An enzyme naturally occurring in saliva, tears, nasal and intestinal mucous membranes and also in blood plasma (also muramidase or mucopeptide glucohydrolase), which acts against certain bacteria or microorganisms by breaking down their cell wall and thus destroying them. In the human body it is important for the defence against bacterial infections. Lysozyme is also obtained artificially from chicken egg protein and is used in winemaking, for example in the maceration of red wines. This prevents the reproduction of certain undesirable bacteria. However, the activity of the yeasts (which are immune to lysozyme) is not affected. This means that malolactic fermentation can be avoided at all or can be specifically interrupted at a certain point in time to achieve a desired acidity of the wine.
Lysozyme is also used as an anti-oxidant (antioxidant) to replace or supplement sulphur dioxide. In contrast to the latter, it is more effective especially for must or wines with a high pH-value. It enables an extension of the maceration period, often without the addition of sulphur dioxide. At the very least, it can significantly reduce the amount of sulphur dioxide required to stabilise wines. However, Lysozyme is not effective against Acetobacter (acetic acid bacteria), as these bacteria have a protective membrane over the cell walls. Lysozyme is one of the oenological enzymes. Preparations containing lysozyme are allergens that must be declared if the quantity of proteins in wine exceeds 0.25 mg/l.