P-14 - The Role of Carbon Dioxide and Carbonic Acid in Ensuring Microbial Safety of Non-alcoholic Beer

The demand for non-alcoholic (NA) beer continues to grow, prompting the need for expanded packaging and storage options. However, the absence of ethanol, a key microbial inhibitor, raises concerns about the potential growth of foodborne pathogens. Previous research has demonstrated that Gram-negative bacterial pathogens (i.e., Shiga-toxin producing Escherichia coli (STEC) and Salmonella) grow in unpackaged NA beer at ambient temperature. We hypothesized that the interaction between carbonation level, pH, and undissociated carbonic acid concentration could play a critical role in ensuring the microbial safety of NA beer. There is a lack of data to demonstrate whether these factors provide microbial control in commercial NA beers. This study aims to define these relationships, providing brewers with essential guidelines for maintaining product safety. The objectives of this study were to investigate the effect of carbonation levels, pH, and carbonic acid concentration on Salmonella growth in commercially available NA beers and to identify critical carbonation and pH thresholds necessary to prevent pathogen proliferation during ambient storage. Five commercial NA beer products representing a range of beer styles, carbonation levels, and pH values were analyzed. Non-alcoholic beer styles represented in this work include Belgium, IPA, Kolsch, Stout, Pilsner, Porter, and Wheat. Products were fully carbonated, partially decarbnated, or fully decarbonated. Additional uninoculated samples were held in the same ambient temperature and analyzed at the beginning and end of the ambient storage period (0, 10) for carbonation levels, pH, % ABV, and specific gravity. A Salmonella cocktail was prepared with five strains which were isolated from acidic or mildly acidic environments. The cocktail was diluted to the targeted cell density for this inoculation (~4 log CFU/ml) and samples were stored at 25°C for 10 days. Bacterial enumeration was performed on days 0, 5, and 10 by serial dilution and spread plating onto Tryptic Soy Agar. Increased pH and decreased carbonic acid concentration were associated with higher microbial growth. Salmonella died off in the fully carbonated products during ambient storage. These results suggest that dissolved CO₂ and carbonic acid contribute significantly to NA beer safety. Establishing critical carbonation and pH thresholds will provide brewers with actionable strategies to maintain microbial control, support alternative packaging options, and reduce cold-chain dependency.