If you're just now joining the conversation, here are links to the first three posts in the series.
So you've read the three prior articles, you've ordered/received your
Sweet Maria's Green Coffee Sample Set, you've dug out an old hot-air popcorn popper you've been meaning to put in the garage sale for the past 10 years, and you're ready to start roasting. (If you don't have a popper then check local thrift stores as they often show up there. I'm sure you can also find them on Amazon.) Excellent - let's do this!
- Setup and turn on popper
- Add 4oz of green beans
- Wait for coffee to roast
- Dump and cool
- Profit!
There... wasn't that easy? OK, fine... I'll go into more detail. However, it really is almost that easy and now you know why I had to write three filler posts before this one.
A green coffee bean is very dense, smaller than when roasted, smell 'grassy', and have approximately a 10-12% water content. The color is typically a dull light green, a slightly bluish green, or grey green. There are some visually observable physical changes that will occur during the roast process. The three most obvious will be a change in color, a change in size, and the sloughing off of the silverskin more commonly referred to as chaff. While these visual indicators are certainly useful and important, there are also audible and aromatic indicators that you will want to become familiar with to aide in determining the roast progress and level. The visual indicators are not 100% reliable by themselves, so it's important to become familar with these other indicators, as well. (In my experience, some of my roasts visually look darker than the other indicators tell me they have achieved.)
As the bean heats up it will first start to lose moisture. The roasted bean will only have about a 2.5% moisture content and will lose up to 20% of its weight. Coffee beans have very strong cellular walls. As the roasting process progresses, physical and chemical reactions will take place which will cause an audible 'crack' as the cellular walls begin to break down and the bean expands and becomes more porous. The completion of "1st Crack" is generally accepted as the minimum roast level and can be referred to as a 'city roast' level. First crack is audibly remotely similar to hearing popcorn pop, though not as loud and not as violent. Leading up to the 1st crack the coffee will expand only a little and the color will tend to turn to more of a yellow and then a mottled yellow brown. Chaff will begin to slough off, but not heavily, though it will be visible on the beans. The smell will progress from grassy, to hay like, to something of a toasted grain.
As heat continues to be applied the bean will reach 2nd crack. The sound at this point can be very faint and is more akin to the sound of rice krispies. This is often difficult to hear over the sound of the roaster. Between City Roast (the end of 1st crack) and 2nd Crack the roast level will progress through City+, Full City (just before 2nd crack), and Full City+ in the middle of 2nd crack. The beans at this point will have expanded (sometimes considerably) and will have taken on progressively darker and more consistent shades of brown. You will be able to smell the carmelization of the sugars in the beans.
If you continue to roast the beans at this point then you will progress through Vienna/Light French, Full French, and charcoal. You will notice the smell will become far more pungent. If these roasts are your thing, then I will continue with my mantra of drink what you enjoy. That said, if you've never tried lighter roasts, I would really urge you to consider giving them a few tries. The first time you try a light roast it could really create cognitive confusion which is why I suggest trying it more than once. It's not exactly an acquired taste, but it can take time to adjust expectations and accept it as appropriate.
Sweet Maria's (of course!) has this excellent
Degree of Roast pictorial with annotations which hopefully sounds a lot like what I just shared and fills in some gaps. Perfect Daily Grind also has
this article that provides a more technical take on what happens during the roast process.
At this point you really are ready to give your first roast a go. As a general rule it really is about 4oz of green coffee that you want to use. If you don't have a scale or that isn't working out for you then add green coffee in small amounts until it just barely stops moving around. That is the max load. As the coffee heats up and loses some weight it will begin moving around again. If the coffee never moves around you're going to get a very uneven roast with some beans burned and others not even roasted, so the movement is essential. If this happens there are a couple common causes. The most common is that you've simply over-loaded the popper and should try fewer beans. If you've started a roast and you're starting to worry about it not moving, use a wooden spoon or similar to manually agitate it some and see if takes off. The other possibility is that your popper isn't putting out enough heat and/or air power. This can especially happen if you have it connected via an extension cord. Try eliminating the extension cord and try again. (Conversely, if you feel like you are roasting entirely too quickly then you can use an extension cord to effectively reduce the power and thus the roast speed.)
As far as the Profit! step... you'll want to store your freshly roasted coffee in a container that has a way for carbon dioxide to escape. If you're using a canister or bag with a one-way valve specifically for this purpose then seal it up and gently squeeze the bag to remove all of the 'air'. If you're using a mason jar then don't seal it completely tight, but do put the lid on it.
You can absoultely brew the coffee immediately after roasting and it should be quite pleasant. However, it won't have had a
chance to degas and to hit its prime which can happen anywhere from a day to 5 days later. The type of roaster used, the actual roasting process (time, temperature profile, cooling, etc.), the roast level, how it's stored, and the bean itself can all impact when the bean will hit its peak flavor.
Is that it? Are we done? The hot air popcorn popper is really easy with only a few common failure scenarios. However, there are tons of ways to roast coffee. I'd like to share some fo these with you and some pitfalls you might run into. I hope you'll explore on your own with different roast levels and I'd also like to provide some insights on what you might expect with each. It's also possible to do some really bad things to perfectly well roasted beans and I'd like to explore that with you just a little bit.
So, nope... there's more.
Let me know if there's something you were hoping I'd cover and I'll add it to the list.
