Background Increased allergenicity of roasted vs. raw peanut has been reported by showing higher IgE binding to roasted peanut extracts.
Objective To study the effect of roasting on Ara h 1 quantification in peanut using a specific monoclonal antibody-based ELISA, and to compare the Ara h 1 content from different kernel size peanuts from four runner cultivars.
Methods Raw or oven-roasted (177°C for 5–30 min) runner peanuts were crushed and extracted at 60°C. Inhibition ELISA was used to study binding of Ara h 1 purified from raw or roasted peanut. Runner peanuts of four different cultivars were collected, shelled, sized and roasted for 15 min at 177°C. Ara h 1 in the extracts was compared by ELISA.
Results Ara h 1 levels were up to 22-fold higher in roasted than in raw peanuts (820 vs. 37 μg/mL, in a representative experiment) with an Ara h 1 peak at 10–15 min of roasting. Inhibition ELISA indicated that this increase was not due to conformational changes in the Ara h 1 monoclonal antibody epitopes. Ara h 1 was found at lower levels in number 1 than in jumbo- and medium-sized peanuts, and no differences were found among cultivars.
Conclusion These results suggest that roasting increases the efficiency of Ara h 1 extraction, and/or that the monoclonal antibody binding epitopes were more accessible in roasted peanut. Expression of Ara h 1 is associated with peanut maturity.