Citric acid pretreatment for suppressing adhesion of major egg allergens to a stainless steel surface

Adhesion of proteins to solid surfaces can cause a number of problems in food manufacturing. In particular, a tiny amount of adherent allergenic proteins may pose a cross-contamination risk. To explore a strategy for suppressing adhesion of major egg allergens to stainless steel surfaces, the effect of citric acid pretreatment of stainless steel surfaces on the adhesion of ovalbumin and ovomucoid was studied under various conditions. Stainless steel powder was subjected to adhesion experiments after treatment with 50 mM citric acid solution, rinsing with water, and drying. Results from ovalbumin adhesion at 30 °C and pH 7.4 demonstrate that citric acid was more effective against ovalbumin adhesion than any univalent or divalent organic acid tested. This supports the idea that the suppression of adhesion is ascribed to the acid anions attaching to the stainless steel surface and yielding an effective negative surface charge. Citric acid pretreatment also suppressed the adhesion of ovalbumin at higher pH of 9.0 and temperature of 80 °C. The adhesion of ovomucoid was also suppressed at both 30 and 80 °C by citric acid pretreatment. These results suggest that the citric acid pretreatment is effective against the adhesion of major egg allergens to stainless steel surfaces.