Coffee Roasting in Cape town - About Coffee?

Coffee Roasting - is about roasting not brewing

The first so called Artisan, but what I would call micro roaster I ever met in South Africa, was Abul Bunna in 2003. They sold coffee beans at a market. Roasted coffee in a garage and spoke with passion about the bean.

Since then anyone running a coffee shop that wants to make an extra buck buys a roaster off the back of truck or that latest liquidity auction. I think the real roasters need to stand up and be counted. A coffee roaster sells coffee. A coffee roaster that is a coffee shop with an in store roaster, to make more money.

Brewing and Roasting are not related

The trend in cape town coffee world to use a roaster as a wow factor in a coffee shop should be an obvious red herring to anyone that can add 2 and 2.

Roasting of coffee should be brew independent. Yes there are some roast styles that suit particular brewing, but a roaster should roast a coffee and then see which brew style it suits. If you roast to sell coffee then how can your roast be independent of the way you brew coffee to sell it.

Coffee roasters should only roast

If you visit a coffee roaster, ask your self are they a roaster of a coffee shop? If they are a shop, then what is their product the coffee brew or the coffee roasted.

Roast Levels - how are they determined

The level to which a coffee is roasted is mainly determined by a few things

• The actual green coffee bean used:
  • The grade
  • The variety
  • The hardness
  • Where it was grown (shaded and highland grown is what we perfer)
• The Cultural background to coffee drinking

Bean Used

The lower the quality of a coffee bean the darker the roast has to be to extract any flavour out of the bean. One of the reasons for this is that the coffee taste comes mainly from the oils in the bean, and as you roast the bean darker more of the oil comes to the surface (it is actually pushed out almost). The better beans can be full of flavour at very light roasts. Also as you roast more of the sugars are converted to caramel. the darker the roast the more burnt the caramel.

At folk at Quaffee ensure that their coffee beans are roasted to a level where we have found them most tasty. This normally means past the first pop and no further than second pop starting. It is worth noting that the darker the roast the fresher the roasted bean has to be to fully enjoy it, since the closer the oils are to the surface the less they are protected from exposure and it is commonly known that oil exposed to light goes off quicker.

Culture

Culture plays an important part in the expectation of taste. Most cultures prefer a particular taste because it has become a tradition. The French dark roast their beans (about a 15), the Italians not as dark (about a 14). This is mainly because there is a belief that darker roasts decrease acidity. It does but it also decreases flavour, replacing delicate coffee flavours with an almost burnt toast taste. Most of Europe chooses the darker 13+ roasts. This may be related to the fact that although Europeans initially started drinking their coffees from the true source namely Africa, once the modified beans made it to Brazil, and the Robusta's were introduced in the 30's the only way flavour could be reached was to dark roast. We at Quaffee believe that these roasts are not desirable, and none of our roasts will ever go past 12, otherwise it is disposed of.

Third wave of roasting

The third wave of roasting is upon us. The first wave was dump flame and roast, the second controlled the roast a bit more, but still preferred the darker roasts the third is one that is profile driven and continually changing.

Things you need when setting up a roastery

Quaffee's new Diedrich IR-12 coffee roaster

We have been setting up a roastery at Quaffee's new location at Buitenverwachting. And thought it may be useful for others to note all the goodies we have required to do so. Besides obvious things like the roaster this is a list (as complete as memory serves to set up the roastery), and in no particular order:

