Roaster Upgrade

Recently we purchased our new roaster (which you can read about on the site here) https://silverskincoffee.ie/2019/04/10/new-equipment/

In a bold move, we decided that our existing 15kg roaster would be upgraded to match the roasting style of the new machine.

This meant taking out the existing drum (thermodynamic) and replacing it with a new one (Vortex).

Here is a note on both technologies.

 

Thermodynamic Drum: The most advanced drum available in today’s industry. Built from two layers of mild steel with a middle layer of pure copper, it has extremely high thermal absorption and heat conduction characteristics. In contrast to standard drums in which roasting is performed by direct, limited contact between the beans and the drum. The Thermodynamic Drum exhibits a unique scheme of sophisticated heat conduction applied to a wider contact surface between beans and drum. Heat is transferred via the copper layer creating a 1.4 mm gap between the heat and the beans, removing any risk of burn marks. This drum excels in producing an evenly roasted batch of superb beans, allowing a higher range of temperature operation, and writes its own new language in thermal dialog – just imagine, reflected heat conduction.

 

Vortex Drum: Drum air-inlet screens configured at vortex geometry to allows very efficient high velocity air. This drum is 4 mm thick, made of two separate layers of perforated mild steel.
The perforated drum utilizes infrared radiation for roasting. The radiation is produced by the flame which is positioned horizontally, parallel and underneath the drum inside the ceramic combustion chamber. This drum is indifferent to the type of rare plate as air flows through the drum walls and around. This drum also requires low airflow to prevent excessive conveying heat by the air.
The perforated drum produces a stronger taste and a higher rate of caramelization in sugars. This much desired outcome occurs without running the risk of producing roasts with burnt marks on the surface of the beans as may happen while caramelizing with solid drums. Using this drum may prove favorable for filter coffee roasters or those who seek to obtain intense tastes for their espresso roasts.

No easy feat especially when the bearing housing at the front of the roaster refused to let go! Eventually we separated the old drum and installed the new one (which is considerably bigger) this meant adjusting the combustion chamber slightly or simply put saw away some of the protective housing *scary stuff.

One of the main reason for the adjustment to the housing was for the new burner to be placed inside. The old burner was a Pre-mix single nozzle**

 

Pre-mix single nozzle burners are first level new-generation gas burners. Not only that, they can operate as multi-fuel burners. Such burners are equipped with a centrifugal blower able to calibrate air quantity. They also come equipped with a calibration valve that controls gas quantity. Controlling gas quantity ensures air and fuel mix in accurate amounts resulting in complete combustion that derives maximal caloric value.

Just like with anything else, there are many manufacturers of these burners. Design and quality naturally vary. In a good quality burner, a projecting/radiation nozzle or a heat-radiating metal screen will be installed to supplement the mixing chamber. Such efficient setup secures oxidation at the tip of the flame. This gets rid of toxins such as NOx and SOx generated by improper gas combustion. In its more basic form, this burner cannot be modulated using a single control knob. Modulation requires optimizing air quantity manually with almost every single change in desired gas quantity.

 

This was upgraded to a Fully modulated burner  with greater control for sure ** see a note from the manufacturer about it’s high cost and over exuberance……if you’re gonna do it you’re gonna do it though right 🙂

 Fully modulated burners

Just like in the single/mono stage, in pre-mix single nozzle, multi-stage, or fully modulated burners caloric value can be changed and adjusted during roasting. With this type of technology, where the burner is located in a closed combustion chamber with optimal heat distribution, there is no need for full-resolution control. Two or three stages will provide perfect control for all commercial roasting purposes. Some roasting masters will nevertheless consider this insufficient. That is also fine: the technology is already here to match. As long as you promise to use it and are willing to pay for it, it can certainly integrate into your made-to-measure roaster. However, sometimes, high functionality can also be a source of confusion. Some clients are better off without a wide control range. Trust me, I have been supporting clients online for way more than twenty years since the early days of the Internet.

Having said that, 100% control is vital when the flame hits the drum directly. In this case, it is absolutely necessary to be able to go down to very low caloric values. On the opposite end, when the drum compartment is open and un-insulated, one has to take into account the cold surrounding air that interferes with the roasting process.

 

So simple really we have upgraded our existing roaster to ensure all roasts, all styles match up no matter which machine we use. Its been a huge learning curve already but one we are thoroughly enjoying.

if you’re following our intstagram you’ll see the hours spent uninstalling and reinstalling the kit.

 

Hopefully its worth the effort for our customers.

 

Brian

New Equipment

Anybody who knows me knows I like coffee kit, gadgets & equipment. The roastery is literally jam-packed full of such kit (the packing line being the coup de grâce)
Well if you’ve been following our Instagram you’ll know that I am back scratching that itch.

