Treatment with chlorous acid to inhibit spores of Alicyclobacillus acidoterrestris in aqueous suspension and on apples.

To test the efficacy of a chemical (chlorous acid) for reducing the numbers of viable Alicyclobacillus acidoterrestris spores in laboratory media and on apples. Alicyclobacillus acidoterrestris spores in aqueous suspension and on apple surfaces of four different cultivars were treated with 268 ppm chlorous acid. Treatment with 268 ppm chlorous acid sharply reduced the numbers of spores of A. acidoterrestris in laboratory media by 1.6, 4.3, and 7.0 log(10) reductions for 5, 10, and 15 min treatments, respectively. Chlorous acid also effectively reduced the spore load on apple surfaces. Alicyclobacillus acidoterrestris spore counts were significantly reduced by about 5 log(10) after 10 min treatment on four different apple cultivars ('Red Delicious', 'Golden Delicious',' Gala', and 'Fuji'). There was no synergistic effect on spore reduction when chlorous acid treatment was combined with heat. These results show that chlorous acid is highly efficacious against A. acidoterrestris spores on apple surfaces. Chlorous acid can be used as an alternative sanitizer of chlorine to control a major A. acidoterrestris contamination source in juice processing plants.