Effects of power ultrasound on the activity and structure of β-D-glucosidase with potentially aroma-enhancing capability.

β-d-glucosidase can release aroma precursors to improve the flavor of plant food, but the hydrolysis efficiency of the enzyme is low; the purpose of this study was to improve the enzyme activity using ultrasound. The effects of ultrasound parameters on β-d-glucosidase activity were investigated, and the respective structures of enzyme activated and enzyme inhibited were further analyzed. Low temperature (20-45°C), low ultrasonic intensity (<181.53 W/cm2), and short treatment time (<15 min) led to the activation of β-d-glucosidase, whereas high temperature (45-60°C), high ultrasonic intensity (>181.53 W/cm2), and long treatment time (>15 min) led to its inhibition. Application of ultrasound lowered the optimum temperature for β-d-glucosidase activity from 50 to 40°C. Ultrasound did not change the primary structures of the enzyme, but changed the secondary structures. When ultrasound activated β-d-glucosidase, the α-helix contents were increased, the β-fold and irregular coil content were reduced. When ultrasound inhibited β-d-glucosidase, the contents of β-folds were increased, the α-helix and irregular coil contents were reduced.. In summary, activation or inhibition of β-d-glucosidase under ultrasound was determined by the ultrasound conditions. This study suggests that ultrasound combined with β-D-glucosidase can be used in aroma-enhancing.