The Influence of the Presence of Wheat Flour on the Antigenic Activities of Egg White Proteins

Abstract

Purpose: It is known that ovomucoid, an egg allergen, is heat resistant and remains soluble after heating. However, a recent study showed that the antigenic activity of ovomucoid could be reduced by heating when egg white (EW) was mixed with wheat flour. This study was performed to determine the influence of wheat flour on the antigenic activities of EW proteins when EW is heated, and the influence of the duration of heat treatment. Methods: A mixture of EW and wheat flour was kneaded for 10 minutes and then baked at 180 degrees C for 10 minutes and 30 minutes. The EW without wheat flour was also heated at 180 degrees C for 10 minutes and 30 minutes. The proteins were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and IgE immunoblotting was performed with the pooled sera of 5 egg-allergic patients. The antigenic activities of ovomucoid in different EW samples were measured by inhibition enzyme-linked immunosorbent assay (ELISA). Results: 1) SDS-PAGE: the intensity of the 37-50 kD bands (overlapped bands of ovomucoid and ovalbumin) decreased significantly in the mixture of EW and wheat flour baked for 30 minutes, compared with the mixture baked for 10 minutes, heated EW and raw EW. 2) IgE immunoblot: in the mixture of EW and wheat, a remarkable decrease of IgE reactivity to 37-50 kD was observed when baked for 30 minutes. 3) Inhibition ELISA: the antigenic activity of ovomucoid decreased significantly in the mixture of EW and wheat baked for 30 minutes, but not in the heated pure EW. Conclusions: This study showed that the antigenic activity of ovomucoid can be reduced by baking EW with wheat flour. The decrease in ovomucoid antigenicity in the baked mixture of EW and wheat flour was dependent on the time of heat treatment, indicating that heating should be prolonged to achieve a reduction in ovomucoid antigenic activity.