Help! I've just been given a HotTop. What do I do?

Fri, 03/05/2013 - 12:07 -- James Oakley

For those who don't know, a Hot Top is a home coffee roaster that operates a bit like a miniature version of the commercial roasters. It roasts in a perforated steel drum that rotates while the air temperature around it ramps up to the right temperature. When the beans are roasted, they are ejected into a cooling tray where ambient air is blown through the beans that are stirred with a paddle. The whole thing takes 20-25 minutes.

So, if you find yourself with one of these machines, how do you start? These instructions are written for the KN-8828, a model that is no longer made, but was the most widely distributed in the UK.

  1. Buy some green beans. Decent ones. Remember GIGO? Garbage-in, garbage-out. I'd suggest something from Has Bean Coffee. The roaster takes 250g per batch, so that's all you need. You may wish to buy several different ones, although there's mileage in buying two bags the same for while you're learning. That way, you can compare the results. I'd suggest something forgiving, too. A Kenyan would be ruined if it went too dark; an Indonesian mustn't be too bright. Something like a Colombia probably has a good range. Don't roast a decaf to start with - they're much harder to get right. Also stay clear of Monsoon Malabar for the same reason.
  2. Press the power button on the Hot Top to turn it on. The Hot Top manual then encourages you to choose how dark to roast, by pressing the "Temp" button repeatedly until you get your choice of 1-7. Don't do that. It's far too course - you have no control. Always choose Temp = 7, then stop the roast when you decide it's time. So press the Temp button 7 times, or until number 7 lights up, then press Start
  3. The machine now starts to warm up. This takes about 5 minutes. When it's ready, it beeps repeatedly at you. Lift the lid, and pour your beans inside. Replace the lid. Now start a stopwatch. You want to record what you've done, as you'll learn from each roast you do.
  4. The beans slowly turn yellow in colour, then pale brown, then golden brown. The smell shifts from drying grass to smell a toast-like smell. About 16-17 minutes later (it varies), you reach a key stage in the roast - "1st crack". How load this is varies from bean to bean, but you're listening for a noise like snapping a pencil. The pops start every few seconds, and at their peak will be 5-10 pops per second. The molecular structure of the bean is changing. The beans darken to a mid brown. And finally the pops die down. You can stop any time from the middle of 1st crack onwards, but for this first roast we're going to keep going.
  5. The next stage is second crack. There can be a gap of 30 seconds to 2 minutes between the end of 1st crack and the start of second, but sometimes there's hardly any gap at all. This is quieter, more like popping corn, or snapping a toothpick rather than a pencil. The little pops are closer together as well. The smell changes, too - less toast, more like burning hay! (Don't believe anyone who tells you they love the smell of coffee roasting - it's the grinding that releases the gorgeous smells!)
  6. When the time comes, dump the beans. Press the "Eject" button on the roaster. A little magnetically controlled tap door opens at the back of the roasting chamber and the beans appear in the cooling tray, and that starts to stir. Five minutes later, the machine will beep a few times before stopping.
  7. If before you're ready to dump, the machine starts to beep, that means it's nearing the end of the time that a "Temp 7" cycle gives you. You're not ready, and the beeping is stopping you from listening to the beans. So press the "Plus" button to get an extra 30 seconds. You can do this up to 5 times before it ignores you and dumps anyway. By this point, you'd be close to combustion, so that's not a limitation!
  8. After the machine finishes, bag the beans into a clean dry bag, prefereably one with a one-way degassing valve on. They will give off quite a lot of carbon dioxide over the next few days, and you want a release for that gas. The added bonus is that the degassing will expel most of the oxygen from the bag, which will preserve your beans. The beans will be at their best 24-72 hours after roasting. (Too soon, they have a funny metallic taste - they need to degas a bit first).
  9. Clean your machine. Pull out the chaff tray and empty in the bin. Wipe the inside of the glass door. Every 2-3 cycles, I remove the 4 screws on the front steel panel (behind the glass door), and remove the drum to hoover out the inside and clear any debris. Don't overtighten those screws when you put them back on.
  10. Eventually, the filters need changing, but the rear filter is every 40 cycles, and the top one is every hundred, so forget that for now.

Never leave an operating roaster unattended. Second crack happens at a bean temperature of about 210 C, so the drum will be even hotter. You get the picture.

You cannot beat fresh-roasted coffee. It only really keeps for a week or two, and being able to roast your own leaves you in control of what coffees you have, and how they are roasted. It's a journey that, once begun, is hard to travel back from. Enjoy!

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Comments

Tom Watts's picture
Submitted by Tom Watts on

Does it work if you roast a little at a time, particularly early on when you're getting used to the process, to avoid too much waste?  Would the method change for smaller quantities?

James Oakley's picture
Submitted by James Oakley on

Truth be told - I've never tried. Looking back at my own roasting log, the smallest batch I've ever put through a HT is 250g. I've done slightly larger batches too (cautiously), and you can get away with it, but that affects the profile slightly.

That probably means that the mass of bean in the drum does affect the temperature gradient. I'd say you could probably try c. 150g - but if you put just 50g in, I wonder if it would heat up too fast, or ...? I don't know. You find get an answer over at toomuchcoffee.com.

Don't worry too much about waste, though. Greens are cheaper than roasted beans. As long as you dump out before the oils show, and after they reach a drinkeable shade of brown and you hear some noise - you'll get some drinkable and tasty beans. It just takes practice to roast each batch to the get the best out of it.

Just do it!

 

James Oakley's picture
Submitted by James Oakley on

... and I've just spotted what I've been using as my own avatar on this site for a few years now. Aahh.. Nice. I roasted that one!

Tom Watts's picture
Submitted by Tom Watts on

I just roasted my second batch. Any tips on chaff removal?

James Oakley's picture
Submitted by James Oakley on

Tom

Firstly, after every roast, empty the chaff tray. It is a steel tray with a black pastic handle, and it pulls out from just under the front of the drum. It runs the whole length of the drum, and catches most of the chaff that falls from the drum during roasting. Just wait until the roaster has cooled, remove the tray, and empty into the bin. You can use a piece of kitchen paper to wipe it cleaner.

That is very important - it's a fire hazard if it's not done after each roast.

Second, either every 3-4 roasts, or more often if you've roasted a particularly chaffy bean. (Dry-processed or natural greens tend to generate more chaff than washed / honey-processed). Remove the observation window of the roaster by undoing the large brass finger-screw on the front. Undo the 4 small steel screws that hold the steel front panel in place, and remove that front panel. You can then remove the drum. This allows you to sweep out / vacuum any chaff that was under the drum. While you have the drum out, you can also use a table knife to dislodge any beans that have got stuck - there are often one or two jammed between the spiral wire and one of the perforations.

To reassemble, you'll see a slot at the back of the roasting chamber. Carefully line the drum up, so that the horizontal bar fits into its slot. Then put the front panel back on, being careful not to over-tighten the screws. Finally, replace the front observation window. Again, you don't want to overtighten the finger screw. You may need to adjust this if the roaster is squeaky next time you use it. The brass screw pulls on the steel front panel. So loosening the screw increases the pressure that the front panel exerts on the drum, whereas tightening it eases that pressure.

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