• fire extinguisher
• ADSL line (for roaster, it is has an ADSL router)
• Natural fibre brush (for wiping down the coffee in the cooling bin)
• Micro fibre cloths (we got 5 but 3 should be enough). These cloths require little or no water to clean
• 1800 watt vacuum cleaner, get one that can suck and blow, give you flexibility
• Green bean buckets we got 2 for normal coffee, and 2 for organic coffee. For green bean you need about a bucket that can take twice as many litres and you can roast. So for us we got a 25 litre bucket, since it is a 12 kg roaster.
• Roasted bean containers. An make sure the are seal-able, especially if you are of the elk that believe in some ageing is required of the roast. Here you container must be at least 3 times the capacity of the roaster so in this case we got containers that could take 45 litre at least.
• Two scales (yes 2). One that can handle the green bean, and one for the packaging. If you have a small roaster that does 3kg or less, then you can get away with one scale. The bulk scale we got has wheels and can be moved. this is very useful. The reason for two, is the degree of accuracy. The packaging scale must work to the closest 1g, while the bulk scale 20g accuracy is good enough. Be careful to check this most of the scale sellers are not that clear with this.
• Black permanent marker and labels, to label the batch and coffee
• Roasting Sheets, that at least capture Date, Kgs Green, and Kgs Yield. There are a number of other items we recommend, but that is not for now
• Clipboard and pen, to capture date for the roast on the roast sheet above
• Packaging station  / work desk. Should be at least 90cm high
• Mulitplugs, are they not everywhere?
• Stools for sitting on during the roast
• Coffee scoops, the bigger the better, we got Espresso Supply's Rattleware Bean Scale Scoop, one white for organic one black for other. I think I would recommend 2 though.
• Zip lock bags, for sampling coffee, this is important to get the profiles right
• Mixing container. When making blends this is very useful, you can can get food grade mixers, but a container that has a tight seal is also fine.
• Crates of different sizes. We actually used a small crate to put the roasted coffee container on so that when the coffee is finished cooling we can dispense into the container without spillage. You can also use a small step.
• Packaging goodies, bags, lables etc (obviously)
• Container / file for filing the roasting sheets
• Dispatch sheet for listing what has been dispatched, especially if blending coffee.

That should get you going. Of course depending on your requirements you may need more.stuff. If we find we do I will list them here.

Chaff in you coffee?

sourced from the internet...

The long and short of it is...

THE SIMPLE ANSWER to this problem is airflow, airflow, airflow. The complication, however, is determining just where the airflow problem is originating: coffee, technique, weather, drum, blower, internal ducting or external ducting.

Coffee

Let's start with the coffee. Changes in coffee, or increases in the use of certain types of coffees, can significantly increase the amount of chaff. Brazils, Sumatras and Ethiopian Harrars come quickly to mind, especially if they are dry processed. The amount of chaff thrown off by any one coffee should not be an issue in and of itself, however this increases in the use of these softer-bean coffees necessitate an increase in the frequency of cleaning and general maintenance of the roaster. It is pretty simple, really: more chaff, more cleaning.

Furthermore, these coffees are the very ones where you will first notice this problem. They are not unlike the canaries in the coal mine. Because they produce more chaff, you are more likely to begin to notice airflow problems with these particular coffees. If you see this problem with these coffees and no others, you still have an airflow problem, and you will eventually see it with other coffees if you do not determine the cause and take the appropriate actions.

Technique

In roasters that use a single blower for both roasting and cooling, failure to move the damper from the cooling bin to the roasting bin positions can cause a reduction in airflow through the drum and may cause chaff to remain in the drum.

Weather

Weather-related problems primarily affect the least-experienced roasters, or those that have recently moved a roaster or changed an existing duct. Thermal inversions, abnormally strong or gusty winds, or winds from unusual directions can cause transient airflow problems with roasters. The best way to determine if you have an issue with weather is by keeping a roasting log and documenting your weather so that you detect any problem patterns. If you are experiencing transient weather issues, there are several things you may be able to do to lessen, or even eliminate, the problem depending on the particulars of that weather, your exhaust set-up and even the surrounding buildings. Permanent fixes include extending the height of your exhaust, eliminating horizontal exhaust terminations and changing the termination head of your exhaust. And, of course, if you determine that your problem was caused by highly unusual weather, you can always choose not to roast when that type of weather occurs.

