Like Steak and Eggs

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Postby Copyright_47 » Wed Aug 02, 2017 7:35 am

Like Steak and Eggs – Part 1 (of 2)

This will be talking about Post-Roast Development and Cooling Time considerations depending on the ambient environment you are roasting in.

Like Steak and Eggs, your coffee will continue to roast/cook after discharge. If you were cooking a steak and wanted it to be medium well as you are ready to eat, you would cook it to medium then take it off grill, skillet, or bless your soul, George Foreman. This goes with eggs as well. How many times have you cooked or had one cook eggs for you and by the time you eat it, it is a little tough and really dry. This is because you/they will cook it right to the point where one prepares it to be eaten, only to have it unknowingly continue to cook a little more. This is the same with the bean post-roast once discharged. It will continue to roast in the cooling tray for a few moments. Do not assume it is done once you open the discharge gate. So how long will it continue to roast? Well, there are many factors that can/will play into this. To name the biggest factors:

Ambient temperature.
Examples of what I have worked in: 40+ degrees F in the winter, where the coffee will cool down very quickly ending the roasting process rapidly; and, In the opposite extreme, 115+ degrees F where the roasting process continued as the ambient air (pulled into the cooling tray) is much warmer and will take longer to cool.

Batch size relative to the size of your cooling tray.
As an example, if you have a 24kg(52lbs+) roaster and you are discharging a 40lb roast of a specific coffee with an ambient temperature of 80 degrees F. Then under the same ambient air temp., you are discharging a batch of the same coffee, but a 20lb batch. The 20lb batch will cool a little bit quicker due to less mass needing to be cooled. Now if you are only roasting 10lbs on this roaster, once all has been discharged, stop the cooling trays agitation arm and safely spread the coffee evenly over the surface area of the tray, for this will cool and end the roasting process quicker than having a large mass against the agitation arm while most of the tray is open and exposed. The air will travel through the path of least resistance, being where there is NO coffee to restrict.

Humidity.
Humidity will take an effect on how long it takes to cool down a roast, be it in the cold of winter or sweltering summer. You can have the same coffee, batch size, same ambient temperature, but drastically different relative humidity percentages. This will affect coffee post discharge, continued roasting time as well as total cool down.

Cleanliness.
Keeping all air flow aspects of your roaster clean and free of any debris or build up will decrease the time it takes to cool down and end the roasting process. From cooling tray to flue exit, build up or obstruction will slow the cooling process. The biggest need for keeping all these clean is fire safety. The added bonus is that peak airflow is better for the overall available characteristics of the coffee which the consumer will appreciate.


The time it takes to cool down the coffee once discharged will have an affect that will show in the cup. Without taking the post-crack development and cooling time into account together, undesirable qualities can come through.
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 PrescottCR » Mon Aug 07, 2017 7:15 am

I'm looking forward to this discussion. Hope you don't mind me throwing my observations and questions in:

Perhaps you're going to answer all these questions in the next post but I thought I'd go ahead and ask-

Ambient temp- What have you noticed the difference in temp does and how do you adjust for it? For example, is a ambient temp swing of 20º enough for you do change charge temp or initial flame?

Batch size in cooling tray- I'm guessing that since a cooling tray with a fixed airflow will cool a smaller batch quicker than a larger batch how does that change the coffee?

Humidity- What's the best way to adjust for more humidity? Does the humid air aid or hinder heat transfer?

Cleanliness- I think you've stated the benefits of keeping the roaster clean and in working order. There are a lot of surfaces inside a roaster you can't see but can find with your finger-tips that need attention too.

One thing I would add- Have a plan for what you will do if / when you lose power while roasting. Hot coffee sitting in a drum that isn't turning is a bad thing according to Diedrich. However, a hot empty drum not turning isn't such a risk, so consider that the best thing to do is dump the coffee and lose a batch.

To answer my own questions - I tend to charge @ lower temps and flame in hotter weather (my green bean temps swing almost 20º between winter and summer).

Batch size in cooling tray- Here I don't do anything different from a 5# batch to a 16# batch of roasted coffee. Not so much because I don't care, but because I really don't have any options to change anything. I do have an indoor air conditioner that drops cool air from a hose above the cooling tray for larger roasts during the summer. Don't use it on the smaller roasts. I stole this idea from fellow roasters I spoke with at the 2009 RG retreat.

