A novel combination of thermovacuum and thermosonication to inactivate pathogenic bacteria in an Annona muricata L. beverage

Abstract

This work evaluated the bactericidal efficacy of the combination of vacuum pressure plus heat named thermovacuum (TV, alternation of vacuum pressure 33 kPa for 0.5 s during 5 min) and thermosonication (TS, 24 kHz, 80 % amplitude, 0.5 s pulse-cycle) varying the temperature (45–65 °C) and time (10–15 min) against Escherichia coli, Salmonella Paratyphi and Listeria monocytogenes inoculated into an Annona muricata beverage. The bactericidal efficacy was compared between the best TVTS and individual treatments. Lethality, sublethal and morphological injury were evaluated. The best TVTS conditions for the highest microbial inactivation (≥ 7 log CFU/mL) of E. coli and S. paratyphi were 55 °C for 15 min. L. monocytogenes required 65 °C for 15 min for a 5.75 log CFU/mL reduction. Morphological damage was demonstrated. The individual conditions of TVTS were less effective for inactive pathogenic microorganisms. TVTS is a viable technological option for processing A. muricata beverages.

Industrial relevance

This study confirms the importance of combining thermosonication with vacuum pressure to inactive pathogenic bacteria in beverages. The results of the TVTS application are relevant and contribute to a deeper understanding of the mechanism for the inactivation of pathogenic bacteria in fruit beverages, which is essential to food safety. Generating knowledge on microbial inactivation with non-aggressive TVTS technology can lead to further studies that will scale up this combined technology to produce safe food with decreasing operational costs.