Volatile Compounds in Flavor Concentrates Produced from Crayfish-Processing Byproducts with and without Protease Treatment

Crayfish-processing byproducts (CPBs) were hydrolyzed using alkaline protease Optimase APL-440 under optimum conditions. Volatile components of flavor concentrates prepared by atmospheric evaporation (100 °C) and vacuum evaporation (60 °C) were analyzed and compared by gas chromatography/mass spectrometry and gas chromatography/olfactometry. Concentrations of 12 pyrazines in flavor concentrates increased significantly ( p < 0.05) after enzymatic hydrolysis. Concentrations of dimethyl disulfide, dimethyl trisulfide, and benzaldehyde also increased after enzymatic hydrolysis, whereas lipid decomposition products decreased significantly. Levels of thermally generated volatiles were much higher after atmospheric evaporation. A greater number of aroma-active compounds were detected in CPB hydrolysates than in unhydrolyzed CPBs.