Drum

Over-packing the drum can cause airflow restrictions that will not allow the chaff to be efficiently pulled off the coffee. Once again, you will see this most often with Brazils, Sumatras and Ethiopian Harrars. Additionally, the increase in bean size with darker roasts can cause an over-packing situation, even if the roaster operates well with that load size at lighter roasts. However, if this problem is appearing after roasting well for some time, then over-packing is not the cause, although reducing load size can produce a short-term solution.

Blower

The heart of drum and air roasters is the blower. It is the blower that provides circulation that allows for convective action — the dominant form of heat transfer in both air and drum roasters — and that removes smoke and chaff from the roasted coffee. For drum roasters, insufficient cleaning of the roaster blower is the single greatest cause of chaff remaining in coffee. This is true because drum roaster blowers move dirty air. This air contains coffee oils, chaff in varying degrees and green-coffee dust. If allowed to accumulate on the blades of the blower, these "dirty" elements will begin to reduce the amount of air that the blower can pull through the roaster. Eventually, there may not be enough airflow to pull the chaff out of the drum (this is also the greatest cause of smoke in the roastery). How often you clean the blower is mostly dependent upon five things:

• Type of blower (impeller or squirrel cage)
• Exhaust run (how much resistance your blower has to overcome to push out the exhaust)
• Type of coffees roasted (see above)
• Darkness of roast (the darker the roasts, the more blower cleaning that is necessary)
• Frequency of roasting (the more often you roast, the more often you need to clean)

Internal Ducting

Internal ducting is generally accepted to be the ducting between the drum and the blower, and may or may not include an internal chaff collector. External chaff collectors are considered to be part of the exhaust, except where the blower is mounted atop an external chaff collector. Many tabletop roasters are configured in this manner.

It is important that roasters understand how the air moves within their respective roasting system in order to know how, and how often, to inspect and clean this ducting. Many roasters clean internal ducting very infrequently — every year or so, depending upon the cleanliness of the blower. The dirtier you allow your blower to get, the likelier you are to experience a partial or complete clogging of your internal duct. Complete cleaning of this ducting can be a time-consuming and backbreaking task. If you are unsure of how this duct runs, the usual frequency of cleaning or how to clean it, go back to your manual or ask your manufacturer.

External Ducting

Improper ducting materials or poorly laid out external ducting runs are the second-greatest cause of poor airflow through restriction; ducting problems are, in fact, the greatest cause when roasters experience this phenomenon upon initial installation. Ducts that have too many angles, long horizontal runs, horizontal terminations, restrictive caps, or are the wrong size can all cause chaff to remain on the coffee by negatively affecting airflow through the drum. These types of ducting restrictions increase back pressure upon the blower, decreasing the amount of air that can be pulled through the drum. They can often be noted upon startup of a new, recently moved or re-ducted machine.

However, these types of restrictions are not always noted at start-up, but they will increase the likelihood of trouble in the future as well as increase the amount of maintenance that must be performed — especially cleaning of the roaster blower. Roaster ducts should be inspected, if not cleaned, at the same frequency as the main blower. When cleaned, they should be free of oils, chaff and dust. Mushroom caps, or any cap with screen, should be avoided at all costs. China caps should be modified to prevent the air from being pushed back down toward the open duct. If possible, all vertical ducting terminations should use a no-loss or low-loss stackhead (see Roast's September/October 2009 issue for more on this). Horizontal terminations should be avoided, if possible.

Most recurring problems with roasters come down to airflow issues. And chaff on coffee is no different. Perhaps the most important thing to remember about all airflow issues is that a problem in one area can cause connected problems in another. For this reason, it is important to understand the flow of air — both the flow through your roaster and through your stack. If not, you may find yourself fixing a problem only to see it recur very quickly.

One last thing

Make sure that the airflow in the roaster is cleanded out, this in itself can cause blockage and then the air cannot flow as it needs.

Thanks to Terry Davis