This month we took delivery of a new dispenser for packing retail as well as a new sealer. We also have this beauty en route a 30kg monster that is loaded with extra special features (my favourite being the chaff pelletiser, burning chaff in a stove just seems epic to me).

An auto loader for filling the charging hopper along with some very special tech going into the drum will ensure we can roast high quality produce into the future. I look forward top updating you soon.

Brian

Here is some technical data/ research on drums for reference.

Coffee-Tech engineering is proud to present the latest developments in our Drum Thermal Behavior Research Project on roasting drums.
For several years we have conducted an extensive R&D project in which we have been investigating the impact of material, shape, volume and motion on the performance of the roasting drums we feature in our various machines.
The outcome of that project is three distinctive types of drums offered for the Ghibli line, aimed to realise three different goals with a distinctive edge for each purpose.
Coffee-Tech Engineering’s Standard Drum
Our standard drum is built using solid mild steel, 3 mm thick. This drum is used in our Ghibli R-15 roaster, with 5 mm thick steel for larger models up to our 90Kg batch machine.
The drum was designed on 3D animation software and welded with crossing agitation blades for perfecting key features such as smooth motion, heat conduction, chaff evacuation and rapid beans evacuation for the cooling.
Both material and configuration were thoroughly studied for obtaining high conduction roasting, allowing a wide aromatic spectrum and high levels of sugar to develop during roasting. This drum is expected to produce superb roasts in most roasting styles, including blends roasted for espresso.
There are two variants of back plates for this type drum:
Perimeter Air Passage Holes Back Plate:
This plate causes air to work at the contact points of the drum surface and the beans. The result is milder and finer heat conduction and enhanced heat distribution.
Centered Air Passage Holes Back Plate:
This plate restricts the amount of air flow, increases its velocity and enhances convection inside the drum. This will perform well in machines equipped with the drum blower speed controller.
Coffee-Tech Engineering’s Infrared Drum
This drum is 4 mm thick, made of two separate layers of perforated mild steel.
The perforated drum utilizes infrared radiation for roasting. The radiation is produced by the flame which is positioned horizontally, parallel and underneath the drum inside the ceramic combustion chamber. This drum is indifferent to the type of rare plate as air flows through the drum walls and around. This drum also requires low airflow to prevent excessive conveying heat by the air. .
The perforated drum produces a stronger taste and a higher rate of caramelization in sugars. This much desired outcome occurs without running the risk of producing roasts with burnt marks on the surface of the beans as may happen while caramelizing with solid drums. Using this drum may prove favorable for filter coffee roasters or those who seek to obtain intense tastes for their espresso roasts.
Coffee-Tech Engineering’s Thermodynamic Drum
This drum is 5 mm thick in total, made by 2 different layers of mild steel and a third layer of 99.9% copper located in between both layers.
This drum has the best thermal absorption and conduction characters; the copper layer evenly distributes the heat all around and conveys it to the perforated, rough surface “in drum beans contact layer”. This structure allows better conduction and better beans agitation (anti sliding). The 2mm gauge between the copper and the beans allows mild heat to be reflected through the holes on the surface, rather than by direct contact.
These holes also create beans rest above the reflecting spots, with greater surface than solid drums.
This drum allows higher temperature roasting, faster process and excels in batch uniformity. It will suit anyone who wishes to roast blended or non sorted coffee, or just for those who wish to get the best as it is the most promising configuration of all.

Mahlkönig E65s

Filter Friday Episode. 3

Filter Friday Episode 2

Filter Friday Episode 1

Join Our Team

Title

Delivery Driver and Production Assistant (trainee roaster)

Reports To

Production Manager

Customary Hours

40 hours per week

Availability Required

Monday to Friday, with occasional weekends included. Must be able to arrange transport for early morning shifts, occasionally starting at 6am.

Position Summary

Are you interested in joining our team @ Silverskin Coffee?

This is a multi-tasking role in the delivery and production department of Silverskin Coffee Roasters. Primary driving duties include; delivering coffee to wholesale customers, organizing an efficient delivery route, troubleshooting any issues with wholesales customers on site. Primary production duties include; making coffee bags, bagging coffee, operating packing machinery, packing wholesale orders, warehouse stock management, weighing up green coffee. This is a great opportunity for someone with an interest is specialty coffee to develop his or her knowledge and skillset.

Required Attributes

Full clean Irish drivers license.
Experience in managing stock and performing regular stocktakes.
Experience as a barista to troubleshoot wholesale customer issues during delivery run. This is desired but not required.
Experienced with coffee machine and grinder operation to trouble shoot wholesale customer issues during delivery run. This is desired but not required.

Personal Attributes

An interest and passion for specialty coffee.
Patience and meticulous attention to detail, with a clear understanding of the importance of speed.
A desire to learn and expand specialty coffee knowledge.
Ability to work efficiently, diligently, and cheerfully as part of a team and also independently
Excellent at multitasking, prioritization, cleaning and organizing
Punctual

Rate: Negotiable

DO YOU EVEN PRE-HEAT GREENS

Okay not a very catchy title, but it’s a serious question. Not something I can take credit for either but something I can vouch for.

