Effect of temperature on lipid-related volatile production in tomato puree

Lipid-related volatiles were measured in real time after the blending of grape tomatoes, using selected ion flow tube mass spectrometry (SIFT-MS). Measurements were made at 4, 23, or 37 degrees C. The volatiles in the headspace of the tomatoes, other than hexanal, increased with increasing temperature. The concentration of hexanal in the headspace increased from 4 to 23 degrees C, but decreased at 37 degrees C. The activity of hexanal-specific hydroperoxide lyase decreases at 37 degrees C. Moreover, precursors of hexanal may go through alternative pathways to form trans-2-heptenal and trans-2-octenal. The increase in concentration in the headspace for most volatiles can be explained by the increase in volatility, except for trans-2-heptenal, trans-2-octenal, and trans-2-pentenal. These three volatiles appear to be generated at a much higher rate at 37 degrees C due to the dominance of alternate pathways at this temperature. Temperature did not affect the time to peak level for most volatiles, except the time for hexanal was shorter with increasing temperature. A temperature-dependent lipoxygenase pathway was postulated.