Humidity- Still figuring this one out. I'm using an IR roaster and humidity comes and goes quickly this time of year so I find myself rolling with it but haven't really compared dry / humid roasts.
PrescottCR
 
Posts: 7
Joined: Mon Jun 13, 2016 4:13 pm
First Name: Richard
Last Name: Gregory
City: Prescott
State: AZ
Zip Code: 86303
Company: Prescott Coffee Roasters
Occupation: Owner/Roaster
Roasting Since (Year): 2006

Postby Copyright_47 » Tue Aug 08, 2017 8:54 am

Hello Gregory,
To keep with the Post- Roast Development and Cooling Time considerations depending on the ambient environment you are roasting in, I will answer some those questioned here not applying to original post that I can do simply in a timely manor. I will get into those in a week.

Ambient temp- What have you noticed the difference in temp does and how do you adjust for it? For example, is a ambient temp swing of 20º enough for you do change charge temp or initial flame?

A swing of 20 degrees is enough for me to adjust my approach to the roast of a coffee for sure. Effects to consider approaching are the fact that the raw beans them selves with swing with that 20 degrees, and also the air that is traveling through the drum will be with said swing of degree.
So for adjusting initial charge and or flame, it truly varies from coffee to coffee. I do not have a single method or two that I use to approach on either side of hot or cold ambient temp. Ex. - A coffee that in the winter likes a very high charge temp with high flame, may like a lower charge with high heat, vis versa or opposite. That all goes to roasting, cupping, roasting, cupping. Being able to have the ability to "play around", making changes that will still keep flavor profile within an acceptable window and seeing what said changes did. But, only make one change at a time, ALWAYS. Then cup.
I also take into great consideration the bean density and batch size. Ex. – On a very cold morning once the drum has tempered I will start off with a coffee with the least amount of density as it will absorb the heat easier than a bean with higher density. This will also fully heat the metal of the drum for higher density coffees. Or maybe you have a profile to a coffee that likes a cooler drum to start. Maybe in the winter, consider starting out with smaller batch sizes and working up to heat the drum for large batches, and in the summer starting with larger working down as the drum really heats up.

Cleanliness- I think you've stated the benefits of keeping the roaster clean and in working order. There are a lot of surfaces inside a roaster you can't see but can find with your finger-tips that need attention too.

I hate to say it, but clean everything. Now as I have told my assistant roasters, vacuum under burner, under cooling tray, chaff collector every day. Use a wire brush for under the cooling tray and in chaff box. Then on top of that, take an extra attention to detail to one portion of an airflow component each weekday, being able to achieve all parts in a work week. Though this does not include the impeller which is done on an as needed basis, and the flue/stacks/chimney which I do every 3 months or sooner depending of volume produced.

One thing I would add- Have a plan for what you will do if / when you lose power while roasting. Hot coffee sitting in a drum that isn't turning is a bad thing according to Diedrich. However, a hot empty drum not turning isn't such a risk, so consider that the best thing to do is dump the coffee and lose a batch.

We have two Diedrichs(Conductions)(5kg&24Kg) as well as a Gothot(Convection)(90Kg). Being inside of tornado alley with severe storms spring into fall, power outage is always on my mind. Now to stress on always being ready, out of all the power outages we have had, about 10% have been during storms. Most happen on the nicest blue sky days. I have flashlights peppered all throughout the warehouse, some even glow in the dark. I make sure everyone knows where they are and what to do in the event.
Our protocol is to always have two able bodies per machine in operation to man a roaster if power and no roaster is to be left alone in the event of a power outage.
As the roaster, yes, discharge the coffee that is in the drum, after the power has been manually shut off on/to the roaster. I say this because with our roasters, we do not have backup generators that will kick on. It takes the turning of the drum to completely discharge all the coffee, which requires one to hold the discharge gate open and one to pull the chain in the back of the roaster to turn the drum(always clockwise with the motor). If the power to the drum is not manually shut off and the power comes back on, the one pulling the chain could be in danger of an accident. Once we get all of the lost batch of coffee out of the roaster, one fans the coffee to cool it down so it does not heat the tray up, possibly warping any metal parts or catching fire to anything and continue to keep the drum turning to prevent any disfiguring that possibly may happen until cool or power is restored. We have had some long chain pulling days, trading off as needed. And as for the Gothot... Pray
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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