Effects of heating and recovery media pH on the heat resistance of Alicyclobacillus acidoterrestris Ad 746 spores.

Aims: Alicyclobacillus acidoterrestris is a sporulating, acidophilic bacterial species which spoils acidic beverages such as fruit juices. This work aims to quantify the heat resistance of A. acidoterrestris spores and their recovery potential as a function of heating and recovery media pH.
Methods and Results: The heat treatments were carried out with the strain of A. acidoterrestris Ad 746 in Bacillus acidoterrestris thermophilic medium. The pH of the heating medium from pH 7 to pH 2 nonsignificantly reduced the heat resistance. However, the pH levels of the recovery media strongly affected the apparent heat resistance of this strain. The maximum heat resistance was found when the pH was 4·70 and decreased when the pH decreased to pH 2·8, close to the minimum growth pH and when the recovery medium pH increased to pH 5·3.
Conclusion: The heating medium pH has a slight effect on the spore heat resistances of this acidophilic species. However, the pH of the recovery media strongly affected the apparent heat resistance of this strain.
Significance and Impact of the Study: The obtained parameters quantifying the heat resistance of A. acidoterrestris spores are tools to optimize the heat treatments and to control its development.
(© 2020 The Society for Applied Microbiology.)