Allergen residue testing

The use of fining agents such as Casein, skim milk and egg (whites and albumin) during the winemaking process is commonplace in the wine industry.

The purpose of adding a fining agent preparation to wine is to soften or reduce its astringency and/or bitterness; remove proteins capable of haze formation; or reduce colour by the adsorption and precipitation of polymeric phenols and tannins. The fining agent reacts with wine components either chemically or physically, to form a new complex that can separate from the wine.

Why is it important?

Traces of these fining agents remaining in the finished bottled product can cause allergic reactions in some people, and therefore must be indicated on the label if present when exporting to certain countries.

Unfiltered or filtered wines, non-vintage wines and wines dated 2012 and beyond are required to carry allergen labelling unless they can be demonstrated free of residues.

How do we analyse for these residues?

Our ELISA (Enzyme-linked immunosorbent assay) based test methods comply with the EU requirements of a detection limit (LOD) of 0.25 ppm and a limit of quantitation (LOQ) of 0.5 ppm to prove the absence of these residues.

Egg (Ovomucoid) is one of the main allergens in egg white and appears to be allergenic in minute quantities. We run a double antibody (sandwich) ELISA using specific anti-ovomucoid antibodies coated onto microwells.

Milk (Alpha S Casein) is the major protein in milk and accounts for about 80% of total milk proteins. We run a double antibody (sandwich) ELISA using specific anti-casein antibodies coated onto microwells.

Step 1 The sample is added and if residue is present it will bind to the specific antibodies.
Step 2 Enzyme labeled conjugate is added and binds to the captured residue to form a ‘sandwich’.
Step 3 Substrate is added and forms a blue colour if residue is present. A yellow colour is formed once acid is added to stop the reaction.
Step 4 Results are then read on a micro-plate reader and concentrations determined from the standard curve.
Analysis Volume required Price per sample (ex. GST) Target response time
Total egg white protein residue 10 mL $110 48 hours
Total milk protein residue 10 mL $110
Egg and Milk residue 20 mL $200

How are results reported?

Results < 0.25 ppm are reported as ‘Not Detected’. We report Total egg white protein1 and Total milk protein2 with an uncertainty of measurement of ± 0.1ppm.

11ppm of whole egg powder is equivalent to 0.28ppm of Total egg white protein and ~ 0.14ppm of Ovalbumin.
21ppm of skim milk powder is equivalent to 0.32ppm of Total milk protein and 0.26ppm of Casein.

For further information regarding fining agents for use in the wine industry or maximum residue limits for export destinations, please visit the permitted additives and processing aids webpage or contact commercialservices@awri.com.au.

A printable PDF fact sheet can also be accessed here.

For more information please contact AWRI Commercial Services on (08) 8313 6600 or e-mail commercialservices@awri.com.au