Hurdle approaches using conventional thermal, microwave heating and ginger essential oil in vegetable juice mixture: Heat transfer modeling and microbial inactivation kinetics

In this study, microwave (1000 W; 30 s) and conventional thermal treatments were used in combination with ginger essential oil (EO; 1, 2, 3 % (v/v)) to inactivate Salmonella Typhi and Listeria monocytogenes in a mixture of vegetable (lettuce, spinach, celery, and parsley) juice. The momentum, heat, and Maxwell equations were solved to obtain the electromagnetic and thermal fields simultaneously. Besides, the Weibull model was implemented to simulate microorganisms' inactivation and determine the initiation time and rate. Based on the results, microwave heating with 3% EO reduced the inactivation initiation time by 9.82 and 8.87 s for S. Typhi and L. monocytogenes, respectively (compared to 0 % EO). At the initial stages of heating, where the temperature level has not increased to the desired value, the addition of EO can effectively initiate the inactivation process. The maximum value of resistive losses was reported to be approximately 28 MW/m3. Microwave heating lowered the required process time from 240 to 30 s and 67 % of the consumed power compared to the conventional method. Using microwave and EO in combination can synergistically affect the inactivation of microorganisms.