Effects of Heat Pump Drying Parameters on the Volatile Flavor Compounds in Silver Carp

Abstract

ABSTRACTEffects of various heat pump drying parameters (temperature, air velocity, bypass air ratio, and drying time) on the volatile compounds in silver carp (Hypophthalmichthys molitrix) were studied. These parameters determined the drying rate and influenced the formation of the volatile flavor compounds. High temperatures strongly promoted the volatile flavor compounds’ formation. Temperature increase from 5 to 35°C induced increase in the total various volatile compounds (including alcohols, aldehydes, ketones, and acids) content, total volatile basic nitrogen (TVB-N), and thiobarbituric acid-reactive substances (TBARS). However, high temperatures (> 35°C) led to many unpleasant volatile odors. Increase in the air velocity (0.35–1.65 m s−1) and bypass ratio (0.2:1.0) led to increases in the volatile compound contents but decreases in the TVB-N and TBARS values. The TVB-N content was the lowest in all the samples when the bypass air ratio value was 0.6. The drying time had negative effects both on the generation of volatile flavor compounds and TVB-N and TBARS. We found that the optimal temperature, velocity, bypass ratio, and time for our process were 20°C, 1.65 m s−1, 0.6, and 36 h, respectively.