Suppression of volatile production in tomato fruit exposed to chilling temperature and alleviation of chilling injury by a pre-chilling heat treatment

- A short chilling exposure of tomatoes at mature green stage caused flavour loss.
- Heat treatment at mature green stage did not affect volatile levels after ripening.
- A pre-chilling heat treatment alleviated reduction of some key volatile compounds.
- Sensory panels recognized the flavour improvement of pre-chilling heat treatment.

Chilling exposure of tomato fruit to 5 °C for less than 5 days at mature green stage does not cause visual symptom of chilling injury (CI), however, it is unknown whether such conditions would impact flavour quality (internal CI) after ripening, and if a pre-chilling heat treatment could alleviate internal CI. In this experiment, mature green 'FL 47' tomatoes were gassed with ethylene to initiate ripening before heating and/or chilling treatment, and fruits were ripened at 20 °C after short exposure to the high or low temperature. Volatile analysis of the fruits were conducted after ripening. Chilling treatment generally suppressed production of aldehyde, alcohol, ketone, ester, acid and terpene volatile compounds, including the following abundant and/or important volatiles: hexanal, trans-2-hexenal, 6-methyl-5-hepten-2-one, β-ionone, 2-methylbutanal, 2-phenylethanol, guaiacol and 2-isobutylthiazole. Heat treatment alone did not affect most volatile levels after ripening. Heat treatment prior to chilling exposure alleviated the reduction of some key volatile compounds caused by chilling exposure, which agreed with sensory panel results in that panellists perceived more tomato flavour in “heating + chilling” treated fruit than fruit that were chilled only.