How chilling leaches flavor from tomatoes

How chilling leaches flavor from tomatoes

Chilling fruits at temperatures below 12 °C hampers enzymes that help synthesize flavor-imparting volatile compounds, resulting in relatively fresh but insipid fruits. To uncover the genetic underpinnings of chilling-associated flavor loss, researchers  stored heirloom and modern inbred varieties of red ripe tomatoes at 5 °C for 1, 3, or 7 days after which the fruits were transferred to 20 °C for 1 or 3 days.

Measurement of volatile compounds revealed that 7 days of cold exposure reduced volatile levels by up to 65%; 3 days of recovery at the higher temperature failed to restore volatiles to normal levels.

A panel of 76 consumers judged fruits stored at 20 °C after 7 days of chilling much less flavorful than fruits harvested a day before consumption. Though the fruits’ sugar and acid contents remained largely unaltered, chilling reduced the expression of genes implicated in volatile synthesis as well as the gene switch RIPENING INHIBITOR (RIN), the epigenetic action of which is tied to fruit ripening, among other switches.

Analysis of rates of methylation of cytosine residues in the control regions of RIN-dependent genes suggested a link between chilling and DNA methylation of genes implicated in volatile synthesis and fruit maturation.

According to the authors, the findings furnish a molecular view of the flavor-depleting effects of cold storage on fruits.