EGG ALLERGY
Eggs contain many different proteins that can lead to allergy. Each egg-allergic person is likely to be sensitized to more than one such protein. Someone who has a proven allergy to eggs is usually advised to avoid egg in any form. This is wise in the case of children under the age of 7, because there is a higher risk of a severe or anaphylactic reaction to eggs in this age group. However, for adults, such a risk is much less, and if they have not experienced anything resembling an anaphylactic reaction, it is often useful for them to determine to what degree they need to restrict their intake of eggs. Because there is a great deal of difference between the proteins in egg yolk and the proteins in egg white (the latter tend to be more allergenic than the former), it is sometimes useful to find out which of these egg components is the cause of the allergy so that the diet need not be so restricted. In addition, some egg proteins are destroyed by heat, which means that a person sensitized to heat-labile proteins can consume eggs that are well-cooked, especially in small quantities in baked goods, without any harmful effects. However, a person allergic to heat-stable proteins, which are unaffected by heat, must avoid eggs in any form. So, a discussion of egg allergy should start with a brief description of the different proteins in eggs. Then we can discuss the diet suitable for a person with allergy to any of these components.
Egg Proteins
The white of an egg contains about 10% protein and 80% water. The yolk is made up of 50% water, 34% fat, and 16% protein. Egg white is considered to be the source of the major egg allergens, which include ovalbumin, conalbumin (ovotransferrin), and ovomucoid. Some egg yolk proteins, especially alpha-livetin, may also induce the production of IgE antibodies, and there may be some degree of antigenic cross-reactivity between egg yolk and egg white proteins. Table Egg proteins lists the major egg white and egg yolk proteins that are known to cause allergic reactions in sensitive people.
Table Egg proteins
| Antigenic Egg White Proteins: | Antigenic Egg Yolk Proteins: |
| Major Proteins | Major Proteins |
| Ovalbumin | Lipovitellin |
| Conalbumin (Ovotransferrin) | Phosvitin |
| Ovomucoid | Low-density lipoproteins |
| Ovomucin | Livetins |
| Lysozyme | |
| Trace Amounts of | |
| Catalase | |
| Ovoflavoprotein | |
| Ficin inhibitor | |
| Ovoglycoprotein | |
| G2 and G3 globulins | |
| Ovomacroglobulin | |
| Ribonuclease | |
| Ovoinhibitor | |
| Avidin |
COMPOSITION OF THE AVERAGE CHICKEN EGG
Egg white: 56-61% Yolk: 27-32% Shell: 8-11%
Proteins in eggs from different bird species sometimes cross-react antigenically. However, evidence from a single study indicates that people allergic to duck and goose eggs were not allergic to hen’s eggs. The subject of cross-reactivity between eggs from different bird species needs to be investigated further.
In most cases of egg allergy, IgE antibodies are produced specifically to egg proteins, which differ from the proteins in chicken flesh. However, some livetins are derived from the blood of the hen. IgE antibodies to these proteins might result in allergy to both egg and chicken because blood is sometimes found in the chicken egg.
Although cooking may decompose many of the egg proteins so that cooked eggs may be tolerated in cases where raw egg causes an allergic reaction, some egg proteins, especially ovomucoid, are heat-stable and people who are allergic to this component will react to cooked as well as raw egg.
Avoidance of egg as an individual ingredient in a meal (such as omelette, scrambled, boiled, fried, and so on) is relatively easy. However, eggs are frequently included as an ingredient in prepared foods. As such they may not be so easily recognized unless you take care in reading food labels, becoming familiar with terms that indicate the presence of egg protein, and being aware of the foods traditionally made with eggs.
The Egg-Free Diet
Egg Substitutes
Eggs serve three purposes in recipes:
1. Act as a leavening agent
2. Act as a binder
3. Provide a source of liquid
Substitutes are designed to perform these functions as far as possible, but the finished product may not be exactly the same as when an egg is used.
