Abstract:

Central composite design combined with response surface analysis was employed to explore interactive effects of pectinase treatment conditions such as treatment time (16－134 min), temperature (20－70 ℃), enzyme dose (0.005%－0.105%) on rheological characteristics of sweet potato slurry. Results showed that both sweet potato slurry with and without pectinase treatment behaved as non-Newtonian, pseudoplastic fluid with yield stress. The correlation between shear rate and shear stress could be well fit using the Herschel-Bulkley model. Sweet potato slurry gradually lost its non-Newtonian characteristics due to pectinase treatment and its apparent viscosity decreased with the increasing of enzyme concentration. A minimum apparent viscosity of 71.56 mPa·s was observed in pectinase-treated sweet potato slurry under the optimal treatment for 70.56 min at 42.34 ℃ with an enzyme dose of 0.1%.

Key words: sweet potato slurry, apparent viscosity, rheological characteristics, pectinase