Evaluation of the behavior of Alicyclobacillus acidocaldarius and related species in acidic beverages

The behavior of Alicyclobacillus acidocaldarius and related species, isolated from food manufacturing environments and food ingredients, in acidic beverages was investigated. These bacteria are frequently detected in the raw materials of beverages. A. acidocaldarius and related species grew at temperatures between 40 and 55°C in beverages with an osmotic pressure from 250 to 300 mOsm, so-called isotonic drinks. Ascorbic acid at 350 mg/L inhibited growth, likely due to ascorbic acid.s consumption of dissolved oxygen in the isotonic drinks. In contrast, bacterial growth was observed in the absence of ascorbic acid. No bacterial growth was detected in fruit drinks with an osmotic pressure of 700mOsm in the absence of 350 mg/L ascorbic acid. Bacterial growth resulted in an off-odor and flavor deterioration of the drinks. Bacterial growth was promoted by the addition of 0.1% fruit juice in a glucose solution at 700 mOsm. Moreover, the bacteria grew well even in the presence of 500 mg/L ascorbic acid in a hypotonic drink with an osmotic pressure of 200 mOsm. Our results suggest that A. acidocaldarius and related species are potential spoilage bacteria of acidic beverages, especially so-called hypotonic drinks. Therefore, bacterial decontamination using a membrane filter during the manufacturing process of acidic beverages is necessary. Further, detailed analysis of the beverage ingredients is important to control bacterial growth in acidic beverages.