Substitutes for Egg as a Leavening Agent
1 tbsp egg-free baking powder plus 2 tbsp liquid = 1 egg
Table Terms on labels that indicate the presence of egg
| Albumin | Eggs of all bird
species |
Mayonnaise |
| Ovalbumin | chicken | Simplesse |
| Globulin | duck | Egg powder |
| Ovoglobulin | goose | Egg white |
| Ovomucin | turkey | Egg yolk |
| Ovomucoid | ostrich | Egg protein |
| Ovovitellin | quail | Frozen egg |
| Livetin | plover | Dried egg solids |
| Lysozyme | other | Powdered egg Pasteurized egg gg Beaters™ |
| Nonfood Items that May Contain Egg | ||
| Photographic film | ||
| Printed natural fabrics | ||
| Some fur garments | ||
| Some vaccines are produced from viruses grown in eggs.
The risk of injecting such a vaccine in a highly egg-allergic person should be discussed with his or her physician. |
||
2 tbsp flour plus ½ Tbsp shortening
plus ½ tsp egg-free baking powder =1 egg
plus 2 tbsp liquid
(“Liquid” can be water, vinegar, fruit juice, broth, or any liquid that would be appropriate for the recipe.)
Some recipes call for only 1 egg and a large proportion of baking powder (2 tsp) or baking soda (1 1/2 tsp). Try these recipes without egg and add 1 tbsp of vinegar instead of the egg with the baking powder or baking soda.
Substitutes for Egg as a Binder
Recipe 1
Combine 1/3 cup water and 3 – 4 tsp brown flax seeds. Bring to a boil on high heat, then simmer on low heat for 5 -7 minutes until a slightly thickened gel begins to form. Strain the flax seed out of the liquid and use the gel in the recipes.
This recipe makes enough substitute for one egg. Increase the amounts as needed to substitute for 2, 3, or more eggs.
Some people prefer to leave the flax seeds in the mixture after thickening or to blend them into the gel before using. This may alter the recipe’s taste a little.
Recipe 2
1/3 cup ground flax seed plus 1 cup water
Bring mixture to a boil. Simmer 3 minutes. Refrigerate.
One tablespoon of the mixture replaces one egg.
Recipe 3
1/3 cup extra water plus 1 tbsp arrowroot powder plus 2 tsp guar gum
Recipe 4
2 ounces tofu = 1 egg
Substitutes for Egg as a Liquid
1/3 cup apple juice = 1 egg
OR: 4 tbsp pureed apricot = 1 egg
OR: 1 tbsp vinegar = 1 egg
Commercial egg substitutes can be used (for example, Jolly Joan egg replacer or Egg Replacer marketed by Ener-G-Foods).
DO NOT use Egg Beaters, which is made from egg white.
If egg yolk is tolerated, but egg white causes a adverse reaction, egg yolks separated from the whites can be used, as long as the egg white does not cause an anaphylactic reaction. If the egg white has caused anaphylaxis in the past, do not use egg yolk, because the small amount of albumin that will adhere to the yolk might be enough to cause a reaction.
Egg-Free Baking Powder Recipes
Gluten-Free Baking Powder
| Baking soda | 1 part (1/3 cup) |
| Cream of tartar | 2 parts (2/3 cup) |
| Cornstarch | 1 part (1/3 cup) |
Mix and sift all ingredients together. Use in same quantities as baking powder in recipes.
Corn-Free (Arrowroot) Baking Powder
| Baking soda | part (1/3 cup) |
| Cream of tartar | 2 parts (2/3 cup) |
| Arrowroot starch | 2 parts (2/3cup) |
Mix well and store in an airtight container.
1 tsp regular baking powder = 1 ½ tsp arrowroot baking powder.
Hypoallergenic Baking Powder
| Baking soda | 1 part (1/3 cup) |
| Cream of tartar | 2 parts (2/3 cup) |
| Ground rice (or brown rice flour) | 1 part (1/3 cup) |
Sift all ingredients together thoroughly. Use in same quantities as baking powder in recipes.
This post has been viewed 447 times.