Efficacy of ozone against Alicyclobacillus acidoterrestris spores in apple juice

Alicyclobacillus acidoterrestris survives during the typical pasteurization process and can cause the spoilage of fruit juices thanks to its spore forming and thermo-acidophilic nature. In recent years, A. acidoterrestris has become a major concern to the fruit juices industry worldwide. This study was undertaken to evaluate ozone for the reducing number of A. acidoterrestris spores in apple juice. Apple juice inoculated with A. acidoterrestris spores was bubbled with continuous stream of two different constant concentrations (2.8 and 5.3 mg/L) of ozone at 4 and 22 °C up to 40 min. Level of A. acidoterrestris spores in juice decreased by 2.2 and 2.8 log after 40 min of ozonation at 4 °C with concentrations of 2.8 and 5.3 mg/L, respectively. Treatments at 22 °C for 40 min with 2.8 and 5.3 mg/L ozone resulted in 1.8 and 2.4 log reductions of spore viability, respectively. At the ozone concentration of 5.3 mg/L, significant (P < 0.05) reductions were observed in total phenolic content of juice at both temperature levels. However, treatments performed at 2.8 mg/L were observed to have no significant (P > 0.05) effect on total phenolic content. The results presented in this study indicate that over the 2 log reduction in the count of A. acidoterrestris spores in apple juice can be achieved by bubbling ozonation at 4 °C without causing a significant decrease in total phenolic content of product. Therefore, it can be suggested that bubbling ozonation is a promising method for the control of A. acidoterrestris in fruit juices.