Let us set the scene; a calm warm and dark room, an innocuous object sitting silently, then all of a sudden, it begins to bubble and bulge; growing and sizing in volume twice, or three times over. The surface of the grown object hardens and an array of peaks and craters form…

… Then the timer dings.


Cookies it seems are like something out of the Cthulhu mythos; a most unbelievable creation.  They were not always delicious and golden, fluffy and chewy. There was a time when cookies, for lack of a better word, sucked.

This horrible time was before what we call the Maillard reaction was discovered. A gent by the name of Maillard in 1912, thought that there was a certain reaction for the way raw ingredients change colour and release carbon dioxide when heated. However, Maillard was not a baker, a patisserie or even a chef; Maillard was a scientist. Originally, he thought that this discovery would be useful for things like diabetes, as this was before insulin was discovered, he didn’t realise how important it was to the production of delicious cookies.

Watch an example here https://www.youtube.com/watch?v=KhLZ2_KTqf4


Maillard might have discovered this trickery, which is why it is now called ‘Maillards reaction’ but it was a guy named Hodge who figured out the chemistry behind it.  (hit me up for a copy of the paper if you are interested :3 )


When you pop the dough in the oven, you are starting a series of reactions. The first is called caramelisation. This is when the sugar breaks down. It transforms from a clear and odourless crystal, to a deliciously fragrant liquid. Overflowing with scents and tastes of butterscotch, caramel and popcorn. The second reaction is the one I previously mentioned, the Maillard reaction. This packs your little cookies with even better tastes. This reaction however uses the protein in the egg, as well as the flour, to stop the cookie from melting out into one huge glob. It is the protein in the egg that halts the cookie from expanding too far out. This is also the reason as to why, sometimes, the difference between gluten free and regular cookies is so apparent. The Maillard reaction helps to create more savoury flavours in the cookie, it also helps to darken!


Engineering cookie perfection…

So I bet you are now sitting there (if indeed you have reached thus far) hypothesising the perfect cookie in your mind; it could be chewy, crunchie, soft or hard, maybe fluffy even? Well, here are a few engineering tips for the next time you try out perfecting your cookie chemistry:

  • The spread – as the dough heats, the butter inside melts. The dough loses its structural integrity and begins to spread out. The diameter is set by how far it expands. An example of this is using melted butter: if you start off with melted butter in the raw dough, instead of chunks of cold butter, the dough is immediately wetter and will spread out faster. So, the temperature of the butter plays a part in the cookie. It alters the air pockets left behind as the water in the butter converts into gas. Melted butter creates smaller holes, equating to a Chewier cookie. Alternatively, if its cold chunks added in the cookie will be fluffier.
  • The rise – so your oven is at about 180 degrees Celsius, or 212 Fahrenheit, the water or liquid in the dough begins to steam. The cookies rise from the vapours pushing through the dough. Eventually the baking soda or baking powder or whatever rising agent you have used starts to breakdown into CO2, WHICH raises the cookies even further. The gases in your cookies don’t just raise it, but they also leave little holes in it to make them light and fluffy :3 You can also switch out the baking soda for baking powder for a fluffier pheffernuies. The baking powder gives the cookie an extra kick of leavening, due to its production of CO2 gas both when its mixed AND when it heats up.
  • Colours and flavours – this is where the real alchemy starts. Just as the cookie is almost done baking, two chemical reactions occur. These two special reactions are what make your cookie delicious and infuse it with its characteristic brown hue. To amp the cookies flavour, you can spike the dough with darker sugars. White granulated sugar doesn’t participate well in the Maillard reaction as it contains more sucrose. Darker sugars, like molasses and honey, are packed with glucose and fructose, which churn out complex tastes and will happily comply with the Maillard reaction.

mad science cookies kelly 001

So a recipe example is needed I think to finish off, I think Tollhouse cookies are a good standard recipe. Here we see the Smitten Kitchen recipe equates to a Chewier and thinner cookie, maximising gluten development and moisture by using melted butter, less flour and less egg white (which also dries cookies out)


Where as here, with the My Baking Addiction recipe, there is a removal of moisture to create a thicker, less chewy cookie. Done by increasing the flour content and using cold butter that spreads less.


So don’t let the apron fool you, bakers are mad scientists.

Sami the science lover,

ask me things! @samiimpossible on twitter