Application of the Enzyme Lysozyme in Brewing

Mark A. Daeschel, L. Bruslind and J. Clawson.

Abstract
Hen lysozyme is a naturally occurr ing enzyme which is obtained by simple extraction from egg whites. Lysozyme exerts an antimicrobial effect against Gram positive bacteria by hydrolyzing the ( (1-4) linkages within the peptidoglycan layers of the cell wall. It is not active against eukaryotic cells including yeast and mold. Several applications for lysozyme as an antimicrobial agent in beer have been developed. The addition of lysozyme (100 or 200 ppm) to harvested yeast destined for reuse was effective in eliminating some, but not all, intentionally introduced strains of lactic acid bacteria. Additionally, lysozyme was effective in inhibiting lactic acid bacteria added to finished beers. Lysozyme had no significant effects on foam stability (sigma). Lysozyme when added to beer retained greater than 60% of its initial activity (either 50, 100, 150, 200, 250, 300 or 400 ppm) after 6 months storage at either room temperature or under refrigeration. Chill haze was evident in beers containing 300 ppm or greater of lysozyme. A duo-trio consumer (n=90) sensory evaluation on commercial beers (American light lager and porter) spiked with either 100 or 300 ppm failed to indicate significant differences from the unspiked control.
Keywords: lysozyme, antibacterial, bactericidal  

Sintesis
Hen lysozyme es una encima natural que se obtiene por la simple extraccion de clara de huevo. La lysozyme excerta un efecto antimicrobial contra bacteria Gram positiva al hidrolizar los lazos ( (1-4) dentro de las capas peptodiclanes de la pared de la celula. No es activa contra celulas eucraioticas incluyendo levadura y moho. Se ban desarrollado varias aplicaciones para lysozyme como un agente antimicrobial en la cerveza. La adicion de lysozyme (100 o 200ppm) a levadura cosechada destinada a reuso fue efectiva en eliminar algunas, pero, no todas, intencionalmente introducidas cepas de bacteria lacto acida. Adicionalmente, lysozyme fue efectivo en inhibir bacteria lacto acida adicionada a cerveza terminada. Lysozyme no tuvo efectos significativos en la estabilidad de la espuma (sigma). Lysozyme al ser ahadido a la cerveza retuvo mas del 60% de su actividad original (sea en 50, 100, 150, 200, 250, 300 o 400 ppm) despues de 6 meses de almacenaje sea a temperatura. ambiental o en refrigeracion. Turbide fue evidente en cervezas con que contenian mas de 300ppm de Lysozyme. Una evaluacion sensorial de consumidor duo?trio (n=90) en cervezas comerciales (lager suaves y porters americanas) adicionadas con sea 100 o 300 ppm no pudieron indicar diferencias significativas del control sin adicion.