Chemical reactions certainly do occcur at different rates at different temperatures, so I don't suppose the precise mechanism really matters to consumers.
Good thing for me that I already prefer my fruit and some beverages at room temp.
Ice-cold watermelon may be refreshing, but it can be less nutritious than watermelon served at room temperature, U.S. Department of Agriculture scientists reported.
Watermelons stored at room temperature deliver more nutrients than refrigerated or freshly picked ones, they wrote in the Journal of Agricultural and Food Chemistry.
The USDA's South Central Agricultural Research Laboratory in Oklahoma looked specifically at carotenoids -- antioxidants that can counter the damage caused by sun, chemicals and day-to-day living. Watermelon is rich in lycopene, an antioxidant that may help prevent heart disease and some cancers.
Compared with freshly picked fruit, watermelon stored at 70 degrees gained up to 40 percent more lycopene and 50 percent to 139 percent extra beta carotene.