Microbial growth reduction in tomato juice by pulsed electric field with co-axial treatment chamber

The use of high intensity pulsed electric fields (PEF) in liquid food processing gains popularity as a non-thermal sterilization technology. Both static and co-axial, continuous treatment processes were studied for the non thermal pasteurization of liquid foods (tomato juice) with PEF technology. To determine the number of micro organism present in tomato juice before and after treatment, samples were treated with 30kV/cm and 50kV/cm field intensity with 150 and 300 pulses using continuous PEF treatment chamber. A high voltage impulse generator of 220V/100kV, charging capacitor 50nF and the wave forming network resistance of 22Ω and tail forming resistance of 1200Ω were used to perform this experimental work. After treatment, the samples were stored in air tight glass bottle (75% fill) and the percentage reduction in the growth of microbial content in a treated tomato juice was analyzed for a week. Percentage reduction in the growth of microbial content for the control sample was 72%, compared to 81% and 84% at 30kV/cm and 50kV/cm respectively using 150 pulses. For the same field strength of 50kV /cm, with 150 and 300 pulses, the reductions were 84% and 89% respectively, but with no noticeable reduction in the nutrition contents. These results show that PEF is a promising technology to commercially treat juices in large scale, while maintaining their nutritional values.