EFFICIENT GENERATION OF 2E-HEXENAL BY A HYDROPEROXIDE LYASE FROM MUNGBEAN SEEDLINGS

2E-hexenal was generated with a high molar conversion rate by the incu bation of a hydroperoxide lyase containing extract from mung bean seed lings and its substrate, 13-hydroperoxy-9Z,11E,15Z-octadecatrienoic ac id (13-HPOT). Various parameters affected the yield of 2E-hexenal and the conversion rate: hydroperoxide lyase activity was especially, pron ounced in seedlings older than 10 days. The cleavage of 13-HPOT by a s olubilized enzyme extract proceeded best at pH 6.5. Time-course studie s showed that the majority of flavour compounds was already generated during the first 10 min of the incubation period. Using optimized reac tion conditions, a maximum yield of 1062 mg kg(-1) 2E-hexenal was obta ined with 32.6 mmol kg(-1) (10.1 g kg(-1)) 13-HPOT. However, the conve rsion rate was highest (maximum 86.3%) at a low substrate concentratio n, indicating a suicidal behaviour of the hydroperoxide lyase. Enzymat ically hydrolyzed and dioxygenated linseed oil was a suitable alternat ive to pure linolenic acid. (C) 1998 Elsevier Science Ltd. All rights reserved.