When is a gluten-free meal not really gluten-free?
Cross contamination is when gluten comes into contact with gluten-free food. It most often occurs during food preparation when gluten-free food shares counter top surfaces, utensils, and cookware with gluten containing food. A crumb of wheat bread can contain enough gluten to cause an immune reaction or cause symptoms in someone with celiac disease or gluten sensitivity. Cross contamination is more difficult to detect than hidden gluten. Any safe food can be contaminated with gluten if handled improperly.
Common sources for cross contamination:
Cooking water used for cooking wheat noodles and rice noodles. The wheat noodles will leave enough gluten in the water to coat the rice noodles and contaminate the broth with a significant amount of gluten.
Oil used for deep frying tempura, chicken nuggets, or anything coated in a wheat batter will contain crumbs of gluten. These crumbs can easily cling to french fries cooked in the same oil. Gluten cannot be “killed” by heat.
Crumbs on cutting boards and knives can contaminate gluten free bread and rolls prepared on the same surface.
A stir fry pan used for a dish containing soy sauce or oyster sauce will have enough gluten residue to contaminate the next meal cooked in it. For pans to be safe, they must be first washed thoroughly in hot soapy water.
Toasters used to toast wheat bread cannot be used to toast gluten free bread.
If the oil in a deep fryer has been used to fry gluten containing items (such as chicken nuggets) it cannot safely be used to prepare gluten-free french fries.
A knife used to spread butter/peanut butter/jam on wheat bread then put back into the condiment for a second dip will introduce gluten containing crumbs.
Mixers that are used with wheat flour must be throughly cleaned before using for a gluten-free flour mix.
Airborne wheat flour is very dangerous. It can stay in the air for up to 4-6 hours, then settle on every exposed surface, including clean plates, utensils, counter tops and more.