Allergenic Egg White Proteins in Wine: New Methods Detect Measurable Amounts in Finished Wine

The practice of including warnings about possible food allergens on consumer goods is becoming more commonplace across the globe.  According to the Directive 2003/89/EC in the European Union, all foods that contain traces of a specific list of potential allergens must have a label indicating their presence.  There is similar legislation (in some form or another) in other countries as well, including Australia and the United States.  These labeling laws are placed on hold when the potential allergenic components are used in processes such as winemaking, since there doesn’t appear to be strong scientific data suggesting these allergens are present in the finished product after processing.

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One part of the winemaking process that has the potential to introduce allergens into wine is in the fining process.  The purpose of fining is to remove undesirable phenolic compounds while also reducing bitterness and astringency.  During fining, proteins are added to the wine (i.e. gelatin, milk casein, albumin from egg whites, etc) which then interact with polyphenols and form complexes, which can then be removed via a filtration step or other techniques.  These proteins, particularly eggs, can cause severe allergic reactions in some individuals (0.3% of the adult population), thereby making their presence in wine problematic.  Even with the filtration step, it is not guaranteed that all of the potential allergens will be removed. 

Red wine fining in particular, often employs the use of egg whites (either fresh or in freeze-dried powder form), with doses ranging from 5-15g of fining agent per hL of wine.  Current analytic methods, such as ELISA analysis, do not appear to be particularly sensitive to lower doses of egg white albumin used in the fining process.  Newer methods, such as mass spectrometry, may prove to be more accurate for detecting trace levels of allergens in wine, though the only work done on wine so far using mass spectrometry was using milk proteins and not egg whites.

The purpose of the study reviewed today was to detect egg white proteins in finished red wine using both immunoenzymatic and mass spectrometry techniques.  If either of these techniques is able to find traces of egg white proteins, then the appropriate label should be affixed to the wine in order to avoid any potentially serious allergic reactions by the consumer.

Methods

Egg whites preparations (Albuclar®) were commercially produced and supplied by Enologica Vason S.r.l. in Verona, Italy.

A 2009 vintage Merlot was the wine chosen for the experiment.  As a control, a commercially produced Amarone from a winery in the Valpolicella area in Verona, Italy was used.  This wine was treated commercially using the same Albuclar® egg white preparation as the experimental wine.

Egg white preparations were added to 500mL each of the experimental wines in concentrations of 5, 10, 15, 50, 150, 250, and 300g/hL.  The wine sample treated with 50g/hL of egg white preparation was fined with 50g/hL of bentonite and then filtered on 0.65m in order to test the ability of the absorbent to remove the egg white protein.

For protein detection, gel electrophoresis, dot blot, immunochemical analyses, liquid chromatography and mass spectrometry methods were employed.  For mass spectrometry, only wines with the 5 and 10g/hL doses of egg whites were analyzed.

Results

  •       Protein bands on the electrophoresis gel corresponded to the proteins found in egg whites, all of which are known to be allergenic proteins.
  •        For the immunochemical analysis, egg white proteins were only detected in wines treated with egg whites at doses of 50g/hL or higher.
  •       For the commercial wine supplied by the winery, no egg white proteins could be detected using the immunochemical techniques.
  •       Using mass spectrometry, egg white proteins were found in all of the experimental wines treated with Albuclar®, including the experimental wine treated with the lowest dose (5g/hL).
  •       Using mass spectrometry, egg white proteins were found in both white and red wines.

o   Specific proteins detected by mass spectrometry were ovalbumin, ovotransferrin, lysozyme, and ovomucin.

  •       The mass spectrometry results reveal that it is more sensitive and able to detect egg white proteins in wine where standard immunochemical techniques could not.
  •       Using mass spectrometry, egg white proteins were found in the wine that was treated with bentonite (comparable to the amount found in wines not treated with bentonite).

Conclusions

The results of this brief study indicate that the fining and filtration steps used in winemaking are unable to remove all remnants of egg white proteins from the final wine.  The results also show that standard immunochemical techniques that have been used in the past to determine egg white protein presence lack sensitivity and are inferior to newer techniques such as mass spectrometry.  With mass spectrometry, the scientists were able to find egg white protein in all wines, regardless of the original fining dosage. 

The authors claim they are the first to show that mass spectrometry (combined with liquid chromatography) to detect egg proteins in wines treated with some of the lowest dosages currently used in winemaking fining processes.  These results could have important consequences for the labeling wine with allergenic warnings, which could potentially prevent many adverse allergic reactions for those suffering from egg allergies.

Were you aware that finished wine still contains egg white proteins after processing?  Let me know what you think by commenting below!

Source:  Tolin, S., Pasini, G., Curioni, A., Arrigoni, G., Masi, A., Mainente, F., and Simonato, B. 2012. Mass spectrometry detection of egg proteins in red wines treated with egg white. Food Control 23: 87-94.

DOI: 10.1016.j.foodcont.2011.06.016
I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!

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