Way back in 2002 engineers from Probat had discussed the idea of re-circulating the air back from the roaster and using to pre-heat the green beans in the charging hopper. Just another big business cleverly saving money I thought but it’ll ruin the coffee.

The Therma two had two separate burners (a tangental and axial) and worked on a re-cicrulation model with negative pressure inside the drum (coffee roasted by convection) and a cool floating bed cooler (can you even say that?) Seriously the beans would float and dance in the air while cooling.

This has actually been done by Probat and can be viewed here http://www.probat.com/en/ecotech/green-coffee-preheating/

Anyway the idea never left me, the heating of the hopper not the dancing beans. When greens are “dropped” into the roasting chamber they cool the drums temp and bottom out until there is a ‘turning point” meaning the burner has been lit and the roaster bottoms out and starts to heart again.

So what would the effect of the heating the coffee be? Quicker roasts less body more development WHAT??

Cut to 2014 and a discussion with Vince Fedele from VST about channeling of all things. https://store.vstapps.com Vince asked me do you measure temperature of greens for winter or summer.

On the defensive I assured Vince that my profile changed one year ot the next, one season to the next. “I know what I am doing” I told him.

I hadn’t listen (ask my wife) however Vince suggested.

“Please note:  Many roasters routinely have problems with roast profiles especially at this time of the year – due to the change to colder weather.  The warehouse storing your green coffees are substantially cooler, and normal roasting profiles usually result in more under-development than during warmer months. If you log daily storage and starting temperatures throughout the year, you should be adjusting profiles as the weather and storage temps demand unless you are warming the green to a constant temp before loading into the hopper for drop.”

“Unless you either warm the green to normal room temperatures prior to roasting, (i.e., the same green starting temps as when you developed your roast profiles) or you develop new Winter season roast profiles, (i.e., hotter drop temps to compensate for the colder green) then your results may well lead to under-developed coffees, and one symptom of that is a change to grind settings (usually more coarse) as well as coffee cake flow restriction, and side channeling. This may be more noticeable on an 18g vs 20g or 22g, and should be cause for setting a flag.”

Logging coffees moisture and density sure, colour checking and again measuring coffee moisture and density pre roast sure but temp of green beans?

So I went and bought a Fluke infrared thermometer and began monitoring green coffee temp. Of course the temperature skews one season to the next.

What we found was if the been were cold upon charge the turning point was obviously effected and the problems Vince had expected.
We devised a crude but effective way of “heating” green beans effectively.

First with a mini cycle on the roaster with a pre-heated drum and no burner on but eventually heating in a steel drum with blow heaters.

This has us helped develop and use the same profile with same turning point, roast time, temps etc and an overall uniformity regardless of the season.

In 2018 we are taking this one step further, our operation is expanding and a temp controlled and humidified storage area will hopefully keep green coffee stable all year round!

 

Thoughts/Comments?

Pressure profiling. 

A little over a year or so ago I bought a pressure profiling machine for the roastery. Why? I hear you ask well why not. Seriously though with different roast styles a plethora of different beans, tampers grooming tools, distributors and grinder claims (all of which I love and exhausted) it was the natural next step.

The plan was to roast beans three different ways and trial them using the machine profiling them differently while furiously recording them in a notebook like I had something to prove.

This in a roundabout way did happen. I trialled light roasts with different profiles to medium roasts recording effect on TDS % different types of tampers for different types of roasts.

Anyway I got a little bit lazy and just started to drink coffee from the Elcor Vesuvius every morning.  What I’ve discovered is without any real scientific formula to shout about. Pressure profiling works. it does there I said it. Recently I acquired a Marzocco Linea mini for home (I know, I bought it not acquired it) now these machines sit side by side and I have to tell you for a light roasted coffee the results from a ramp up profile are far far superior to the flat profile of the paddle (switch driven) linea. How do I know, well I bloody well drink it every day. Everyday I reach for the naked portafilter from the Elcor and watch 1-3 bar slowly seep out then a step up to gradual 9 and a decline to 8. Tasting the same coffee in any other machine using the same grind, exact tamp (with puqpress) isn’t even close.

So there it is definitive scientific fact once and for all! Forget about the next big thing in coffee because it’s already here. Now I’m off to buy a GS3 🙂

SHIPPING COSTS

Shipping expenses have been a gripe on the webshop for the last couple of months so apologies for that. We have ammended the shipping:

€2.80 fon orders of €14 and below.

€4.60 on orders of €14 – €19.99

Free Deliveryon orders on €19.99

This is a trial while we work on pricing with a new courier company.

Thank-you,

Brian