ABSTRACT: In order to investigate the effect of pulsed electric field pretreatment on microwave drying equipment of carrot slices, quadratic regression orthogonal combination experiment of four factors (pulse frequency, electric field intensity, microwave power density and slice thickness) was designed with the precipitation rate and rehydration rate per unit time of microwave drying of carrot slices as experimental indexes. The drying rate curve of carrot slices after microwave drying was processed.
The microwave drying kinetics equation and regression equation of each index of carrot slices after pretreatment were obtained by regression analysis with SPSS software, and the indexes were optimized synthetically.
The results showed that the dynamic equation of microwave drying of carrot slices pretreated by pulsed electric field was piecewise applicable to Page model; the effect of pulse frequency and electric field intensity on the precipitation rate per unit time of microwave drying of carrot slices was significant; the effect of pulse frequency on the rehydration rate was significant; the effect of electric field intensity on the rehydration rate was not significant; and the optimal process combination was not significant. The pulse frequency is 30 Hz, the electric field intensity is 2.0 kV/cm, the microwave power density is 1.0 W/g and the slice thickness is 4.0 mm. Under the optimum technological conditions, the precipitation rate per unit time and rehydration rate of carrot slices are improved.
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