Seafood Allergen Transfer in a Shared Breading System

• Seafood proteins accumulate in reused breading mixtures across batches. • Cod proteins are more likely to shed with lower variability than shrimp. • Cod cross-contact in three foods exceeded the FAO/WHO reference dose for fish allergies. • Food surfaces affected the retention of breading particles. • Sieving reduced allergen concentrations but failed to eliminate them at any pore size. Breading systems are widely used in the retail and foodservice industries. However, the risks of allergen cross-contact from reusing breading mixture remain underexplored. The objective of this study was to determine whether seafood allergens, particularly from shrimp and cod, can be transferred to other foods when the breading mixture was reused and to evaluate the effect of sieving on their removal. Up to 20 batches of shrimp (20-30 g/batch) and cod (25-30 g/batch) were prepared separately in a mixing bowl containing 200 g of breading mixture. The same reused mixtures were subsequently used to coat chicken, mushroom, and zucchini to assess allergen transfer. Sieving experiments were conducted using metal sieves of varying pore sizes to evaluate the reduction of allergens in the reused breading mixture. The results showed progressive accumulation of allergens in reused breading mixtures, with cod proteins increasing more rapidly and showing lower variability compared with shrimp proteins. Cod protein cross-contact was confirmed in all subsequently prepared foods, with mushroom retaining the highest concentrations. Sieving reduced allergen levels, with greater reductions at smaller pore sizes; however, cod and shrimp proteins were not eliminated, and substantial losses of usable breading occurred at fine mesh sizes. These findings demonstrate that reuse of breading mixtures can pose an allergen cross-contact risk, particularly for fish, and that while sieving reduces allergen levels, it does not fully eliminate transferred proteins. The use of dedicated breading systems for allergenic foods may help further reduce cross-contact risk.