Walnut allergy is an increasing concern since allergies to tree nuts and seeds tend to be of an extremely severe nature, causing life-threatening and sometimes fatal reactions. Walnut, Juglans regia, which belongs to the Juglandeceae familily, has a protein fraction of 15%. Many processed foods like cookies, chocolate or bakery products may contain walnut. People allergic to walnut must strictly avoid the consumption of food containing walnut. Cross contamination during the production process often occurs and walnut residues in food cannot be excluded. Therefore sensitive detection methods for walnut in food are required.