Skip to content

We did the fast food burgers, now we need to do the fries:

May 26, 2010

As most people now know, McDonalds and Burger King burgers rot almost as fast as an organic burger, as long as a reasonable amount of moisture is present.  The question I have been getting lately is what about the fries?

I ignored the fries in the initial experiment because it has always been my understanding that McDonalds uses a natural preservative that works well with fries, specifically citric acid, for this purpose.  A little research shows that maybe citric acid isn’t the only preservative for these fries.  There is a lot of information regarding how McDonalds fries are made when you search online.

According to we have this:

What is (sic) mcdonald’s french fries made of?

A: McDonald’s French fries are essentially cooked twice. Central suppliers wash, steam-peel, cut, blanch, dry, par-fry and then freeze the potatoes that make the famous golden slivers. During the par-frying, ”a minuscule amount of beef extract is added,” The list of French-fry ingredients that McDonald’s offers at its franchises and on its Web site includes potatoes, partially hydrogenated soybean oil and ”natural flavor.” The list does not mention that the ”natural flavor” comes from beef. To discover that, one would have to contact a McDonald’s customer-satisfaction representative.

So that is how they are made, but what are they made of?  According to here are the french fry ingredients (they are the same in the US):

So, let’s break down the ingredients:

According to wikipedia:(notes in red are my comments)

Potatoes, canola oil, safflower oil.  These things are things we all know about.  I won’t look them up.

This leaves us with:

Hydrogenated Soybean Oil: This one has me a little confused on numerous fronts.  Number one, I can’t find anyone who actually hydrogenates oils to completion.  Almost all oil is partially hydrogenated oil.  I am not sure if wholly saturated oil has any upside.  I don’t think it does.  In any case, I had thought that Canada had made Trans fats illegal, and with a little research I realize just how wrong I was…  Damn the food industry for being so evil!!  Damn the government for being so weak!!  This product is bad, really bad.  You shouldn’t eat trans fats.  I have never heard one person able to defend these things, I cannot imagine how they are still around…

dextrose:  Glucose (Glc), a simple sugar (monosaccharide) is an important carbohydrate in biologyCells use it as a source of energy and a metabolic intermediate. Glucose is one of the main products of photosynthesis and starts cellular respirationStarch and cellulose are polymers derived from the dehydration of glucose. The name “glucose” comes from the Greek word glukus (γλυκύς), meaning “sweet.” The suffix “-ose” denotes a sugar.

Glucose can adopt several different structures, but all of these structures can be divided into two families of mirror-images (stereoisomers). Only one set of these isomers exists in nature, those derived from the “right-handed form” of glucose, denoted D-glucose. D-glucose is often referred to as dextrose, especially in the food industry. The term dextrose is derived from dextrorotatory glucose.[2] Solutions of dextrose rotate polarized light to the right (in Latin: dexter = “right” ). This article deals with D-glucose. The mirror-image of the molecule, L-glucose is discussed separately. (so, dextrose is just sugar, and what french fry would be complete without sugar…).

Disodium pyrophosphate or sodium acid pyrophosphate is a buffering and chelating agent, with many food and industrial uses. It is polyvalent, and acts as a Lewis base, so is effective at binding polyvalent cations.(what does this mean?!?!): Disodium pyrophosphate also is found in frozen hash browns and other potato products, where it is used to keep the color of the potatoes from darkening.[1] Ahhh… that may explain it.  In any case, I have no idea if this stuff is good for you or inert, but this data sheet suggests that eating it isn’t a good idea…

Citric acid is a weak organic acid, and it is a natural preservative and is also used to add an acidic, or sour, taste to foods and soft drinks. In biochemistry, it is important as an intermediate in the citric acid cycle and therefore occurs in themetabolism of virtually all living things. It can also be used as an environmentally benign cleaning agent.

Citric acid exists in greater than trace amounts in a variety of fruits and vegetables, most notably citrus fruitsLemons andlimes have particularly high concentrations of the acid; it can constitute as much as 8% of the dry weight of these fruits (about 47 g/L in the juices[3]).

Polydimethylsiloxane (PDMS) belongs to a group of polymeric organosilicon compounds that are commonly referred to assilicones[1]. PDMS is the most widely used silicon-based organic polymer, and is particularly known for its unusualrheological (or flow) properties. Its applications range from contact lenses and medical devices to elastomers; it is present, also, in shampoos (as dimethicone makes hair shiny and slippery), caulking, lubricating oils, and heat-resistant tiles. As a food additive, it has the E number E900 and is used as an anti-foaming agent and an anti-caking agent.[citation needed] This silicone can be found in many processed foods and fast food items.  This stuff doesn’t sound so bad.  I am used to complex and scary names in ingredients turning out to be harmless food products, and this may be inert.  A cursory search turns up the following… According to this paper, there are some health risks associated with Polydimethlsiloxane.  Apparently it is only approved by the FDA at 10 ppm in foods and it degrades to Formaldehyde at temperatures over 200 degrees Celsius.  I don’t know how hot fry oil is, but I would hope it is less than 200, for our sakes.  Phew, but awfully close.

Hydrogenated Soy Bean Oil with THBQ: We know what Hydrogenated Soy Bean Oil is, but what is this interesting sounding THBQ? tertiary butylhydroquinone??? tert-Butylhydroquinone (TBHQ, tertiary butylhydroquinone) is an aromatic organic compound which is a type of phenol. It is a derivative of hydroquinone, substituted with tertbutyl group. Butyl group? This doesn’t sound good TBHQ is a highly effective preservative for unsaturated vegetable oils and many edible animal fats. It does not cause discoloration even in the presence of iron, and does not change flavor or odor of the material to which it is added. It can be combined with other preservatives such as butylated hydroxyanisole (BHA). As a food additive, its E number is E319, where it is used as a preservative[citation needed]. It is added to a wide range of foods, with the highest limit (1000 mg/kg) permitted for frozen fish and fish products. TBHQ as a food additive is regulated in the United States by 21 C.F.R. § 172.185.[1] Its primary advantage is enhancing storage life.

