermelon. In this study, lycopene stability and other quality factors were evaluated in minimally processed watermelon. Twenty melons each of a seeded ('Summer Flavor 800') and a seedless watermelon ('Sugar Shack') were cut into 5 cm cubes and placed in polystyrene containers, sealed, and stored at 2C for 2, 7, or 10 days. At each storage interval, melons were evaluated for drip loss, changes in carotenoid composition, color, soluble solids content (SSC), and titratable acidity. Headspace carbon dioxide and ethylene were monitored during storage intervals. Drip loss after 10 days of storage averaged 13% and 11% for the seeded and seedless melons, respectively. Lycopene content decreased 6 and 11% for 'Summer Flavor 800' and 'Sugar Shack' melons, respectively, after 7 days of storage. Beta carotene and cis lycopene contents were 2 and 6 µg/g and did not change with storage. After 10 days of storage, CIE *L values increased while chroma values decreased, indicating a lightening in color and loss of color saturation in melon pieces. No lesions symptomatic of chilling injury were observed on the minimally processed watermelon after 10 days storage at 2C. Titratable acidity and pH increased, and SSC decreased slightly after storage. Carbon dioxide levels increased and oxygen levels decreased linearly during storage, creating a modified atmosphere of 10 kPa each of CO*2 and O2 after 10 days. Minimally processed watermelon held for 7 or more days had a slight loss of SSC, color saturation, and lycopene.