Efficient generation of 2E-hexenal by a hydroperoxide lyase from mung bean seedlings

2E-hexenal was generated with a high molar conversion rate by the incubation of a hydroperoxide lyase containing extract from mung bean seedlings and its substrate, 13-hydroperoxy-9Z, 11E, 15Z-octadecatrienoic acid (13-HPOT). Various parameters affected the yield of 2E-hexenal and the conversion rate: hydroperoxide lyase activity was especially, pronounced in seedlings older than 10 days. The cleavage of 13-HPOT by a solubilized enzyme extract proceeded best at pH 6.5. Time-course studies showed that the majority of flavour compounds was already generated during the first 10 min of the incubation period. Using optimized reaction conditions, a maximum yield of 1062 mg kg−1 2E-hexenal was obtained with 32.6 mmol kg−1 (10.1 g kg−1) 13-HPOT. However, the conversion rate was highest (maximum 86.3%) at a low substrate concentration, indicating a suicidal behaviour of the hydroperoxide lyase. Enzymatically hydrolyzed and dioxygenated linseed oil was a suitable alternative to pure linolenic acid.