Tomato chilling injury threshold defined by the volatile profiles of pink harvested tomato fruit

Fresh tomato fruit show visible symptoms of chilling injury (CI) when stored at temperatures lower than the reported chilling threshold of 12.5°C. However, their sensitivity has been reported to decrease as they ripen. Volatile profiles change during ripening and are affected by physiological changes that occur during storage. Temperature affects the formation of certain volatiles by altering the biochemical processes in the fruit. Volatiles changes could be an indication of the occurrence of CI since it has been shown that the injury starts before the appearance of external symptoms. Many volatile compounds have been reported to contribute to desirable fresh tomato aroma. Others have negative attributes that produce so-called off-flavors. In this study, cultivar Tasti Lee tomatoes at the pink ripeness stage were stored at from 5 to 20°C in 2.5°C intervals. Color and appearance were evaluated every two days as well as homogenized tissue samples being frozen for volatile measurement. Aroma volatiles were analyzed by GC-MS using the SPME headspace method. MHO production was higher above 15°C while it remained lower and at similar levels at lower temperatures. Hexanal production was clustered above and below 12.5°C and geranylacetone production gradually decreased as temperature was reduced. Phenylethanol production was inhibited at temps less than 12.5°C and gradually increased at higher temperatures. This study contributes to further understanding the nature of CI in tomato fruit harvested at a more advanced ripeness stage than is usual for commercial operations. Also, the pattern of changes in the aroma volatile profile that occur in the fruit during low temperature storage can be a good indicator of the actual chilling threshold temperature for tomatoes.