Enzymatic and Chemical Modifications of Food Allergens

Food allergy is defined as an abnormal immunological reaction to food proteins, which causes an adverse clinical reaction. Today 4–6% of children and 1–3% of adults are affected with food allergy in Europe (Mills et al., 2007), while in the USA 6– 8% of children and 4% of adults are affected (Gupta et al., 2008). The incidence of food allergy has been increasing over the years, and to date, no effective treatment of food allergies is available. Therapies involving drugs (antihistamines, decongestants, or steroids) only combat the symptoms of an allergic reaction and do not prevent allergenic reactions due to future exposures to the allergen. Specific immunotherapy (SIT) is the only prophylactic desensitizing therapy for allergy (Bousquet et al., 1998; Durham et al., 1999). However, for food allergies immunotherapy safety-profile is extremely poor because allergic reactions are associated with a significant risk of anaphylactic side-effects (Nelson et al., 1997; Skripak et al., 2008), even with fatal outcome. Therefore, allergen modification resulting in almost complete reduction of IgE-binding, while retaining its immunogenicity, could improve formulations for immunotherapy of food allergies. The best way to prevent unintended exposure to a food allergen is the strict avoidance of foodstuffs containing allergens. Such avoidance may not always be possible, and in certain instances impossible. Furthermore, complete elimination of foodstuffs causing allergy also has negative impact on healthy diet as about 90 % of allergens are present in food of high nutrition value (milk, eggs, fish, shellfish, tree nuts, peanuts, wheat, and soybeans) (Thompson et al., 2006). Therefore production of hypoallergenic food become increasingly indispensable part of food industry with growing demand for methods aimed to reduce allergenic potential of food products. There is increasing number of publications describing successful attempts to reduce allergenicity of food allergens. A number of studies of food processing on allergen reactivity are largely focused on thermal treatments. Although thermal treatments can be used on many products to alter food allergen reactivity, thermal processing has also been known to modify organoleptic properties, including flavor, color, and nutrient content (Holdsworth, 1985). Therefore, novel non-thermal food processing techniques are being explored in order to create hypoallergenic products (Shriver & Yang, 2011). Variable success of methods for allergenicity reduction, due to limited knowledge of allergen and epitope structures and the factors governing their stability, imposes need for an empirical approach (Soler-Rivas & Wichers, 2001). Chemical or enzymatic modification of allergen molecule may alter its structure or physically obstruct binding of IgE antibodies to