Patients are commonly challenged with foods containing baked milk, for example muffins, yet little is known about the specific allergen content of muffins used in milk challenges or of the effect that baking has on allergenicity.
Our objective was to compare the levels of major milk allergens in uncooked and baked muffins using monoclonal immunoassays and IgE antibody binding before and after baking.
Uncooked and baked muffins were prepared using recipes from Mount Sinai and Imperial College. Allergen levels were compared by ELISA for Bos d 5 (β-lactoglobulin) and Bos d 11 (β-casein). IgE reactivity was assessed using sera from milk-sensitised donors in direct binding and inhibition ELISA.
Bos d 5 was reduced from 680µg/g in uncooked muffin mix to 0.17µg/g in baked muffins, representing a >99% decrease after baking. Conversely, Bos d 11 levels in baked muffin remained high and only decreased by 30% from a mean of 4249µg/g in uncooked muffin mix to 2961µg/g when baked (~181mg Bos d 11 per muffin). Baked muffins retained ~70% of the IgE binding to uncooked muffin mix. Baked muffin extract inhibited IgE binding to uncooked muffin mix by up to 80%, demonstrating retention of in vitro IgE reactivity.
High levels of Bos d 11 in baked muffins pose a risk for adverse reactions, especially in patients who have high anti-casein IgE antibodies.

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