Gluten Cross Contact in a Shared Fryer: Poster Presented at AOAC International Meeting
View full size poster at HERE.
Abstract: 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.
For more information, including links to a consumer flyer and ppt presentation with audio, see the post “You Don’t Want Fries With That” available at https://www.glutenfreewatchdog.org/news/you-dont-want-fries-with-that/