Summary of Roasting

Welcome to my little corner of the blog, friends! As my first contribution to this blog I thought I would keep things simple and just explain a bit about what I do here at New Harvest.

Coffee, as is often taken for granted, is an agricultural product. So before you get that bag of coffee at your favorite shop or market, we get it raw in an even bigger bag, about 132 times bigger. Coffee is the seed of a fruit and in it's raw state, it's not very useful to us. You can't really grind it and it's not very palatable. In fact, green coffee (as it's called) has "only" about 300 aromatic compounds (which would also contribute to flavor) but as it's roasted up to 600 additional compounds may develop via various chemical reactions and the order and time with which they occur. But let's not get too far ahead of ourselves!

Think of green coffee as pure potential. We source some of the best coffees in the world from all over the world and each one of them is different based on a variety of factors from what varietal of coffee it is, how it was produced, where it was produced, at what elevation it was produced, etc, etc... Our goal in the roasting process is to first identify the potential for qualities that we like in each coffee, second, to figure out how to achieve and maximize those qualities and third, to be able to repeat that process consistently each time that we roast a particular coffee.

There are a few different types of roasters but at New Harvest we use what is called a drum roaster. This is probably the most common type of roaster. The way that it works is that coffee is fed into a horizontal drum which sits over a flame and 2 heating elements. There are 2 S-shaped fins inside the drum that keep the coffee inside moving to help promote a more even roast and help prevent scorching. There is also airflow being directed through the drum which in our case would be used to control any quick response we need in temperature. When the coffee has reached our target temperature and time it is discharged into a cooling tray which uses airflow and agitation to bring the coffee to room temperature quickly enough to end the roasting process and prevent scorching.

As the coffee is inside the drum it goes through several stages. The first stage occurs when the chaff, the papery outer shell of coffee, similar to a peanut skin begins to separate. The chaff will collect inside a bin under the drum or else essentially be vaporized in our afterburner. In the next stage the chlorophyll has been burned off from the coffee and it changes from the original drab green color to yellow. At this point a significant amount of moisture has also been lost and the coffee begins to actually roast. Soon enough you'll begin to see some browning as various chemical reactions begin to take place such as the Maillard effect. Eventually the coffee becomes hot enough that the cell structure begins to breakdown and will start to crackle in what we would refer to as First Crack. There is also a Second Crack.

Any changes you make at any point during the roasting process will affect what changes can and will happen later in the roast. A simple way to think about this would be to imagine that a change in the coffee occurs that we will call Red and we make a decision to have a Blue reaction and so our end result is Purple. But say we decide to have a Yellow reaction instead. The our result is Orange. And therein lies the trick to coffee roasting in drastically oversimplified terms. In order to get a coffee to where we like it, we need to create a chain of causes and effects, further complicated by weather patterns, constant moisture loss in stored green coffee, etc, etc... AND it has to be repeatable.

In a way, what we are doing is polishing these coffees. We are attempting to refine something that already innately possesses something great. This was a very simple overview of the process and if you have any questions you can feel free to e-mail me and I will address them on the blog. Even better, you could always stop by the roastery and see it for yourself!