Decrease in Antigenic and Allergenic Potentials of Ovomucoid by Heating in the Presence of Wheat Flour:  Dependence on Wheat Variety and Intermolecular Disulfide Bridges

Abstract

The antigenic and allergenic activities of ovomucoid (OM) remaining in soluble fractions of pasta-like model samples of wheat flour mixed with egg white were investigated by ELISA competitive inhibition and immunoblotting analyses using a rabbit anti-OM IgG and the serum IgE specific for OM in patients allergic to egg white. The mixture of egg white and wheat flour of soft, hard, and durum varieties was kneaded for 10-50 min and benched for 1 h at RT, and then small pieces of the dough were heated in boiling 1% NaCl solution for 15 min. Even before heating, only after the kneading for 30 min or more, but not after kneading for only 20 min, followed by the benching, the antigenic activity of OM which remained in the phosphate-buffered saline extract from the dough markedly decreased. Almost no antigenic activity of OM was detected in the extracts of heated samples. Furthermore, in the extracts of heated durum samples, only a trace of or almost no IgE-reactive OM was detected against the five patients' sera. These reductive effects of wheat on the OM antigenicity and allergenicity were more remarkable in the durum variety than in the others. No detectable proteins were extracted with 1% SDS from the heated samples, whereas OM was extracted with 1% SDS containing 10% 2-mercaptoethanol, suggesting heat-induced polymerization through intermolecular disulfide bonds among OM and wheat.

Recognition of Native and/or Thermally Induced Denatured Forms of the Major Food Allergen, Ovomucoid, by Human IgE and Mouse Monoclonal IgG Antibodies

“…It is notable that the aggregate was stable, even after boiling for 5 min in the presence of 5% -mercaptoethanol and 2% SDS. Although Kato et al have reported reductive allergenicity for the aggregates of OM with wheat proteins, 28) the allergenicity of those described here is unknown. If mAb 7D is used instead of mAb 6H, the carbohydrate moiety-specific or hen's OM-specific profile could be obtained.…”

Towards a Comprehensive Validation of ELISA Kits for Food Allergens: Case 1—Egg

“…Most of the protein stability studies have been performed on purified proteins, and limited information exists on the stability of food proteins in food matrices after processing. Although ovomucoid has been reported to be resistant to heat, a study assessing the stability of ovomucoid in wheat flour suggests that heatinduced polymerization renders the allergen unextractable using traditional extractions solutions (Kato et al 2001). It is important to be aware that validation parameters are, in some cases, affected by the combination of several factors.…”

Nanotechnology and Food Allergy

“…The ability of wheat prolamins to form disulfi de bonds could alter the allergenic properties of other ingredients in baked goods, and it has been shown that the egg white allergen ovomucoid becomes disulfi de -linked to the gluten proteins during baking, rendering it insoluble and hence reducing the allergenic activity of soluble extracts made from such baked goods [64] . Alternatively, this loss of IgE reactivity might be due to leaching of the allergen into the cooking water, as has been observed for another prolamin superfamily member, the peanut allergen Ara h 2 [65] .…”