Cross Contamination

Cross Contamination:
When A Gluten-Free Meal Contains Gluten

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 Of 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.
  • 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 four to six hours, then settle on every exposed surface, including clean plates, utensils, counter tops and more.

Preparing Gluten-Free Meals in a Mixed Kitchen

Those who follow a gluten-free lifestyle have two primary concerns: the elimination of prohibited grains and avoiding cross-contamination of gluten-free foods. Very small amounts of gluten (more than 20 ppm) are potentially dangerous to people on a gluten-free diet. Flour dust in the air, shared equipment with dust particles, use of common utensils and baking equipment, and inadequate cleaning are major causes of cross-contamination of gluten-free products.

Ingredients & Equipment

Store gluten-free and gluten-containing ingredients in seperate areas. Clearly label any open containers so that they are not mistaken and contaminated. 

Have separate equipment that is clearly marked and used for either gluten-free or gluten-containing products. This includes measuring tools, mixing bowls, pans, utensils, etc.

Double stock foods that may come into contact with gluten. For example, if a jam is spread on wheat bread and then the knife if put back into the jam jar, that jar of jam is no longer gluten-free. Clearly label the gluten-free version so it is easy to identify. 

Prepare Gluten-Free Meals First

Contamination of gluten-free food is much less likely when all ingredients and equipment are safe and clean. For example prepare a gluten-free breakfast before touching the wheat bread.

Beware of Open Containers

Whenever possible, use squeeze bottles for gluten-free condiments. It is very easy to accidentally contaminate gluten-free foods by introducing tiny wheat crumbs into the jar.

Educate Your Family

Prevent mistakes but also discuss steps to take if a mistake has been made. Help your family understand the cross contamination rules to keep you safe.