This is not a question about the merits of BHA or BHT (butylated hydroxyanisole or butylated hydroxytoluene). It is a question about how BHA/BHT work when "added to packaging material".

The BHA is often added directly to food, where it has an antioxidant effect keeping fats from turning rancid during storage. But often, especially on whole grain breakfast cereals, BHA is listed as "added to packaging material".

What mechanism allows the BHA/BHT in the packaging to protect the food? Does it adsorb free radicals for example? Or "added to packaging material" just a marketing trick, because the BHA/BHT actually must migrate to the food to work?

[Ref 1] Encyclopedia of Food and Color Additives, edited by George A. Burdock

  • So, yes. It protects the food by "migrating" into it. – Dr. belisarius Sep 30 '14 at 22:50
  • @djmadscribbler Chemistry is far away from my "area of expertise". I've found a scientific paper that seems to answer the question but I'm not able to extrapolate some important missing info. For example: What was the BHT concentration found in the food after the test?. Are the "freeze-dried model food" used for testing a valid equivalent to cereals? Without understanding those pieces you can't figure out the potential consequences/dangers involved. And answering "yes, the BHT is transferred to the cereal" looks like a very poor answer to me :) – Dr. belisarius Oct 1 '14 at 21:58
  • @belisarius it looks like you've found the answer and a solid reference. Move it the answer section and earn points. – Bryce Oct 2 '14 at 16:23
  • @seasonedaddict Please don't start off-topic discussions in comments, and please be polite to other users on this site. – Cascabel Oct 3 '14 at 21:33

BHA, BHT and/or TBHQ aren't added to the packaging to keep the cereal from spoiling. It's actually added to keep the box from spoiling.

As you stated, BHA and BHT slows down the oxidization of fats and oils. It keeps them from going rancid. And while some of this preservative will migrate into the cereal, many cereals don't actually have any fats or oils. The grains that go into cereal, be it corn, wheat, or oats, contain a small amount of fat and protein in the germ, or the tiny little center of the kernel. During production, though, the grain is degerminated, precisely because the fats in the germ spoil so quickly. Whole grain cereal, though, still has its germ. This is great nutritionally, since most of the vitamins and protein are in the germ, but then, so is the fat. And fat goes bad. So some of the BHA and BHT in the plastic bag is meant to migrate into the food. This is a bit of a semantic dodge for marketing purposes- it's not in the food, but it will be soon.

A lot of non- whole grain cereal is completely fat free though, but will still be packed in a box with BHA, BHT, and/or TBHQ. So where is the fat coming from?

During the 90s, most companies transitioned from brand new white cardboard to recycled brown cardboard. And just as importantly, they transitioned from petroleum based inks to soy based ink. Now, soy based ink is great for the environment because it biodegrades in the trash, but therein lies the problem. The soybean oil in the ink biodegrades. It goes rancid. The colorful graphics printed on the box will eventually taste and smell a bit off. Not only that, but the recycled paper is going to already contain some rancid ink from the newspaper and boxes that it was made of.

Now, the plastic bags that cereal are packed in are very, very, close to being air- and liquid- tight, but they are not perfect. In the course of sitting on the shelf, they will absorb odors and tastes from the outside world. This includes the smells and tastes of rancid box ink. In order to guard against this, manufacturers add preservatives like BHA/BHT to the box ink. Because the food is also absorbing some of those preservatives in the box, legally, box preservatives are also listed as a food ingredient.

Our societal push to recycle paper and save trees has some odd implications for food packaging.

Ink now has to have preservatives if it is going to be close to food. The plastic bags inside the box also have to be thicker because the boxes that our food are stored in already contains some rotten ink. And finally, we now eat more preservatives in our cereal, because the cereal absorbs some of the box.

  • but is the ink still biodegradable if it has preservatives added to prevent its degradation? – rumtscho Oct 3 '14 at 10:06
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    The ink still breaks down- the preservatives will slow down the process a lot, but it won't stop it completely. Antioxidants, be it vitamin C or BHA/BHT work because they absorb oxygen faster than the material they placed in- but eventually all of the antioxidants will be consumed, and natural decomposition will continue. – Tenway Norsing Oct 3 '14 at 10:33
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    This is, incidentally, why BHA/BHT and vitamin A are dangerous in very high concentrations- because they are both fat soluble, they are not excreted from the body very quickly, and the antioxidant action blocks some of the body's natural chemical rxn's. This is why eskimos don't eat much whale and seal liver- too much vitamin A. Conversely, you shouldn't eat too much cardboard box and plastic bag- too much BHA/BHT. – Tenway Norsing Oct 3 '14 at 10:45
  • I should try to remember that next time I'm so hungry I take a bite out of a pizza slice and realize I also got the cardboard holder :P But seriously, very interesting information. – rumtscho Oct 3 '14 at 11:01
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    The BHT is added to the bag, and may also be added to the backside of the cardboard in the form of a thin plastic film. I tried to find some publicly available sources, and this is the best I found- pkt.jinakarn.com/apfa.pdf and google.com/patents/US4880696 – Tenway Norsing Oct 3 '14 at 21:09

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