Chilling tomatoes blocks production of flavor-making enzymes

Tomato lovers commonly rant about the suboptimal taste of supermarket varieties. Part of the problem is that most store-bought tomatoes have been bred to slow down softening of the fruit, which makes the tomatoes travel-hardy but also less flavorful. Now researchers are pointing to cold storage—another common feature of the global produce market—as an additional culprit for poor tomato flavor (Proc. Natl. Acad. Sci. USA 2016, DOI: 10.1073/pnas.1613910113). A team led by Harry J. Klee of the University of Florida explored the expression of tomato enzymes that convert lycopene into flavor-imparting volatile compounds. The team found that when tomatoes were stored at temperatures below 12 °C, genes involved in ripening flavor development were methylated, leading to reduced expression of those genes. In parallel, the researchers found that levels of messenger RNA coding for enzymes involved in producing flavor, including those responsible for several consumer-favorite volatiles such as isovaleraldehyde, 3-methyl-1-butanol, and 2-methyl-1-butanol, dropped when tomatoes were chilled.