Sponges for Thought

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Postby Copyright_47 » Wed May 03, 2017 2:08 pm

Sponges for Thought

So along with with our own roasters who are trying to understand the concepts of roasting, I get questions from others and am always willing to throw out any ideas or reasons at any level to help.

Let’s say you have 3 sponges of the same size, thickness, and density. You take all three and soak them in water.

A. Squeeze out as much water as you can. Not completely dry, but no longer wet. Barely considered even damp.

B. Ring out enough to be damp but not completely wet.

C. Soaked, completely wet.

If you were to place all three onto an evenly heated frying pan at a control temp., think about how they would all heat up and how the water would evaporate; at the beginning and throughout until you consider them evenly heated and dry.

The A sponge would bake or burn before it was evenly heated and “dry”.

The C sponge would heat up much quicker, more thoroughly through than the dry (A), but would retain the moisture by the time it is heated bottom to top.

The B sponge would not only heat up quicker than the dry-ish sponge(A), but also more evenly than the wet sponge(C), being able to evaporate the moisture to a level the wet sponge was unable to and the conditions mentioned above.

This is about as simple of an analogy as I can think of for explaining the moisture content of a bean and how it could react or be affected by heat application. Now, size and density play a roll in the approach, as well as the fact that not all beans are created equal. Conduction, convection, hybrid, etc., all have their own benefits and restrictions of what they can do and how they can do it. The trick is to be an operator who thinks a little bit about the moisture content and what it will take to RELEASE that moisture during the roast without baking, scorching, or having a flat cup, and still being able to achieve the profile you are looking for.

Water. Both a friend and an enemy of the bean.

Water can inhibit your roast in many ways, slightly or drastically depending on what the moisture content is and how you approach it. Unless you can just throw away green coffee you think is not perfect, you will have to use what you have, to the benefit of the outcome.

Water is both an insulator and a conductor. Yes, a conductor. In SOLID objects, water actually helps the conduction of heat transfer to some degree. You also need the water content in the bean to help take advantage of the compounds of the bean that increase Maillard reaction. This helps produces the acids that propel the many other chemical reactions in the early stages of the roast. This helps breakdown the proteins for sugar development, through stages of the roast, and also releases the specific acids oh-so-many people enjoy. Taking into account moisture content here, or even just basic realization of too much, too little, or average, helps guide one to the initial starting point: the charge temperature and supply. With this information, you should be able to manipulate the coffee to a final product that will not turn out flat, baked, dirty, or musty in taste. A bean with an “average” moisture content can be approached many ways for so many reasons with the ability to produce greater attributes with less negative characteristics one may have to overcome, more so than a bean with too much moisture content, and even more so than a bean with too little.

How you want to approach that will vary. I have had a high moisture bean that required being charged really high with a lot of supply to push the moisture out and another that required a low charge with low supply that gradually increased allowing for a longer drying phase. I could have swapped approaches for each of these two examples (or made a very slight variation) and achieved a bean with results that would be good, in one way or another, and as a collective chose the one we found had what we were looking for and enjoyed the characteristics. It is the result of trials with forethought that one must choose for the company, business, and customer.

There is NO one method or approach. Though, there should always be thought behind any method to narrow down the approach to eliminate too many developments, wasting coffee, or worse, just settling for a single result.

Now, keep in mind that with a coffee with excess moisture, when it starts to evaporate it will add humidity to the inside of the drum. This will inhibit the roasting as well as flavor and clarity, so be mindful that increasing airflow, even just a little bit, will help in this stage. Increase supply where needed to prevent the loss of ROR. You know, like when you suddenly have a very humid day in late spring or summer, how you would combat difficulties of the extra moisture in the roaster to maintain profile.

If you are wanting to know the moisture content of your coffee and do not have a moisture reader, one thing you can do is contact your importer/supplier of the green coffee. Most importers have this information (as well as other useful information) readily available in their database from samples they take and evaluate upon arrival. All you need to do is ask.

As always, EVERY bean is different, and all can react differently to even the same applications.

Mike - Bean Slave
Copyright_47
 
Posts: 11
Joined: Tue Jul 21, 2015 10:13 am
First Name: Mike
Last Name: Mazulo
City: Topeka
State: KS
Zip Code: 66619
Company: PT's Coffee Roasting Co.
Occupation: Production Manager / Roaster
Roasting Since (Year): 2010

Postby ddelapaz » Thu May 04, 2017 12:34 pm

Mike,

Great analogy with the sponges. Takes an abstract/heady concept in roasting and makes it much more approachable. Some aspects of roasting are more easily understood than explained! I'll have all my production roasters read your post, understand it, and explain it back to me.

Thank you for your contributions to our craft! May your ROR always stay in that sweet spot;-)

Cheers
Derek
ddelapaz
 
Posts: 14
Joined: Wed Jun 15, 2011 8:55 am
First Name: Derek
Last Name: DeLaPaz
City: Minneapolis
State: Minnesota
Zip Code: 55408
Company: Peace Coffee
Occupation: Head Roaster
Roasting Since (Year): 2006
Website: http://www.peacecoffee.com/.
Location: Minneapolis, Minnesota

Postby Copyright_47 » Mon May 08, 2017 11:15 am

Thanks Derek!
I have to come up with simple analogies on several different aspects/topics. I will fine tune those and put them out here for anyone. If it can help just one person it is worth it to me to put it out there.

May your ROR always stay in that sweet spot as well!
Copyright_47
 
Posts: 11
Joined: Tue Jul 21, 2015 10:13 am
First Name: Mike
Last Name: Mazulo
City: Topeka
State: KS
Zip Code: 66619
Company: PT's Coffee Roasting Co.
Occupation: Production Manager / Roaster
Roasting Since (Year): 2010


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