Effect of Maillard browning reactions of the Kunitz soybean trypsin inhibitor on its interaction with monoclonal antibodies

Carbohydrates react with proteins to form nonenzymatically browned products, including Maillard reaction products. The effects of these transformations on the antigenicity of the Kunitz soybean trypsin inhibitor (KTI) were studied with use of two monoclonal antibodies. Solid mixtures of KTI and carbohydrates were heated in an oven at 120 degrees C, dialyzed, freeze-dried, and analyzed by enzyme-linked immunosorbent assay (ELISA). Glucose, lactose, and maltose decreased the antigenicity of KTI by 60-80%, compared to a control sample heated without carbohydrate. Starch was less effective than the three reducing sugars. This decrease was rapid, occurring within 10 min when glucose was heated with KTI, with retention of 60% of the chemically available lysine. Longer heating times increased browning and reduced the level of available lysine in KTI, without further reducing antigenicity. The results suggest that relatively mild conditions of heating food proteins with carbohydrates can reduce the antigenicity of the protein and possibly modify sites known to elicit allergenic responses