Matt answers your coffee roasting questions: Loring vs Probat

This week Matt Hassell, Global Buyer, QC & Sample Management for Collaborative Coffee Source, and former roaster for George Howell Coffee, has been fielding your roast questions. Here’s a question from @jstnkndy:

@collaborativeCS You mentioned Loring in your last post, can you talk about your experience with Loring vs drum roasters? #ccsqanda

— Justin Kennedy (@jstnkndy) December 12, 2017

Matt's response:

As I briefly mentioned in the last post, I have worked on two different machines. The Loring Kestrel S35 and a 1950’s Probat UG-22. Looking back, it was kind of cool having the chance to learn to roast on two vastly different roasters. There is a difference between a person who is a “Coffee Roaster” in every sense of the title, and someone who just operates a coffee roasting machine. I attribute learning to use a second machine as a defining moment when I considered myself a Coffee Roaster. It forced me to understand why things were happening rather than just knowing how to follow a roast profile.

I first learned to roast on the Loring. Not only a Loring, one of the first ones ever made. It was difficult to find much help to improve my understanding because every resource seemed to be about drum roasters, and there are a few major differences with a Loring.

The Loring basically works like this: heat is pulled off the burner through a cyclone by a fan, then forced into the inlet of the drum. That heat is then forced through the bed of beans, and pulled out by a return fan (that returns the air back into the burner chamber) and the process repeats. Only, the drum is stationary, and the beans are churned by spinning paddles. So, there is no conductive heat, only convective.

Heat transfer rates differ drastically between the two methods. This ended up being the biggest difference between the two. The Loring requires a higher relative burner application to achieve similar levels of development. It took me a long time to figure out what the limits were. My better understanding of them, coupled with Loring’s recent upgrades, has given me a new appreciation for the roaster. I prefer the Loring over drum roasters for espresso roasts, and filter roasts for origins that are your ‘bigger body’ or ‘chocolate, caramel based sweetness’ coffees.

There is a lot of information available in print, both physical and digital, that details how a drum roaster works. They are by far the more commonly used roasters, and in my opinion, are much more intuitive. The one I learned on had some minor airflow and burner modifications, but was mostly as originally designed. Despite being twice as old as me, it was a remarkably consistent and produced a very good roast. The drum, being cast iron, stored a lot of heat. I suppose it depends who you ask, but to me, this was a major positive. I liked being able to back off the burner application heavily, and let the momentum of the stored drum heat carry me through some portions of the roast.

The most useful feature of the machine though, was the airflow damper. This damper, located behind the impeller fan (that pulls the air through the drum) could raise or lower the airflow depending on position, thus changing the ratio of convection:conduction. Proper adjustments can really help minimize some of the variables that we face every day in New England (temperature and humidity variance). These two differences, conductive heat and adjustable airflow, really made me feel like I could hit a small sweet-spot on a coffee. It is for this reason that I preferred the Probat over the Loring for brighter fruit, and higher acidity coffees.

Matt answers your coffee roasting questions: washed vs naturals

This week Matt Hassell, Global Buyer, QC & Sample Management for Collaborative Coffee Source, and former roaster for George Howell Coffee, will answer your roast questions. Here’s a question from @AR0101:

@collaborativeCS what do you need to consider when roasting naturals vs washed coffees? #ccsQandA

— Andres Rodriguez Ruiz (@AR0101) December 10, 2017

Matt's response:

I don’t have nearly the experience roasting naturally processed coffees that I do roasting washed processed. Being in my new position, I find myself with a lot more exposure to naturally processed coffees, so I’ve been re-evaluating my approach and understanding quite a bit. Luckily, I’ve found some fantastic resources to aid in the process.

Roasting a naturally processed coffee requires a longer, slower drying phase and a longer development time. The flavor profile of these coffees is enhanced much more with longer caramelization times. A roast that is too fast, or lighter on the development spectrum may present itself as being harsh and imbalanced. Of course, this is a bit of a generalization as a natural Brazilian coffee would definitely require a different roast profile than an Ethiopian counterpart. They would be unique because of other factors (density, concentration of acids and sugars, terroir, etc.) In general, though, longer times pair with the deeper sweetness and bigger body that is characteristic of natural process coffees. In my experience, I’ve always preferred roasting naturals on a Loring over a drum roaster.

With washed process coffees, you’re able to be much more aggressive with heat application. Shorter roast times with lower-end temperatures have always been my preferred method. This is effective in highlighting the higher acidity found in these coffees. Another point to consider is that washed processed coffees often go through more sorting than naturals. Batches of beans that are more refined in terms of sizing, density, and moisture will be easier to develop homogeneously. You run less of a risk of leaving some of the beans underdeveloped.

Counter to roasting naturals on the Loring, I’ve always preferred roasting washed coffee on a drum roaster. I don’t know why either, because it doesn’t necessarily correlate to coffees that I’ve tasted from other roasters.

Matt will be answering your Twitter roast questions until Dec 12, 2017. Post your questions on Twitter to @collaborativeCS and use the hashtag #ccsQandA.

Matt answers your coffee roasting questions: roast recipes

This week Matt Hassell, Global Buyer, QC & Sample Management for Collaborative Coffee Source, and former roaster for George Howell Coffee, will answer your roast questions. Here's a question from Tom D, @ohthecommotion:

How much of the roasting process is "feel" and how much do you think can be taught? Can I follow a recipe and make a great roast or do I need to just do it for a while? #ccsQandA

— Tom D (@ohthecommotion) December 5, 2017

Matt's response:

This question is so excellent because the answer, for me, has changed dramatically in the last few years.

I think it goes without saying that any task or skill you learn requires a certain level of understanding to not only do it well, but to repeat those results. Lord knows roasting is all about repeating results.

When I first started, people were very nervous to share roasting tips and profiles. There was no Cropster to log, overlay and send roast profiles, or Ikawa sample roaster capable of transferring profiles through text message. There was no ‘Coffee Roaster’s Companion’. Information sharing was scarce. So, I had to rely on being ‘in tune’ with my machine.

The last few years have also brought a lot of scientifically backed research that allows us to understand how to manipulate a multitude of complex chemical reactions and achieve a sweeter, cleaner cup. There are a lot of tools and resources being introduced that help aide in this process. There seems to be a lot more of a science-feel towards roasting than what there used to be.

But, that isn’t to say we’ve progressed to the point where we can just build a recipe for roasting. There are too many variables that are different. Perception of what is “good”, roasting environments (roasting in New England with the weather changes, not fun), and roasting machines themselves (Loring vs. Probat, different location of thermocouple, thickness of thermocouple, etc, etc…) Roasters must be in tune with their machine and have the ‘feel’, that will come with (a lot) of time. But, a good foundation is built on knowledge and understanding.

Matt will be answering your Twitter roast questions until Dec 12, 2017. Post your questions on Twitter to @collaborativeCS and use the hashtag #ccsQandA.