Application of LYSOZYME in wine

The use of lysozyme in wine stops the malolactic fermentation and reduces the dosage of sulphites. It is used in the following way:

1. To delay the malolactic fermentation process (MLF) in red wine

Normally in red wines, the complete malolactic fermentation process is very simple; when the MLF happens quickly it can cause an increase in AV and loss of aroma.

The use of lysozyme in the grape pressing delays the MLF until the end of the alcoholic fermentation process and helps increase the soaking times, even without having added SO2.

This application is interesting for traditional vinifications and for carbonic soaking, especially in grapes of a high pH level where the SO2  is not very effective.

2. To totally or partially block the MLF in white wine

In white wine, when the MLF wants to be delayed or not wanted at all, the lysozyme is used and, as it is not an antioxidant, it has to be used jointly with SO2. The joint use makes possible the reduction of SO2 necessary to block the MLF. Three year testing in processes using lysozyme has proved that the lysozyme allows using between 30 and 40 ppm less of SO2 to block the MLF.

There are recent studies focussed on the use of lysozyme to completely block the MLF in white wine. Although the lysozyme is effective to block the MLF during long periods of time, some wines can eventually complete the MLF. There are a number of reasons that cause this, among them the exact type and population of lactic bacteria, the pH of the wines and the moment of the addition of the lysozyme. The most difficult factor to identify is the resistance of some lactic bacteria to the lysozyme.

3. For wine mixture with complete or partial MLF

When wines that have completed the MLF are mixed with wines that have not completed this fermentation the application of lysozyme reduces the risk of ulterior malic degradation. The death of the lactic bacteria happens in the first few days.

4. For slow fermentation or breaks in fermentation

When the lactic bacteria have consumed the malic acid they can attack the non fermented sugar and cause an increase in AV. This increase of AV, as well as the capability of certain bacteria to compete for the nutrients with the yeasts, is one of the many causes for the slowing down and break up of fermentation. To fight against this problem, in many cases the breaks in fermentation are treated with high levels of SO2.

However, the treatment with SO2 is not effective on some strains of lactic bacteria and, on the other hand, the SO2 is an important factor for the death of yeasts.

The treatment with lysozyme to destroy the lactic bacteria without affecting the yeasts, results much more effective than the treatment with SO2 in complicated fermentations. Also the slowing down and the breaks in the fermentations treated with Lysozyme have lower levels of AV.

5. To stabilise the wine after the MLF

Once the MLF has finished, the population of lactic bacteria can develop undesired aromas and increase the AV. As a standard procedure, SO2 is used in the ageing in the barrel, however, SO2 can complicate the reaction of the tannins and anthocyanins.

The lysozyme does not affect this reaction and the wines treated with lysozyme have more fruit aromas and a more intense colour than those treated with SO2.

It is important to note that the lysozyme does affect neither the Gram negative bacteria nor the yeasts: If the wines contain Acetobacter or Brettanomyces, the joint use of lysozyme with SO2 is necessary.

6. For sparkling wines

The adjuvants used as clarification auxiliaries in the production of sparkling wines contain bentonite that reacts with the proteins responsible for the desired capacity to form bubbles (capacity to produce small bubbles persistently).

In many production trials the sparkling wines treated with lysozyme have a better production of bubbles than those that have not been treated with lysozyme. The bentonite reacts with the lysozyme administered and liberates some of the natural wine protein responsible for these small persisting bubbles.