Influence of Lipid Content and Lipoxygenase on Flavor Volatiles in the Tomato Peel and Flesh

Abstract

: Ten different varieties of tomatoes were separated into peel and flesh and each portion was measured separately. Headspace volatiles were measured in real time using selected ion flow tube mass spectrometry. Lipoxygenase activity was measured using the adsorption of conjugated dienes formed by lipoxygenase. Lipid was extracted and fatty acids were quantified using a gas chromatograph. Volatiles were significantly greater in the peel than flesh when there was a significant difference. The lipoxygenase activity of flesh and peel correlated with the volatiles produced by the lipoxygenase pathway. There was no correlation with other volatiles, which are not dependent on lipid oxidation by lipoxygenase. The lipoxygenase activity, total fatty acid content, and linolenic acid of the peel were greater than the flesh, which is directly related to an increase in fresh, green volatiles. Addition of exogenous lipoxygenase had no effect on lipoxygenase‐derived volatiles formed. The addition of linoleic acid caused an increase in hexanal, 1‐hexanol, and (E)‐2‐heptenal in the flesh and (E)‐2‐heptenal in the peel. Stored unrefrigerated peel had higher volatile concentrations, whereas refrigerated peel had significantly lower concentration than day 0. Storage decreased lipoxygenase activity in the unrefrigerated and refrigerated peel, but had no effect on the fatty acid content. Overall, linolenic acid was the most important to the formation of headspace volatiles, but lipoxygenase activity and unknown factors are also important. Practical Application: The peel of a tomato is most beneficial to the production of volatiles associated with the fresh aroma of tomatoes; therefore, it should be used in the processing of tomato products to produce a fresh, green aroma rather than being removed. Knowledge of the effects of lipoxygenase activity, total fatty acid content, and fatty acid profile on flavor volatiles will allow for better selection of a variety for raw consumption.

Effect of refrigerated storage (12.5°C) on tomato (Solanum lycopersicum) fruit flavor: A biochemical and sensory analysis

“…3E). This behavior is similar to that reported in tomato peel where LOX activity decreased both in refrigerated (2-5 C) and in unrefrigerated (20-23 C) storage (Ties and Barringer, 2012). The decrease in LOX activity during storage suggests that this enzyme is not important in aroma development at this ripening stage, but it might have a role during previous ripening stages.…”

Impact of different large scale pasteurisation technologies and refrigerated storage on the headspace fingerprint of tomato juice

“…This compound, produced via the LOX pathway is one of the key odorant compounds contributing to "green", ethereal and earthy notes in tomatoes (E. A. Baldwin, Goodner, Plotto, Pritchett, & Einstein, 2004;Christensen, Edelenbos, & Kreutzmann, 2007;Ties & Barringer, 2012). Increase of 1-penten-3-one after disruption of tomato tissue was observed by Baldwin et al (2000).…”

Improvement of Flavor and Viscosity in Hot and Cold Break Tomato Juice and Sauce by Peel Removal

“…Typically tomatoes are not peeled prior to being made into juice and it is unknown if the presence of peel during the break process impacts the volatile profile, color, and viscosity of tomato products. Tomato peels produce higher levels of lipid‐derived volatiles than the fleshy part through LOX activity (Ties and Barringer ). The LOX‐derived volatiles include hexanal, ( Z )‐3‐hexenal, ( E) ‐2‐hexenal, hexanol, ( Z) ‐3‐hexenol, and ( E) ‐2‐hexenol, which are typically associated with a fresh green flavor note in tomatoes (Ties and Barringer ).…”