Gluten Fryer Cross-Contamination: Is It Possible?

Gluten cross-contamination is a serious issue for people with celiac disease or gluten sensitivity. It occurs when gluten-free foods come into contact with gluten-containing foods or surfaces. One common source of cross-contamination is the use of shared fryers, where gluten-free foods are cooked in the same oil as gluten-containing foods, leading to the transfer of gluten particles. This practice is often seen in restaurants and food establishments, especially when preparing deep-fried foods. Even after changing the oil, traces of gluten can remain in the crevices of the fryer, posing a risk to gluten-sensitive individuals. As a result, it is recommended that gluten-free foods be prepared separately to avoid any potential health issues for those with gluten-related disorders.

Gluten-free foods cooked in shared fryers with wheat

Celiac disease is a condition that affects 1% of the US population. Those with the disease are often advised to avoid eating gluten-free fried foods that have been cooked in the same fryer as wheat-containing foods. This is due to the risk of gluten exposure through cross-contamination.

Study

A pilot study was conducted to assess the gluten levels of fries that were cooked in shared fryers with wheat-containing foods. The study was carried out by purchasing 20 orders of fries from 10 different restaurants in California and Ohio. The restaurants confirmed that the fries and oil were free of gluten-containing ingredients, and that their fryers were used to cook wheat-containing foods. The fries were then sent to Bia Diagnostics and tested using the R7001 sandwich R5 ELISA and the R7021 competitive R5 ELISA.

Results

The sandwich ELISA found gluten in 9/20 fry orders (7 to >80 ppm), while the competitive ELISA found gluten in 3/20 fry orders (14 to >270 ppm). This means that 25% of the fry orders would not be considered gluten-free.

The study suggests that gluten cross-contact may occur when gluten-free foods are cooked in shared fryers with wheat. As a result, it is recommended that consumers with celiac disease continue to avoid foods that have been cooked in shared fryers.

Other Considerations

It is important to note that the risk of cross-contamination is not limited to fryers. Other sources of potential cross-contact include shared holding trays, scoops, and fryer baskets. Additionally, gluten can be difficult to completely remove from the crevices of a deep fryer, posing a risk to those who are gluten-intolerant or sensitive.

The dangers of cross-contact

Cross-contact with gluten is a serious issue for those with gluten-related health disorders, even when it occurs in microscopic quantities. For those with celiac disease, even the minutest exposure to gluten can cause severe intestinal damage and increase the risk of cardiovascular disease and other serious medical conditions. For those who are gluten-sensitive or gluten-intolerant, eating food contaminated by gluten can cause intestinal distress ranging from discomfort and bowel problems to agonizing pain.

One of the biggest dangers of cross-contact is the universal fryer, where lots of deep-fried food is prepared in the same fryer. This means that gluten-free food could be cooked and sat in oil that is contaminated with flour particles or other gluten-containing foods. Even if the oil in a fryer has just been changed, gluten particles can be difficult to completely remove from the crevices of a deep fryer.

A study by the United States Food and Drug Administration found that gluten cross-contact may occur when gluten-free foods are cooked in shared fryers with wheat. The study tested 20 orders of fries from 10 different restaurants and found that 25% of the fry orders would not be considered gluten-free.

Air fryers can also be a source of cross-contact, as the fan motion that circulates air could blow particles of previously cooked, gluten-containing food onto gluten-free food being cooked.

To avoid the dangers of cross-contact, it is recommended that those with gluten-related health disorders ask about the fryer when ordering gluten-free fried food at a restaurant. Some restaurants have separate dedicated gluten-free fryers, or fryers used only for certain gluten-free foods such as french fries. It may also be a good idea to invest in a dedicated gluten-free fryer for home use if other members of the household consume gluten.

