Mustard belongs to the Brassica plant family. With about 30-35% the fraction of proteins in mustard seed is very high. Some of these proteins are known for being allergenic, such as Sin a 1 and Bra j 1. These proteins are predominantly heat resistant making them stable to different production processes. In addition to brown mustard (Brassica juncea) and black mustard (Brassica nigra) primarily yellow mustard (Sinapsis alba) is used as an ingredient in many foods and food preparations. For mustard allergic persons hidden mustard allergens in food are a critical problem. Already very low amounts of mustard can cause allergic reactions, which may lead to anaphylactic shock in severe cases. Because of this, mustard allergic persons must strictly avoid the consumption of mustard or mustard containing food. Cross-contamination, mostly in consequence of the production process, is often noticed. The sau-sage production process is a repre-sentative ex-ample. This explains why in many cases the