Cross-Contamination with Gluten by Using Kitchen Utensils: Fact or Fiction?

A risk of cross-contamination exists when preparing a gluten-free (GF) meal in kitchen facilities that usually handle gluten-containing (GC) foods. Cross-contamination with gluten may occur during the preparation or cooking process; however, published data are lacking on gluten cross-contamination from kitchenware. This study was conducted to determine whether cross-contamination occurs through shared domestic kitchenware and, if so, which cleaning method is most reliable for avoiding this cross-contamination. Kitchenware (wooden spoon, colander, ladle, and knife) previously used to cook and/or prepare GC foods was used for the preparation of GF foods (bread and pasta). The gluten concentration of the GF foods was then determined using an established enzyme-linked immunosorbent assay. A PCR assay was also used to detect the presence of wheat ω-gliadin DNA in the food samples. Three cleaning methods were assessed to determine the concentrations of gluten and wheat DNA in GF foods cooked with utensils cleaned directly after the preparation of GC foods. Contrary to our expectations, gluten was not detected in relevant and quantifiable amounts in our samples (<20 mg/kg). The cleaning method used did not influence gluten concentrations: all samples contained <10 mg/kg. Based on PCR analyses, the only sample with lower cycle threshold ( C_T) values (i.e., higher concentration of wheat DNA) was from the contaminated ladle used to serve GF pasta. This outcome led to the hypothesis that shared ladles pose a higher risk for contamination of GF foods than do shared wooden spoons, colanders, or knives. Cross-contamination with gluten in a kitchen environment may occur, but kitchen utensils used for preparing GC pasta and for cutting GC bread should not pose a relevant problem to patients with celiac disease, at least in a domestic environment.