Dr. Giuseppe Palmisano and fellow researchers at the University of Southern Denmark, contend that glycoproteins in grapes may be to blame for common allergic reactions to wine, but California grape geneticists caution low-allergen wines are still a long way off.
Newly reported research from European scientists suggesting that the source of allergic reactions to wine may be found in glycoproteins has roused worldwide interest. Genetic scientists in California, however, caution that the results are preliminary: More study is required, and the production of low-allergenic wines is likely a long way off.
“I notice they simply say they ‘look like allergens,’ not that they really are allergens,” commented Dr. Linda Bisson, who studies genetics and microbiology at the University of California, Davis
. Bisson said she had been aware of European groups studying wine allergens. She told Wines & Vines
, though, that she had not yet seen the study claiming that grape glycoproteins are the culprits.
Published in the American Chemical Society’s monthly Journal of Proteome Research
, Dr. Giuseppe Palmisano at the Department of Biochemistry and Molecular Biology, University of Southern Denmark, reported that his team had uncovered 28 grape glycoproteins, some indentified for the first time. Many bear structures that include proteins similar to allergens that trigger reactions to ragweed and latex.
Could fining remove allergens?
In the winemaking process, winemakers can use bentonite, a familiar wine clarifier, to strip proteins from finished wine. This approach is especially effective when combined with a flash pasteurization, high-temperature short-time treatment.
However, Bisson cautioned that before fining, “I would first want confirmation that the proteins were indeed allergenic; changing the structure of a protein slightly can have profound effects. The researchers state SO2
is responsible for the allergen-like reactions, and we know that bacterial amines play a much stronger role.
“Amines trigger headaches in sensitive people—for some, quite severe headaches—but others get more respiratory symptoms. They are made by some species of the lactic acid bacteria,” Bisson said.
She cited another potential culprit, a well-known allergy to yeast proteins, which might also be a factor in reactions to wine. “The yeast allergy appears to be more like a normal allergy from protein/glycoprotein, like peanuts,” and creates more difficulty in breathing. “And some people get an allergic reaction from ethyl acetate, a vinegar compound that is produced by acetic acid bacteria, which is not often found in wine unless it is on its way to vinegar.”
Vine breeding possibility
UC Davis geneticist Dr. Andrew Walker said, “From a breeding perspective, if you identify the glycoproteins or allergenic agents, you could examine winegrapes for varying levels or even test clones of varieties for varying levels. Breeding new varieties with lower or perhaps non-existent levels would be possible.”
Wine chemists and enologists need to research every detail of glycoprotein formation before deciding how to approach breeding for lower glycoprotein levels, Walker stressed. “A survey of grapes and their associated wines would be a good first step.”
How soon could we see low-allergenic wines on the market? According to Walker, “I’d say it will be a while. Depends on knowledge and progress on identifying the sources and causes of glycoprotein development.”
Like Bisson and Walker, UC Davis enology professor and department chair Dr. Andrew Waterhouse
found the study exciting but not definitive. “The results published here only say that they have shown similarity between wine glycoproteins and other known glycoproteins associated with allergic reactions. They did not, for instance, show that wines high in these suspect substances induce more reactions than those without. So, while it is an interesting lead, it does not resolve the question of the importance of the glycoproteins in wine allergenic reactions.”
Clarification from the source
From Denmark, Giuseppe Palmisano further explained the study’s findings. Palmisano and his colleagues believe grape variety and the vinification process influence the amount of glycoproteins in a finished wine.
“Glycoproteins are present in the grape. The N-linked glycoproteins are localized on the cell surface, and play a plethora of functions. They are released during the winemaking process. We do not know yet the qualitative and quantitative difference between the skin and the pulp, but a study of different wines obtained in different winemaking conditions will help in understanding that,” Palmisano explained.
Palmisano acknowledged the need for further research and collaboration with winemakers. “It would be necessary to know the potential of these molecules to elicit an allergenic reaction, and after clinical trials, try to understand which immune responses are activated. We have shed light at the molecular level, but now it is also important to study the potential of these molecules as allergens. It would then be possible to produce ‘low allergenic’ wine (by) removing these substances or changing the glycosylation status, but we have not discussed this with winemakers.”
Next spring, Palmisano and his colleagues hope to publish more findings after further research.
You can read more about the article published in American Chemical Society’s monthly Journal of Proteome Research