Do Convection Ovens, Toasters, Microwaves, and Air-Fryers Pose a Gluten Cross-Contact Risk?

Are you curious if common kitchen appliances, like a convection oven or toaster, pose a threat of gluten cross-contact or contamination? In this article, I’ll explore the risk, supported by data, to help you make an educated decision about what appliances you can safely use when following a gluten-free diet. This post contains affiliate links. Please see my disclosures.

Researchers of a published study in Frontiers in Nutrition found that many individuals following a gluten-free diet regularly consume a significant amount of gluten, enough to trigger “severe symptomatic responses” and “histologic damage” in people with celiac disease.

You might wonder where this inadvertent gluten exposure comes from and whether or not common kitchen appliances contribute enough gluten to cause symptoms and damage in people with celiac disease or non-celiac gluten sensitivity.

In this article, I’ll discuss whether or not someone can be exposed to gluten, a protein found in wheat, rye, barley, and sometimes oats, simply by cooking their food in a shared kitchen appliance.

Conventional and Convection Ovens

Conventional or standard ovens don’t pose a gluten cross-contact risk in most cases and can safely be used by the gluten-free community with little worry about the potential of gluten cross-contact.

However, when simultaneously cooking two dishes – one that contains gluten and the other gluten-free – put the gluten-free dish on the top shelf to prevent any non-GF foods from dripping into the gluten-free dish. You can also cover the gluten-free dish to protect it from accidental exposure in a shared oven.

Further, never cook food, like a pizza, directly on the oven grates in a shared oven. Instead, place a baking sheet, foil, or parchment paper below your pizza to minimize the potential for gluten cross-contact.

When cooking with the convection setting on your oven, you may want to take added precautions.

Convection ovens use a fan to circulate the warm air around the food. This helps to cook foods evenly and crisp foods quickly. While you wouldn’t use the convection setting to bake a moist, leavened cake, you might use it to roast potatoes so that the sugars in the potatoes caramelize faster and become crispy and brown more quickly.

Given that the convection setting will circulate air inside an oven and, therefore, can circulate gluten dust particles, it poses a slight gluten cross-contact risk in some cases.

There are a few things you can do to protect yourself when using a convection oven:

• Don’t cook gluten-containing and gluten-free dishes in the same oven, especially when using the convection setting. The gluten from one dish can and likely will circulate and land on the gluten-free dish.
• Clean the oven before using it for cooking gluten-free food. If this isn’t possible, cover the gluten-free dish to protect it from potential gluten dust particles.
• If you have a double oven in your kitchen, designate one for gluten-free foods only.
• Don’t cook foods directly on top of the oven rack, especially if using a shared oven. Use a baking sheet or foil.
• Assess the actual risk. Even if the oven is shared, the risk of a significant amount of gluten dust spreading is minimal. Worrying about the type of oven used to cook your food at your friend’s house can lead to food fear and hypervigilance, so use your best judgment when deciding on what food is and isn’t safe for you.

Toaster Ovens

While most people with celiac disease or severe gluten intolerance use a separate toaster to toast gluten-free bread, and while I highly recommend having a dedicated toaster oven, it’s important to understand that the science doesn’t fully support this recommendation.

In fact, researchers set out to determine if gluten-free bread toasted in a shared toaster would contain detectable levels of gluten above 20 parts per million (ppm), which is the amount of gluten a product can contain to be “legally” labeled “gluten free” per the FDA’s gluten-free labeling guidelines.

After toasting a slice of gluten-free bread in a shared toaster, one with a visible accumulation of crumbs, researchers surprisingly didn’t find gluten transfer above 20 ppm. This highlights the fact that some kitchen appliances pose less risk of cross-contact with gluten than is commonly believed within the gluten-free community.

Truth be told, this is a limited study in one controlled scenario. In a busy kitchen environment, say a popular brunch restaurant, would these results be replicable? The answer to this question is unknown, and it’s why many gluten-free experts recommend avoiding shared toasters or using a protective toaster bag.

Microwave Ovens

Microwave ovens can safely be shared among those that eat gluten and those that follow a gluten-free diet.

Because food can splatter and pop in the microwave, it’s best to heat gluten-free food separately. And it goes without saying that if food spills or splatters inside the microwave, the person making the mess should clean the microwave immediately.

Air Fryers

Air fryers are a popular way to cook and reheat food these days, but they can pose a serious risk of gluten cross-contact for people with celiac disease or gluten intolerance.

Air-fryers work by circulating warm convection air around the food. This helps make food crispy and brown on the outside and soft and juicy on the inside.

While thoroughly cleaning an air fryer between uses will eliminate some of the risks of using a shared fryer, it’s not a foolproof method. Until further research is available proving a shared air-fryer is safe, gluten-free people should avoid using a shared air-fryer and instead invest in a dedicated gluten-free air-fryer of their own.

Pizza Ovens

Pizza is one of the riskiest foods a person on a gluten-free diet can eat, especially when it’s prepared in a restaurant, which is riddled with airborne flour, shared ingredients, and shared pizza ovens.

At home, there are a variety of methods to cook pizza, whether it be in your conventional or convection oven (see above) or a portable gas-powered oven like ooni.

There is no evidence that discusses the potential risk of gluten cross-contact in household pizza ovens. Therefore each person will need to assess their unique situation to decide how to proceed.

While most household pizza ovens don’t circulate air like a convection oven (although some do), it’s important to minimize your gluten exposure by cooking your pizza on a clean surface along with placing a piece of parchment paper below your pizza. Also, be sure to use a clean pizza peel and stone.

Also, despite what you may have heard, heat does not kill gluten. Even though pizza ovens become extremely hot, their heat will not eliminate the risk of gluten exposure.

Grills

Grills can pose a significant risk of gluten cross-contamination, not from the circulation of air, but due to contaminated surfaces. Gluten particles can accumulate on the grill grates and thereby contaminate other foods.

If using a shared grill, consider the following:

• Designate half of your grill for gluten-free food; be sure everyone who uses your grill complies with this separation and uses separate utensils for handling food from each side.
• Either invest in a set of grates used for gluten-free grilling only or, for a simpler option, use a grill mat or foil to line the grill before using it for cooking gluten-free food.

Bottom Line

Using shared kitchen appliances can cause a risk of gluten cross-contact in some cases, such as in convection ovens and air fryers. However, many shared appliances have limited risk and should be assessed on a case-by-case basis.

As always, it’s important to balance the risks associated with each scenario along with the joys of life. Finding ways to enjoy food safely without feeling fearful or judged will remain a constant challenge for the gluten-free community.

Additional Reading

• Setting Up a Gluten-Free Kitchen
• Does a Crock-Pot Absorb Gluten?
• The Emotional Burden of the Gluten-Free Diet
• Are Lentils Gluten Free?
• What is Gluten Cross Contamination?
• Understanding Gluten Cross Reactivity and Gluten Cross-Reactive Foods
• What Gluten-Free Labeling Laws and Certifications Really Mean