Effect of Temperature on Lipid-Related Volatile Production in Tomato Puree

Abstract

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.

Effect of Enzyme Activity and Frozen Storage on Jalapeño Pepper Volatiles by Selected Ion Flow Tube—Mass Spectrometry

“…Thus, the ratio obtained indicates a higher rate of generation of C6 aldehydes and alcohols from linolenic acid than from linoleic acid in jalapeño peppers. Similarly, a ratio of 3:1 in bell peppers at about 2 h after tissue disruption (Wu and Liou 1986); 2:1 and 5:1 in green and red bell peppers, respectively, at about 1 h after blending (Luning and others 1995a); and 2.5:1 in tomatoes over the 1st 10 min after blending (Xu and Barringer 2009) has been reported. Unlike the (Z) ‐3‐hexenal to (E) ‐2‐hexenal ratio, the ratio of the total amount of unsaturated to saturated C6 aldehydes and alcohols is not considerably affected by time.…”

“…This ratio is extremely time dependent as the concentration of both compounds vary greatly according to their generation/degradation reactions. In grape tomatoes, the (Z) ‐3‐hexenal to (E) ‐2‐hexenal ratio is 1.3:1 over the 1st 10 min after blending (Xu and Barringer 2009). However, at about 1 h after blending the ratio is 1.2:1 and 1:28.5 in green and red bell peppers, respectively (Luning and others 1995a); while at about 2 h after tissue disruption the ratio is 1:34 in bell peppers (Wu and Liou 1986).…”

“…LOX‐derived volatiles are constantly changing to other compounds during the testing period. (Z) ‐3‐Hexenal is converted to (E)‐ 2‐hexenal by Z 3 /E 2 ISO and these aldehydes are reduced to their respective alcohols by ADH (Luning and others 1995a; Xu and Barringer 2009). These changes in the concentrations of the compounds constitute the major cause of the decline over the 10 min.…”

Direct Analysis Mass Spectrometry

“…The effect of chewing and concomitant release of VOCs has also been examined. The application to flavors includes tomatoes [122][123][124], tomatilloes [125], carrots [126], pumpkin seeds [127], jalapenos [128], bell peppers [129,130], strawberries [131], garlic [132,133], cocoa [134,135], almonds [136] and cashews [137].…”

Formation of Volatiles in the Lipoxygenase Pathway as Affected by Fruit Type and Temperature

“…The rate of (Z)-3-hexenal release into the headspace of the fruit purees, which is determined by the rate of volatile generation and volatility, is higher than the rate of degradation and removal while sampling. The concentration of (Z)-3-hexenal then decreased rapidly as its rate of generation became lower than the rate of loss due to isomerization to (E)-2-hexenal, reductive conversion to (Z)-3-hexenol and transformation to hexanal [23,24]. The level of (Z)-3-hexenal may also decrease due to acetal type condensation with the sugars [23].…”