Oreo cookie

What Makes Oreo Cookies Black? – the Science of Cocoa Powder

Oreo cookies seem to be omni-present in recipe world. You seem to be able to use them for anything (besides just eating them as such of course). There’s Oreo cookie ice cream, Oreo cookie milk shakes, Oreo cookie pie crust, etc. One of the reasons they’re likely so succesful is their stark dark black colour. A food couldn’t really be much blacker than an Oreo cookie. It’s so black that you wouldn’t even think it was a chocolate cookie! But it is, Oreo cookies get their colour from cocoa powder, there’s not colourant on the ingredient list.

So why is your Oreo cookie* black? Whereas cocoa powders you’d buy in the supermarket are brown (which we compared here)?

Oreo cookie ingredients

As quickly mentioned at the start, Oreo cookies don’t contain any ingredient with a colour except for the cocoa powder. The Dutch cookies (in other countries ingredient lists might be different) contain about 4,6% of skimmed cocoa powder. Besides that they contain flour (main ingredient), sugars, fats (palm oil), leavening agents and some salt, emulsifier and aroma. No colourant.

The flour creates the basic cookie structure, together with the sugar and the fats. The leavening agents make sure the cookie is not a brick, but is crumbly and crunchy instead. The sugar, salt and aroma are there for flavour. And the emulsifier (lecithin) is most likely there because of processing reasons, it makes it easier to mix fats with water. The cocoa powder?: it’s there for colour & flavour (and a little bit of texture as well).

What is cocoa powder?

Cocoa powders are made from cocoa beans. Manufacturers ferment, dry and roast the cocoa beans and then mill them into a paste called cocoa mass. Cocoa mass is a mixture of cocoa butter (a fat) and dry cocoa ingredients (a mixture of a lot of different components). You then transform cocoa mass into cocoa powder by pressing out the majority of the fat. This results in a dry powder which still contains some fat, but a lot less than the initial cocoa bean.

Alkalization changes cocoa powder

Manufacturers can decide to add one additional step to the process before the beans are milled: alkalization. This process was discovered more than a 100 years ago by a Dutch manufacturer, van Houten (which is why you will often find the term ‘Dutch process’ to describe it). He discovered that by adding some alkali (products with a high pH) to the slightly acidic (pH 5-6) cocoa beans would improve their flavour (read more about pH and bases & acids here). The alkalization process makes the beans less bitter, but also changes the colour of the product.

The extent of the impact depends on the concentration of the alkali used. Using a lot of alkali will increase the pH further than using a limited amount which will impact both flavour and colour (as we discuss when comparing cocoa powders).

oreo cookies
The pitch black with pristine white makes an Oreo stand out.

Making it black

Alkalization darkens the colour of cocoa powder. The extent in which the colour is affected depends on a variety of factors such as the origin of the beans and their moisture content. Also, manufacturers can change their process to get the cocoa podwer they want. A higher temperature or higher final pH-value of the alkalization process result in a darker cocoa colour. By optimizing the air flow and steam pressure of the system, the speed of the process can be modified which can again be used to get the desired colour profile.

Generally, the darker the colour, the less astringent the cocoa powder. This will result in less of a chocolate flavour in the cocoa powder. So using the same amount of a pitch black cocoa powder compared to a light brown one will give a less ‘chocolatey’ product.

For Oreos one of those very dark black cocoa powders has to be used. It also explains why Oreo cookies don’t really taste that much like chocolate cookies. The cocoa powder has been alkalized so intensely that most of those characteristic chocolate notes have gone. In exchange it does get some other flavour notes, resulting in the characteristic Oreo!

Innovation in alkalization & sustainability

Alkalization isn’t actually the most sustainable of processes. The alkali that need to be added, such as ammonium carbonate with iron salts, aren’t the best from an environmental and safety perspective. Innovation is on-going within this space to continuously improve the process. The producer of Oreo filed a patent a few years ago stating an improved production method to do so, using more environmentally friendly alkali!

* Oreo isn’t the only black cookie out there! It actually has a twin, the Hydrox cookie, which for some reason never made it as far!


In case you didn’t check the patent on making black cocoa powder yet, here‘s the link again. David Lebovitz also wrote a nice article on the topic.

Moser, A., Alkalizing cocoa and chocolate, June 2015, The manufacturing confectioner, link

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  • I think the oreo wafers are dark brown and its sparked a debate. I understand it is a very dark color but don’t you see really really really dark brown too???

    • Hi Felicity,

      You’re question made me have a thorough look at Oreo cookies again and I guess you could both say they’re black as well as super dark brown. So, if you see them under artificial lighting they look pretty black to me. But in sunlight they do look very very dark brown, especially when I compared them to Hydrox cookies (almost the same as Oreo’s, but different brand), compared to those Oreo’s actually look a little brownish :-).
      The reason behind them being so super dark stays the same though :-)!

  • I recently read with great interest (shock) that Hydrox cookies were the original creme-filled chocolate sandwich cookie and that Oreo’s were the “knock-offs”. As a child of the 60’s, ever loyal to my beloved Oreos, I had believed otherwise. My child’s mind thought that those “icky” Hydrox were cheap imitation ‘rip-offs’of my sacred Oreos bought only by low-class people too cheap to buy the real thing—well I have been enlighten.
    The main reason I am writing is to share an insight to the reason that “Hydrox” may have been so named that goes against the general wisdom I have read in various articles on the Internet.
    I was recently sharing the history of the Hydrox vs. Oreo with a friend from Germany who has suddenly discovered Oreos as they are relatively new in Germany. I was telling him the sorted story of how NABISCO out competed the original Hydrox with their copy. He commented that “Hydrox” was a really ugly name for a cookie and I told him that was my impression as well and the opinion of many others and that it has been speculated that the unappetizing name may have played a roll in the popular cookie’s downfall.
    I have read a lot of explanations of why the cookie was named “Hydrox” in the first place and mostly what is said is that this “Age of science, chemical sounding name” was intended to make people think of something modern, pure and clean like water. This explanation just didn’t ring true to me…
    I read some descriptions of how Hydrox and Oreo’s are made and what makes the chocolate cookie part so dark. Again and again there was a reference to “Dutch cocoa” and a process that uses an Alkaline substance to alter the cocoa. I was explaining this to my German friend who is a physician. Suddenly he said: “Many of the alkaline substances that are/could be used are: Sodium Hydroxide, Potassium Hydroxide, [Whatever] Hydroxide, etc. could that be the reason they are called ‘Hydrox’ “. Suddenly a ‘Eureka’ moment!
    I want here to declare to be the first person [I know of] to put forward the possibility that the name “Hydrox” comes from the alkalized cocoa process used in their creation.
    Please let me know what you think of my hypothesis. Thank you.

    • Hi Chris, That’s a great thought and to me it sounds like it makes a lot of sense. I guess at the time they did indeed think Hydrox sounded fancy, even though we don’t think so anymore, and it could well be true that it originated from a scientist at the company who came up with the name based on the alkalization process. Thank you for sharing!

  • To add one more thought: There could be colouring added, although it is not on the ingredients list. Sometimes companies add burned sugar (very dark black) to a recipe. That could still be very true for Oreo cookies.

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