Fresh tomato specific fluctuations in the composition of lipoxygenase-generated C6 aldehydes

Linoleoyl and alpha-linolenoyl fatty acyl groups are converted to hexanal a nd hexenal ((Z)-3-hexenal and (E)-2-hexenal), respectively, on the macerati on of tomato fruits. These C6 aldehydes greatly contribute to the mix of vo latile compounds which determines the flavour of the tomato. Cherry and sta ndard fresh tomatoes were used to study the relationship between fatty acid composition of the intact fruit and the C6 aldehydes produced on maceratio n. The cherry tomato (var. Cherry Belie) had approximately twice as much ct -linolenic acid as the standard tomato (var. Solairo). The enrichment of a- linolenic acid in the cherry tomato compared to the standard tomato was not evenly distributed between the major lipid classes (neutral lipids, glycol ipids and phospholipids) but was prominent in the neutral fraction. The lin oleic/alpha-linolenic acid ratio in the cherry and standard tomatoes was 1. 75 and 4.1, respectively; this was reflected but not matched by the hexanal /hexenal ratio on macerating these tomatoes (0.1 and 0.27, respectively). A nalysis of volatile compounds on macerating tomato fruits was extended to 1 4 other commercially available varieties which were nominally split into 'c herry' (50 g average fruit weight and below) and 'standard' (average fruit weight above 50 g) tomatoes. Hexanal/hexenal ratios were remarkably differe nt between 'cherry' (0.05-0.1) and 'standard' (0.14-0.27) tomatoes. The con cept of increasing a-linolenic acid levers in tomatoes to increase desirabl e flavour is discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.