Within minutes after ingesting allergenic foodstuffs, IgE-mediated reactions occur in the intestine and patients exhibit vomiting, diarrhea, malabsorption, and blood and protein loss through the intestine. Food allergy is uncommon, affecting approximately 5% of infants and 2% of the adult population.
The major food allergens in the United States and Europe are peanuts, soybeans, tree nuts, milk, eggs, crustacea, fish, and wheat. The allergens may be major (80%) or minor (1%) components of the total plant protein (Table 2). Most food allergens are proteins with a molecular mass between 10 and 70 kDa (Hefle etal., 1996).
Food allergens have unique chemical characteristics that prevent inactiva-tion in the gut. In general, food allergens are stable at temperatures of 100°C for 3 hr over apH range of 2.8 to 10 (Barnett and Howden, 1986). Depending on the nature of enzymatic treatment and the choice of methods for assessing the immu-nogenicity, food allergens are resistant to proteolysis and acid hydrolysis (Taylor, 1995).
In simulated gastric and intestinal models of mammalian digestion, many food allergens are stable for as long as 60 min. The resistance to digestion allows intact antigen to transit from the gut into the mucosa. One exception to this rule is Mactoglobin from cow's milk. This molecule becomes more antigenic following proteolytic digestion (Haddad et al., 1979).
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