Inactivation of Alicyclobacillus acidoterrestris in Orange Juice by High Electric Field Alternating Current

摘要

Alicyclobacillus acidoterrestris spores inoculated in orange juice were inactivated by applying a high electric field alternating current (HEF-AC) to food for a short duration. This new method is effective for inactivating all microorganisms in liquid foods. HEF-AC was compared with a conventional heating method using two oil baths and a tubular heat exchanger for the inactivation of A. acidoterrestris spores in orange juice. Using an HEF-AC pilot plant system at a flow rate of 100L/h, A. acidoterrestris spores in orange juice were exposed to an electric field of 2.5 - 2.7 kV/cm at 20 kHz for 13.8 ms in an electrode unit, as the temperature of orange juice was increased from 35℃ to above 110℃ upon leaving the electrode. Holding times between the electrode and cooling unit varied from 0.3 - 0.9 s. Increasing the holding time of HEF-AC enhanced microbial inactivation, while changing the holding time after the electrode unit was replaced with a tubular heat exchanger had no effect. Comparative studies revealed that the HEF-AC inactivated A. acidoterrestris spores 30 times faster than conventional heating using two oil baths during the holding time.