It is used industrially as a stabilizer to inhibit autopolymerization of organic peroxides. In perfumery, it is used as a fixative to lower the evaporation rate and improve stability. It is also added to varnisheslacquersresins, and oil field additives.  According to Yahoo answers, this stuff is toxic in large doses.  I have found a WHO (World Health Organization) document outlining the Toxicological studies on TBHQ, and in a short perusing, I haven’t found anything that appears that bad.  Mind you, I am kind of scared that they needed to and were allowed to use the name THBQ instead of the whole name…  Seems a little damning to me.


So, I was wrong.  I thought that Citric Acid was the only preservative in the fries.  It isn’t, not by a long ways.  As I have said many times, I don’t think any company as large and efficient as McDonalds would ever put any preservatives in its food that it didn’t actually need.  I know this because, as I have previously pointed out, I need to get down on my hands and knees to beg them for a more than 2 ketchups for 3 large fries.  The actually use the following preservatives and additives:

  • Citric Acid
  • tertiary butylhydroquinone
  • sodium acid pyrophosphate
  • Polydimethylsiloxane

So, I am at a bit of a loss on where to go from here.  I am not sure if I should do more research on the additives or not.  I am not sure if I should create an experiment with fries to see how fast home cooked fries preserved with citric acid rot in relation to these more ‘plasticated’ McDonald’s fries because I don’t know if it would have any meaning.  I guess what I am going to do is ask McDonald’s to explain the additives.  Are they necessary?  Are they safe?  By the way Burger King fries contain the following ingredients: sodium acid pyrophosphate, Disodium Dihydrogen Pyrophosphate, and Xanthan Gum.  Jack in the Box has the exact same ingredients as McDonalds.  You can actually see a great collection of french fry information here.

By the way, never eat fries at any fast food restaurant.  This isn’t because of the preservatives, although that may very well be a good reason, but because they are so high in calories and they don’t fill you up at all.  There is no good thing with french fries or potato chips, so don’t eat them.  Try the side salad or soup instead.  A medium fries has more calories than a cheeseburger and it doesn’t even have a fraction of the protein.   Fries are the emptiest food you can eat and you would by wise to steer clear of them.  Make it a goal of yours to cut them out of your diet, you will be shocked at how big an impact this simple change can have.  It won’t make you fit but it will help.

11 Comments leave one →
  1. June 10, 2010 10:13 pm

    My voice teacher is a bit of a chef (100% Italian guy–he loves to live up to the stereotype!) and he once put a bit of sugar on some french fries he made for us for dinner and told me that it helps them to crisp up, and that many restaurants also use this in addition to salt. So that could explain the glucose. The rest of it is kind of insane. How much preserving (beyond freezing) do potatoes need between being in the ground and being french fries? Scary. At least on a bag of Lays potato chips (empty calories or not–a few with a sandwich every now and again won’t kill anybody), the only ingredients are potatoes, oil, and salt. As it should be with fries.

    • Jamie permalink
      September 17, 2012 1:37 pm

      They are not required to tell you ingredients under 5% unless they are a common allergen.

  2. November 7, 2010 5:29 pm

    Hi Mike,

    Here’s Day 17 of my french fry experiment 🙂

    I linked your post here and your previous burger experiment.

    • November 9, 2011 5:05 pm

      i saw it. nice i am doing the same experiment for my science fair project

      • Ryley permalink
        February 25, 2012 11:10 am

        Me too

      • YouAreNotAFitPerson permalink*
        February 27, 2012 12:32 am

        Would love to see the results… post them here if you get a chance!

  3. November 9, 2011 4:56 pm

    hahahahahahhahha nice

  4. Jamie permalink
    September 17, 2012 1:28 pm

    Just wanted to share some insight with you regarding TBHQ. It is actually extremely bad for you. Its derived from petroleum and is related to butane. 5g can be lethal. Ingesting 1 gram makes your ears ring and causes vomiting. Its known to cause liver dysfunction, cancer, and damage DNA. It is approved as a synthetic antioxidant in the US to preserve food for long times. The FDAs allowed amount is 0.02% within oils and fats based on the WHO putting its allowed daily intake at 0.7mg/kg, which is 1/100th of a lethal amount. America eats close to the ADI. Your body also stores some in fat over time so there’s a little bit of an accumulating effect. Just as a frame of reference 70mg/kg bw is deadlier than cocaine at 95mg/kg bw. Other synthetics used are BHA and BHT which are also butyls. Check your cereal boxes – they’ll usually list it at the end.

    • YouAreNotAFitPerson permalink*
      September 17, 2012 4:44 pm

      Thanks for the heads up. I know when I started to research the fries I was shocked at how much bad stuff was hiding in plain sight. I don’t eat fries any more, although more to do with just how bad a food choice they are in terms of diet than due to additives. Still, I was shocked to see how much crap they add!

  5. Oxiggen permalink
    July 9, 2014 10:13 am

    Ok in our Laboratory we use the PDMS for a manufacturing of flexible optical fibers and optical components. No fast food for me anymore.


  1. Kellogg’s recall « Markvaughan2009's Blog

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: