EFFECTS OF COMBINATORIAL HURDLES ON A NON-ALCOHOLIC BEER MATRIX CHALLENGED WITH SALMONELLA JAVIANA, ESCHERICHIA COLI, LISTERIA MONOCYTOGENES, PSEUDOMONAS AERUGINOSA, AND BACILLUS CEREUS

As consumer demand for non-alcoholic beer (NAB) grows, producers are moving away from traditional thermal pasteurization to preserve flavor. However, removing ethanol eliminates a key antimicrobial hurdle. This study investigated whether intrinsic factors—specifically pH, carbonation, and antimicrobial additives—can be combined to create a stable, pathogen-resistant matrix for NAB.

The researchers created a model NAB matrix and tested 18 factorial combinations of pH (5.0 or 4.2), carbonation (0, 0.75, or 1.50 volumes CO2), and antimicrobial agents (none, 10 ppm iso-alpha-acids, or 100 ppm potassium sorbate). They also evaluated two alternative strategies: kettle souring and chitosan addition. Each treatment was inoculated with a five-strain cocktail of pathogens (Salmonella Javiana, E. coli O157:H7, Listeria monocytogenes, Pseudomonas aeruginosa, and Bacillus cereus) and monitored over 60 days to track population changes.

• pH is Critical: A pH of 4.2 was significantly more effective than pH 5.0 at inhibiting pathogen growth across all conditions.
• Carbonation Efficacy: Carbonation at 1.50 volumes was essential for controlling Salmonella and E. coli. Lower carbonation levels (0.75 volumes or less) were insufficient to prevent growth in high-pH environments.
• Antimicrobial Synergy: Hop acids (iso-alpha-acids) provided targeted control against Gram-positive bacteria like L. monocytogenes.
• Alternative Strategies: Kettle souring (which naturally lowers pH) was the most effective single treatment, reducing all tested pathogens to below the limit of detection. Chitosan, at the tested concentration, showed limited efficacy.

These findings provide a practical framework for brewers and food safety authorities to design NAB formulations that are intrinsically stable. By optimizing these "hurdles," producers can potentially reduce their reliance on energy-intensive thermal pasteurization while maintaining safety, provided they validate their specific recipe through rigorous challenge studies.