Aims: The aim of this study was a challenge testing the effect of lower concentrations of micronized benzoic acid against two strains of Alicyclobacillus. Methods and Results: The effect of micronized benzoic acid was compared with the usual levels of untreated commercial sodium benzoate and benzoic acid, at the challenge temperature of 45 degrees C. The size of the benzoic acid particles was determined by scanning electron microscopy. The diameter of the micronized particles was around 10m with a maximum length of 200m, while the untreated preservative structures were irregular with lengths up to 500m. A continuous bactericidal effect against two Alicyclobacillus strains, throughout the 28-day period, was observed with 50mgl(-1) of micronized benzoic acid, but when the untreated preservative was used, the same lethal effect was not achieved even after doubling its concentration. Conclusions: The antimicrobial activity of benzoic acid was improved by micronization. The process proved to be an effective alternative to reduce the benzoic acid concentration necessary to ensure stability of an orange juice matrix. Significance and Impact of the Study: The results proved that the micronization process represents an alternative to reduce the required food preservative concentration; this method increased the stability of the compound, which maintains its bioavailability.