Learn the science behind:
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).
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!
Moser, A., Alkalizing cocoa and chocolate, June 2015, The manufacturing confectioner, link