I seriously have had a CHEF explain that ‘while they don’t have a separate fryer for the gluten free chips and calamari, their oil is set at a hot enough temperature to ‘burn it off’!!!
I have also heard of restaurant staff talking about gluten getting ‘killed’ by the hot temp of the oil!!
This level of ignorance by some professionals in the food industry is obviously very concerning.
So lets establish the facts.
Gluten is a protein molecule. It cannot be ‘killed’.
Gluten can however be denatured (have its structure broken down) through extremely hot temperatures. It is thought that it requires a temperature of over 260°C for this to occur (1). Most commercial fryers are set at between 130°C and 200°C. If in fact one was set at 260°C, the food being cooked would simply burn…basically turn to charcoal!
Additionally IF gluten was destroyed in this way then the food containing gluten would also lose its glutinous structure and consistency…ie. the batter or bread crumbs would not hold together…(2)
So if your fish and chips or calamari come out with a nice golden intact crispy coating, then gluten is still very very present.
Remember, it only takes one crumb!
One crumb (50mg of gluten) is all that is required to trigger the reaction of the immune system in a coeliac to attack the lining of the intestine (3). Lets get even more specific…the gluten protein molecule is actually made up of smaller sequences of amino acids. It is one particular sequence, the gliadin component, that is known to be the trigger for the coeliac auto immune reaction, causing the gliadin-specific antibodies to go on the attack. Just ONE molecular sequence can trigger this reaction. Just one crumb.
So, regardless of the temperature of the oil, regardless of how long it is cooked for, and even if the gluten was mostly broken down (& the food was subsequently burnt and falling apart!), there would STILL potentially be enough of the gluten protein’s sequential molecular structure remaining intact within the oil/food item to trigger an auto-immune response in a coeliac.
Mind you…the coeliac at this point wouldn’t eat it as IT WOULD BE MOSTLY CHARCOAL!!
(1) Does Heat Destroy Gluten? (2017) www.coeliacsanctuary.co.uk
(2) Elmehdi (2013) Probing Thermal Transitions & Structural Properties of Gluten Proteins Using Ultrasound, www.ncbi.nlm.nih.gov
(3) Coeliac Australia (2018) www.coeliac.org.au
I would LOVE to hear your STORIES, good or bad, in the COMMENTS below, about the use of shared fryers for gluten free food in the food industry
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I’m so glad I came across your blog! I was out at a restaurant last night with my husband and they had the jerk chicken as gluten free but they didn’t have a dedicated gluten free fryer. I told them I’m celiac so I was not convinced and our server got a fellow server who said that they are celiac as well and that the fryer when it gets to 400 degrees kills the protein in gluten and that I would be fine as she herself has eaten the jerk chicken and had no reaction as a celiac. I was very confused and so I started to research her comment today and low and behold that was not a true statement. My concern is that their menu is calling out dishes as gluten free and educating their staff with the wrong information. Thank you for posting!
Hi Meaghan, oh I am so glad this article was able to provide clarity and help you to continue to avoid that risk. It is very concerning that basic coeliac safe food handling & prep is not a mandatory part of any food handling training. It is something that Coeliac Australia is working hard to fix so that scientific understanding in restaurants & cafes keeps us safe!
I really don’t understand. When I cook a roast the oven temperature may be 200 centigrade. However, if I measure the temperature of the meat with a meat thermometer it is less than 70 degrees when fully cooked well done. Gluten is a protein that denatures. That is to say ceases to be gluten at around 75 degrees. As baking a loaf of bread does not see the temperature rise above a this I totally understand why coeliacs cannot eat it. However a single bread crumb in deep frying oil heats up to over 125 degrees because it is so small the heat would completely penetrate and theoretically destroy the pluten protein molecules.
My sister is a coeliac and as we all know experimenting with food is a dreadful idea. Soo she always checks before eating fried food. However, my son got a job at a Pizza place where they cook gluten and non gluten pizza in the same oven. She has never had a problem with one of these pizzas. Although now we avoid this restaurant completely.
My question is has anyone done any scientific analysis of say a breadcrumb that has been left in boiling pill for 5 minutes to see if any gluten remains. If they have can you point me to a link?
Hi Tony, Thanks so much for your comments. (And so sorry for not replying sooner…my blog has been somewhat neglected for the last couple of years due to the busyness of my hamper business…but am happy to be able to get back into it now)
In the article the research indicated it takes temps of over 260 celcius to denature gluten, so this would not occur in either the oven or hot oil. The concept of it taking only one crumb of bread to trigger the auto-immune reaction of a coeliac is the current medical understanding in Australia, as stated by Coeliac Australia (based on varied scientific research they would have references for).
Regarding your sister’s experience with the pizza oven, coeliacs can have quite varied levels of tolerance to cross contamination, and this can also change over time within the one individual. There are many situations where I did not react not long after diagnosis, but now I react strongly. It is therefore just safer for all coeliacs to make every effort to avoid cross contamination hazards, and hot fryers is definitely one of those.
I have a question about cast iron. If a pan was used with normal bread does baking it in the oven at 500 degrees For an hour denature the proteins to maKe it safe again. It appears that is the case from my reading.
Hi Henry, Good question. I would definitely imagine it would. However, pans only need to be washed in detergent and hot water to remove gluten residue and make them coeliac safe.
Hello,
I Have recently purchased a 100% millet sourdough loaf that had denatured gluten as part of the ingredients list. Would that bread still be gluten free? I have a sensitivity to gluten, so I prefer to avoid it all together.
Thank you tons,
Cheers,
Rita
Hi Rita, Thanks for posing a great question. Alot of sourdough is proported to be fine for the gluten intolerant as it does naturally contain less gluten. However they are definitely not OK for coeliacs. I have a link below to a study which tested the claims of some breads that have denatured gluten, showing there is still sufficient gluten molecules to trigger an auto-immune response in coeliacs. They also recommend that they are avoided by those who are gluten sensitive. It is hard to know the nature of the particular bread you are referring to, without seeing the nutrition panel, or having it tested, but I would assume the recommendation would be to avoid it.
https://www.glutenfreewatchdog.org/news/sourdough-wheat-bread-is-not-safe-for-folks-with-celiac-disease/