Developing a new apparatus for inactivating Bacillus subtilis spore in orange juice with a high electric field AC under pressurized conditions

Abstract

An electric inactivating apparatus of micro-organic spores was designed. A continuous AC electric field (20 kHz, 16.3 kV/cm) was applied to orange juice containing Bacillus subtilis spores in order to examine the inactivation effect of electrical equipment. Electrical treatment at 100 °C under atmospheric pressure has a poor ability to inactivate Bacillus subtilis spores. But electrical treatment at 121 °C under pressurized conditions to elevate the boiling point can reduce the viable Bacillus subtilis spores in orange juice four logarithmic orders in <1 s of treatment. 10% of the original ascorbic acid in the orange juice was destroyed after electric treatment. This value compares with 30% that was destroyed by heating in boiling water for 10 min. And the unpalatable flavor of heat-treated Satsuma mandarin juice was not developed in the electric treated juice.