The common existing food allergens are
Peanut flour,
peanut butter, powdered egg white, Powdered/fresh milk Soy milk, soy flour Wheat breads, flour etc.
As allergic reactions are IgE mediated, blood tests will show increase in these levels secondary to a food allergy. The problem with the food allergy testing is sometimes the amount of food they challenge with may be not sufficient to elicit any allergic reactions.