What's Hiding in Our Beloved Fries

Posted by Renee Chan on

What makes fries taste so good? Sure, there are added flavours, but did you know that preservatives are also added to the oil? When oil is used at high temperatures, like in deep frying, it tends to break down via chemical reactions. This produces off-flavours and other compounds that can ruin the taste and the shelf life of food (5). However, one preservative known as tert-butyl-hydroquinone (TBHQ) requires a bit more attention.

What is TBHQ?
TBHQ is a preservative added to vegetable oils used in deep frying. It extends the shelf life of the oil and deep fried products. However, when oil is heated up to high temperatures, TBHQ degrades into different chemicals, one of which is tert-butyl-benzoquinone (TBBQ) (4). Several lab studies have demonstrated that TBBQ can destroy or stop the growth of cells, even human cells (5). 

When food is deep fried, TBBQ can hitch a ride on the food surface then end up in your mouth and your body. Shockingly, TBHQ and TBBQ is way more prevalent than you think, considering that both KFC and McDonalds use TBHQ in their oil and are among the top 4 largest fast food chains in the entire world (1, 2, 3). 

What We’re Consuming
Researchers have simulated real-world conditions to investigate the amount of TBHQ and TBBQ found on fries and in oil. The most interesting result is that the amount of TBBQ decreases when more batches of fries are fried in the same oil. Only a trace of TBBQ was left after 15 - 20 batches of deep frying. 

Secondly, less TBBQ was measured when the deep fryer was used occasionally compared to when the deep fryer was used all the time (5). Which means, if you’re going to eat fast food, try to head to a rural chain that rarely changes their oil. Surprising, isn’t it? Of course, this is still an emerging area of research, despite the fact that many negative consequences associated with TBBQ have been revealed. More evidence and investigation will be needed to evaluate the effects of this chemical on human health.

If you’re interested in learning more about living a more healthy lifestyle, reach out to info@truenosh.com to book a nutritional consult with dietitian Renée Chan. 

Written by: Adam Tong
Edited by: Ev Wong
  1. Chai, C. (2015, January 23). Here are the 19 ingredients that go into McDonald’s French fries. Global News; Global News. https://globalnews.ca/news/1789231/here-are-the-19-ingredients-that-go-into-mcdonalds-french-fries/
  2. kfc ingredients listing. (n.d.). Retrieved January 12, 2021, from https://www.kfc.ca/Content/OnlineOrderingImages/StaticPage/IngredientListingApril2018.pdf
  3. Wikipedia Contributors. (2021, January 9). List of the largest fast food restaurant chains. Wikipedia; Wikimedia Foundation. https://en.wikipedia.org/wiki/List_of_the_largest_fast_food_restaurant_chains
  4. Wikipedia Contributors. (2020, September 3). tert-Butylhydroquinone. Wikipedia; Wikimedia Foundation. https://en.wikipedia.org/wiki/Tert-Butylhydroquinone
Ye, Q., Xia, C., Nie, X., & Meng, X. (2020). Accumulation of 2-tert-Butyl-1,4-Benzoquinone in Frying Oil and Fried Food during Repeated Deep Fat Frying Processes. JAOCS, Journal of the American Oil Chemists’ Society, 97(8), 879–888. https://doi.org/10.1002/aocs.12353‌

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