You Don’t Want Fries With That!
For Immediate Release September 24, 2020
Gluten-Free Foods Cooked in Shared Fryers with Wheat: A Pilot Study Assessing Gluten Cross Contact
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Abstract presented at the AOAC Virtual Annual Meeting & Expo, September 2020:
Celiac disease patients are dissuaded from eating fried foods cooked in shared fryers at restaurants based on presumed gluten exposure versus evidence-based research that gluten cross contact occurs. Twenty orders of fries cooked in shared fryers with wheat were purchased from 10 different restaurants. Fries and oil were free of gluten-containing ingredients. Fries were sent to Bia Diagnostics and tested in 1-gram duplicates using the Ridascreen Gliadin R7001 sandwich R5 ELISA and the Ridascreen Gliadin R7021 competitive R5 ELISA (80 extractions total). A microwave control was also run. A 60-ppm gluten mixture of wheat flour and canola oil was tested for gluten before and after heating in a microwave to 190°C using the sandwich and competitive R5 ELISAs. The sandwich R5 ELISA found gluten in 9/20 fry orders ranging from 7 to >84 ppm. The competitive R5 ELISA found gluten in 3/20 fry orders ranging from 14 to > 283 ppm. In the microwave control, the unheated oil and wheat flour mixture tested at a mean level of 64 ppm gluten using the sandwich R5 ELISA and 137 ppm gluten using the competitive R5 ELISA. The oil and wheat flour mixture heated to 190°C tested at a mean level of 55 ppm gluten using the sandwich R5 ELISA and <10 ppm and 16 ppm gluten using the competitive R5 ELISA. Gluten cross contact may occur when gluten-free foods are cooked in shared fryers with wheat. ELISAs may underperform when analyzing for gluten that has been heated.
Tricia Thompson, MS, RD, Trisha B. Lyons, RDN, LD, Amy Keller, MS, RD, LD, Nancee Jaffe, MS, RDN, and Luke Emerson-Mason, MS.