Steak, coffee, Maillard reaction and pyrolysis

Dany Marquis

Last week, I ate a steak. A banal gesture if it weren't for the fact that the steak in question was worked by my friend Marc Bourg. Marc is originally from Carleton and is an unconditional “Fanboy” of Brûlerie du Quai. You can also drink an espresso if you stop by his store on Beaubien in Montreal.

His website:

Article on Marc:

In fact, by Googling him you will see that he is quite popular and with good reason, his product is amazing! An Angus beef rib aged for 45 days…

But even if Marc does a professional job, you still have to cook the steak... And that's where it gets interesting. Don't cook a steak of this quality who wants, only a seasoned griller can enhance Marc's work without destroying it ;-)

His advice: leave the steak at room temperature, in the air for at least 5 hours before cooking. Preheat the BBQ to 500F°. 3 minutes on one side, 3 minutes on the other side, 3 minutes on the first side on the top rack, remove and leave to rest for 5 minutes. Taste.

And it is by cooking this masterpiece that the link with coffee roasting is made naturally. Because for both the griller and the master roaster, the transformation of the food goes through a common chemical process: The Maillard reaction.

Without knowing it, every day we come into contact with foods undergoing or having undergone the Maillard reaction.

Toasted bread, steak, beer, coffee, same principle, it is the transformation of amino acids, in the presence of sugars and water, at high temperatures and which is responsible for the browning of foods.

So, controlling the Maillard reaction means controlling the taste and appearance of food. When I explain the roasting process to people, I will talk about caramelization of the coffee bean instead of mentioning the Maillard reaction but it is partly this reaction that I am talking about.

The simplest example is really that of a steak which goes from rare to well done in a few minutes upon contact with heat and which will take on a beautiful brownish color. How do you like your steak? The exposure time and temperature will be the parameters to control to satisfy you.

For coffee, we find the same parameters to control for the development of the aromas of the coffee bean. Tank preheating temperature, roasting curve (time vs temperature), endo/exothermal phase control, cooling. It is at this moment, during roasting, that the Maillard reaction operates and we decide on the roasting level of the coffee.

As with all foods, this beneficial reaction can degrade the product if the process is not controlled. Because an overcooked steak, or an overly roasted coffee will lose the essence of its aromas, making the product unpleasant to the taste.

Another aspect that makes the process sensitive is that to speed up the Maillard reaction, the high temperatures to which the food is exposed creates another chemical reaction called pyrolization.

If the caramelization of the bean is the product of the Maillard reaction, the physical transformation of the bean ( 1st crack, 2nd crack, emission of CO2 and CO, loss of density, etc.) is the result of pyrolization. The transformation of the bean during roasting and its degradation once roasting is completed are due to pyrolization. The CO2 emission which carries with it the volatile aromas of coffee are the result of the creation of gas in the coffee bean following its physical decomposition due to exposure to heat. The coffee bean is much denser than a steak, so pyrolysis has a very significant effect on the final product.

So, roasting coffee is the action of exposing the coffee beans to a direct and indirect heat source (convection) in order to develop the aromas (Maillard reaction), color (Strecker reaction closely linked to Maillard) and to physically transform the bean (pyrolise) to make it consumable. Next time you grill a steak, you can impress your friends by describing your complex cooking process. ;-)

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