Analyses of allergens in wine to establish the impact of filtration and fining of wine
It is important for the South African wine industry to be informed regarding the levels of allergens remaining in the final bottled wine, after normal fining techniques and filtration processes have been applied. This will enable winemakers to make an informed decision whether to label for allergens, without having to analyse each batch of wine for each type of allergen. The sample set used in the study was based on actual wine being made in real time in order to assess the effect of filtration on the allergen concentration of the final wine. The principle of good manufacturing practice applied to the dosage of allergens; therefore only the amount that was needed, was added. No experimental samples were used during the study and a sliding scale of dosage was therefore not possible. The objective was to determine whether allergen labelling would still be necessary if the correct filter size was used during filtration to remove residual allergens.
The determination of allergenic fining agent protein residues in wines were done using the ELISA method, which is based on a basic microtiter plate spectrophotometer. Rida®Soft Win software was used to interpret and document the results.
In the samples set almost all wines were fined using the following type of proteins: ovalbumin (egg white), casein and gelatin. Very few producers added Lysozyme to their wines. The study focused on the analyses of allergens: ovalbumin, casein and lysozyme. Gelatin was not part of the study, as it is not an allergen. The main dosage of fining agent used by producers was between 2 and 3 g/Hl of wine. All wines were fined between 3 and 11 days after production. All wines that were analyzed directly after fining, but before filtration, showed the presence of allergens at different concentrations, except for one wine. However, all wines that were positive for the presence of allergens showed that no allergens could be detected after the wine was filtered. The size of the filters that were used for filtration was between 0.2 and 0.65µl.
All wines that tested positive for the presence of allergens after fining, tested negative for the presence of allergens after filtration, suggesting that filtration, using the correct filter size, could indeed remove all residual allergens from the wine and therefore negate the need to label or test for allergens and therefore save cost.