Influence of electrical process parameters to inactivate microorganisms in orange juice by PEF technology

Abstract

Pulsed electric field (PEF) is a non-thermal/chemical food processing method for microbial inactivation in liquid food. This method finds its application to prolong the shelf-life of the seasonal fruit juices which helps to maintain the supply chain throughout the year. So, in the present study, the most commonly found microorganisms of Escherichia coli (E. coli), Staphylococcus aureus (S.aureus) and Saccharomyces cerevisiae (S.cerevisiae) inoculated in orange juice are considered. PEF impact on microbial inactivation based on the experimental results are analyzed with respect to pulse frequency, electric field intensity and treatment time. The PEF treatment conditions set for the investigation are as follows. Electric field intensity: - 5 kV/cm and 10 kV/cm; Pulse frequency: - 1, 10, 20 and 50 kHz; Pulse width: - 1.2 µs; Treatment time: - 10 s, 20 s, 30 s, 40s and 50s. A maximum inactivation of log10 reduction 2.62 ± 0.122 is observed when E. coli was subjected to 10 kV/cm at 50 kHz. Meanwhile S.cerevisiae and S.aureus are inactivated at the level of log10 reduction 2.4 + 0.16 and 2.1 + 0.9 respectively at the same treatment conditions when the treatment time is 50 s. It is also observed that the electric field intensity along the higher frequency enhances the inactivation level of microorganisms and the variations in the log reduction might be due to the different biological structure of the microorganisms.