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In green plant, volatile aldehydes such as hexanal and hexenal are known to be important‘green’flavor compounds. They are formed from LOX/HPL pathway in the plant. Due to their specific flavour, these aldehydes could be used widely in food industry and cosmetics industry.Linoleic acid ester and linolenic acid ester were used as raw materials in this paper. After saponification, the corresponding fatty acids were generated. The hydroperoxides were synthesized with fatty acid by LOX. Amaranth was used as material of hydroperoxide lyase(HPL). Synthesis of hexanal and hexenal with fatty acid hydroperoxides catalyzed by HPL were studied.It was found that the crude enzyme had a strong adsorption effect on the product which influencing the accuracy of results. On the basis of analytical method’s improvement, the reactions were explored. Univariate experiments on reaction time, temperature, pH, substrate concentration, enzyme amount, BHT concentration, and DTT concentration were taken. On the basis of univariate experiments, orthogonal experiments on substrate concentration, E/S, pH were studied. The optimal condition for producing hexanal was: 20 min reaction time, pH 7.5, 20℃, 35 mmol/L concentration of substrate, 3/35 E/S, 0.5 mmol/L BHT and 15 mmol/L DTT. The yield of hexanal was 2425 mg/L. The optimal condition for producing hexenal was: 10 min reaction time, pH 8.0, 20℃, 40 mmol/L13-HPOT, 3/10 E/S, 1 mmol/L BHT and 15 mmol/L DTT. The yield of hexenal was 1220 mg/L. The yield of hexanal and hexenal could be increased to 2450 mg/L and 1247 mg/L respectively through adding substrate by steps. The volatile products were identified by GC-MS. The products were isolated from the reaction mixture by steam distillation. On this step, the yield of hexanal was about 86.9 %, and the yield of hexenal was about 89.9 %.
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