The enzymic breakdown of lipids to volatile and non‐volatile carbonyl fragments in disrupted tomato fruits

Physical disruption of tomato fruits results in the degradation of endogenous lipids by hydrolytic and oxidative enzymes. Acyl hydrolase, phospholipase D, lipoxygenase and hydroperoxide cleavage enzymes are active in this tissue. A sequential enzymic pathway is proposed by which tissue lipids are hydrolysed to free (mainly polyunsaturated C18) fatty acids which are subsequently oxidised to their hydroperoxides by lipoxygenase action. The C18 hydroperoxides are cleaved (by an enzyme which is specific for 13‐hydroperoxide isomers) to volatile C6 aldehydes (hexanal or cis‐3 hexenal) and non‐volatile C12 w‐oxoacids. The non‐volatile fragment from linoleic acid was identified as 12‐oxo‐dodec‐cis 9‐enoic acid.