Egg

Egg allergy is mainly caused by proteins from the egg white, in which ovalbumin is the dominating protein. Other egg white proteins are ovomucoid, ovotransferrin and lysozyme. Lysozyme (E 1105) is also used as preservative during cheese processing.
Allergy to egg yolk proteins also exists, often in combination with allergy to chicken meat.

Egg is common in the following food: bread of different kind, cookies, cakes, meringues, biscuits, pasta, pancakes, mayonnaise, different gravies, meatballs, hamburgers, meat- and fish patés and fish gratins.
Egg might also be an ingredient in cake fillings, cake decoration (icing), ice cream, sorbet, parfait, mousse, puddings, quiche, mashed potatoes, croquettes and liver paté.

Labeling

The presence of egg and products thereof in food products must always be declared, see further in LIVSFS 2004:27 Livsmedelsverkets föreskrifter om märkning och presentation av livsmedel [in Swedish] (see link to the right).

Example of methods of analysis

Sensitive commercial test kits i.e. ELISAs are available for the analysis of egg white proteins. The limit of quantification is about 0,5 mg egg white proteins/kg, somewhat depending on the matrix. 

Egg/egg white proteins can be detected in food samples using rapid methods, based on test strips, which are soaked in an extract of the food or in a swab sample extract. Such tests are only qualitative, i.e. the result is given either as egg/egg white proteins is present (positive) or egg/egg white proteins is not present (not detected) in the food extract. Positive results need sometimes to be confirmed with quantitative methods. It is very important that qualitative test kits don’t give false negative results.

Providers of test kit often have a validation protocol to be submitted with the test kit upon request. Laboratories using commercial test kits must establish in house control of limit of detection and limit of quantification in actual matrices even if the test has been validated by the provider.

Allergic reactions / Doses

The lowest dose of egg white protein that elicitates an allergic reaction is not known. The concentrations of egg white proteins that have been detected in food products causing allergic reactions are listed below.