Effectiveness of Manual and Mechanical Warewashing Methods for Removing Allergen- and Gluten-Containing Foods from Food-Contact Surfaces Used in Retail and Food Service Operations

Effective cleaning is essential for reducing the risk of allergen and gluten cross-contact. This study evaluated the effectiveness of manual and mechanical warewashing treatments for removing allergen- and gluten-containing foods from food-contact surfaces. Stainless steel (SS) polyethylene (PE), and ceramic (CE) coupons were contaminated with gluten-containing (wheat flour; batter), egg-based (egg powder; reconstituted egg powder), sesame-based (sesame flour; tahini), or almond-based (almond flour, almond butter) foods. Maple hardwood (W) coupons were contaminated with only egg- and gluten-containing foods. Wood coupons were then subjected to only the manual wash treatment while SS, PE, and CE coupons were washed using manual and mechanical washing treatments. Coupons were manually washed, rinsed, and then sanitized, in neutral detergent solution, water, and 200 ppm quat sanitizer solution, respectively. Mechanical treatments involved washing coupons in low- and high-temperature warewashing machines. Food residues on coupons after washing treatments were detected with allergen- or gluten-specific qualitative lateral flow devices. Precleaning treatments in combination with warewashing were evaluated for removing tahini soils. Experiments were done in triplicate, and statistical differences between treatments were verified with the JMP® Analysis of Means for Proportion test. Mechanical washing treatments were significantly (p < 0.05) more effective at removing the food soils from the coupons than the manual treatment. Tahini and almond butter were significantly (p < 0.05) more difficult to remove from coupons than the other foods. Multiple wash cycles in the low-temperature warewasher improved tahini removal. Food soil type, washing method, and precleaning methods impacted washing treatment effectiveness. More extensive or specialized washing treatments are needed for some allergenic food soils, particularly food pastes such as tahini and almond butter.