High heat has no effect on gluten

Gluten is a protein molecule, and as such, it cannot be killed. When people say that heat kills gluten, they are mistaken. While heat can damage gluten, it is not hot enough to destroy the gluten molecule completely. Gluten is extremely resilient and tough, and it can't be broken down easily with temperature or time. Even if the structure of the gluten is damaged by heat, it is still gluten.

When exposed to high heat, a process called "denaturing" happens to the enzymes in gluten, which irreversibly changes their shape. However, gluten proteins are very hard to denature. Denaturation occurs when a protein's structure is broken down, causing it to lose its function. Gluten denatures at temperatures over 570° F or 300° C, which is much higher than the temperature of a typical fryer.

Even if a fryer could reach the temperature required to denature gluten, the food would not be exposed to the heat long enough for its internal temperature to reach the denaturing point. For example, bread is usually baked at temperatures between 350 and 475°F (180 and 246°C) and is considered done when the internal temperature reaches 190° F or 90° C, which is well below the denaturing temperature of gluten.

The highest temperatures used in typical food preparation methods such as toasting, baking, frying, deep frying, pressure-cooking, microwaving, and boiling are not sufficient to break down gluten to the point that it's safe to consume for those with celiac disease or gluten intolerance. Even if the oil in a fryer could reach the temperature required to denature gluten, the food would burn before the internal temperature of the food reached the denaturing point.

As such, it is important to avoid cross-contamination with gluten when frying foods. Even a mere speck of gluten protein can trigger an autoimmune response in those suffering from celiac disease. A dedicated gluten-free fryer is the best way to ensure that gluten-free foods are not contaminated.

Cross-contact is rampant between foods with and without gluten

Deep fryers contain oil that isn't switched out after every batch of food is cooked. So, when something like chicken fingers that are heavily breaded in batter are cooked, there's tons of gluten floating around in that oil even after the chicken is removed. So, when you order something like French fries, which are often gluten-free, they can easily become contaminated if they are fried in the same oil. This is a common issue, as many restaurants use the same fryer for all their fried foods.

Even if you have just changed the oil in the fryer and the French fries are the first order you cook, they can still be contaminated. That's because minute particles of gluten are difficult to completely remove from the crevices of a deep fryer.

Air fryers work by circulating hot air around the food being fried. The fan motion that circulates the air could blow particles of previously cooked, gluten-containing food onto gluten-free food being cooked. Don't use the same air fryer for gluten-free and gluten-containing cooking.

A study by the United States Food and Drug Administration found that gluten cross-contact may occur when gluten-free foods are cooked in shared fryers with wheat. The study tested 20 orders of fries from 10 different restaurants and found that 25% of the fry orders would not be considered gluten-free.

Air fryers can blow particles of gluten-containing food onto gluten-free food

Air fryers work by blowing hot air around the food being fried. The fan motion that circulates the air could blow particles of gluten-containing food onto gluten-free food being cooked. This is especially true if the fryer has been used for baking or cooking foods with loose flour, as there is a potential for flour to be circulating in the fryer the next time it is used.

According to a study by the University of California, Los Angeles (UCLA) Digestive Health and Nutrition Clinic, gluten cross-contact may occur when gluten-free foods are cooked in shared fryers with wheat. The study found that 25% of fry orders would not be considered gluten-free.

The Gluten Intolerance Group also highlights the risks of cross-contact with gluten when using air fryers. They advise against using the same air fryer for gluten-free and gluten-containing cooking.

To minimise the risk of cross-contamination when using an air fryer, it is recommended to have a dedicated gluten-free air fryer or a two-drawer air fryer with one drawer labelled as gluten-free. Alternatively, some people suggest cooking gluten-containing meals in the oven and gluten-free food in the air fryer to avoid cross-contact.

If sharing an air fryer, it is crucial to clean it thoroughly before using it for gluten-free food. Most air fryer baskets can be washed in the dishwasher, but those with lots of crevices can be challenging to clean. It is recommended to use an extra tray or silicone liner for added protection when cooking gluten-free food in a shared air fryer.

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