Analyzing the major peanut allergens.

Authors: Maleki, Soheila; Schmitt, David; YAMAKI, K. - NAT. FOOD RES. INSTIT.; SHINOHARA, K - National Food Research Institute - Japan; Champagne, Elaine

Submitted to: United States Japan Natural Resources Protein Panel
Publication Type: Proceedings
Publication Acceptance Date: 9/20/2006
Publication Date: 10/21/2006
Citation: Maleki, S.J., Schmitt, D.A., Shinohara, K., Yamaki, K., Champagne, E.T. 2006. Analyzing the major peanut allergens. United States Japan Natural Resources Protein Panel. F3-F8.

Interpretive Summary: It has been suggested that boiling or frying of peanuts leads to less allergenic products than roasting. In this study, we have compared the digestibility of the major peanut allergens in the context of peanuts subjected to boiling, frying, or roasting. Boiled, fried, and roasted peanut proteins were subjected to digestion in a Simulated Gastric Fluid (SGF), and surviving allergenic fragments were using human serum IgE and other antibodies. Previously, it was shown in all three treatments, the major peanut allergens, Ara h 1, and to a lesser extent, Ara h 2, became less soluble with increasing time of exposure to heat, and that IgE binding to insoluble peanut fractions is much higher than to the soluble ones. For ease of analysis, we assessed the susceptibility of the soluble proteins in differently processed peanuts to digestion with SGF. Interestingly, we found that in most cases boiled and raw peanut proteins were similarly digestible, but the Ara h 1 protein in the boiled extracts, was much more resistant to digestion. Most fried and roasted peanut proteins were much more resistant to digestion than in raw and boiled samples. In particular, we found that larger fragments of Ara h 1 were resistant to digestion in fried and roasted samples. In conclusion, the differences in physical properties due to processing, IgE binding, solubility, and digestibility of the major allergens in roasted, fried, and boiled peanuts may not explain some of the discrepancies between the prevalence of peanut allergy in different countries.

Technical Abstract: It has been suggested that boiling or frying of peanuts leads to less allergenic products than roasting. In this study, we have compared the digestibility of the major peanut allergens in the context of peanuts subjected to boiling, frying, or roasting. Boiled, fried, and roasted peanut proteins were subjected to digestion with pepsin in a Simulated Gastric Fluid (SGF), and were then subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and Western Blot analysis using human serum IgE and specific anti-Ara h 1 and Ara h 2 antibodies. Previously, it was shown in all three treatments, the major allergens, Ara h 1, and to a lesser extent, Ara h 2, became less soluble with increasing time of exposure to heat, and that IgE binding to insoluble peanut fractions is much higher than to the soluble ones. For ease of analysis, we assessed the susceptibility of the soluble proteins in differently processed peanuts to digestion with SGF. Interestingly, we found that in most cases boiled and raw peanut proteins were similarly digestible, but the Ara h 1 protein in the boiled extracts was much more resistant to digestion. Most fried and roasted peanut proteins were much more resistant to digestion than in raw and boiled samples. In particular, we found that more high-molecular-weight fragments of Ara h 1 were resistant to pepsin digestion in fried and roasted samples. In conclusion, the differences in physical properties due to processing, IgE binding, solubility, and digestibility of the major allergens in roasted, fried, and boiled peanuts may not explain some of the discrepancies between the prevalence of peanut allergy in different countries.