OREGON STATE UNIVERSITY

ENZYME SHOWS PROMISE AS WINE-MAKING TOOL

07/30/1996

CORVALLIS - Does wine go with egg whites? Maybe.

Lysozyme, an enzyme found in egg whites, shows promise as a tool for preserving and stabilizing many wines, says an Oregon State University researcher.

Substances called sulfites, added to wine as sulfur dioxide, currently perform these functions. But a small percentage of people are allergic to them. Wine labeling regulations require that a sulfite warning be on bottles containing more than 10 parts per million, which means the warnings are on most wine bottles.

"Sulfites are added for two reasons. They eliminate spoilage microorganisms and protect wine from oxidation reactions that can cause off colors and flavors," said Mark Daeschel, a microbiologist in OSU's Department of Food Science and Technology.

In his lab, Daeschel is studying how lysozyme kills some undesirable spoilage bacteria, including types that produce substances called biogenic amines that can give some people who drink wine headaches, nasal congestion, hives and itching. Daeschel hopes lysozyme also will give wine makers an option for lowering the amount of sulfur dioxide they use.

However, the enzyme isn't going to get rid of all sulfites in wines in the foreseeable future, predicts Barney Watson, an OSU Extension Service enologist or wine-making specialist. Yeast used to ferment wine produce low levels of sulfites naturally, he said, and it is necessary to add sulfur dioxide to wines to prevent undesirable oxidation.

But lysozyme does show potential for allowing wineries to add sulfur dioxide after yeast fermentation rather than before, as some wine makers prefer to do now, according to Watson. He explains that some wine makers prefer "spontaneous" fermentation's because they think it adds complexity to the wine. So they add little or no sulfur dioxide before fermentation to encourage growth of "wild" yeast present on the fruit, rather adding commercial yeast cultures to start fermentation.

Lysozyme also may be useful in inhibiting undesirable secondary bacterial fermentation, and in stabilizing wine after desirable bacterial fermentation, said Watson. Another potential use is the addition of lysozyme to help prevent spoilage in the few "organic" wines that have no added sulfites.

"The trend in the wine industry, based on consumer preference, is for minimal processing," said Daeschel. "This means using less filtration (which removes suspended particles in the wine) and finding ways to use less sulfites."

Though lysozyme is extracted from egg whites, all of the constituents of the egg that are a problem for people with egg allergies are removed, noted Daeschel.