Effects of Lysozyme on the Microbiological Stability and Organoleptic Properties of Unpasteurized Beer.

Lysozyme is an antimicrobial enzyme that could be applied to counteract those bacterial species which, due to their own metabolic activity, possess notable beer spoilage ability and lead to loss of beer quality. Experiments were carried out to assess lysozyme potential to prevent the growth of beer spoilage bacteria, and to verify the effect of lysozyme on the microbiological stability and sensory characteristics of unpasteurized beer. Eight replicates, all from the same lot of Italian beer, were treated with 0 and 100 ppm lysozyme. Microbiological analyses were conducted bimonthly to investigate the presence of spoilage bacteria. Sensory analyses were performed to determine whether there were any significant differences in sensory impressions between beers produced with and without lysozyme. Lysozyme exerted a strong inhibitory action on the lactic acid bacteria (LAB) present in the beer and was very stable throughout the shelf life. Sensory tests revealed no unfavourable influence on beer flavour when using lysozyme. Indeed, the shelf life of beer with added lysozyme proved to be extended. Even as late as 1 month after the expiry date it still met with the panellists' approval. Lysozyme may be regarded as an effective agent for preventing microbiological contamination and prolonging the stability of unpasteurized beer.