Sunday, November 11, 2012

Clever coffee filter

Clever Coffee Dripper
Not sure how new this device is but the it is called the Clever coffee filter, and for a one cup it is an interesting brew. Similar brew times to other coffee brewers, viz. 4 minutes.

See video here http://www.tested.com/food/coffee/5814-quick-look-at-the-clever-coffee-dripper/

Here is a review on coffee geek: http://coffeegeek.com/reviews/drip/cleverdripper/latest

Advantages:

  • One cup brewing
  • Filter style without a filter machine

Disadvantage:

  • is it is made from glass, not so portable.
  • Needs filter paper
  • Need a good grinder too.


Remember no matter what your brew fresh roasted coffee is always best

Wednesday, October 31, 2012

If you care interested in The Commercial Coffee market


The US coffee and tea manufacturing industry includes about 300 companies with combined annual revenue of about $9 billion. Major companies include Green Mountain Coffee Roasters (the inventor of the K-cup,  which Nestle copied to make the pods) and Farmer Bros, as well as divisions of the JM Smucker Company (Folgers), and Kraft Foods (Maxwell House). The industry is highly concentrated: the top 50 companies generate more than 90 percent of revenue.  

Globally, coffee and tea manufacturers generate about $70 billion in annual sales. The top green coffee producing countries (if you bulk together Robusta and Arabica Coffees) are Brazil,Indonesia, and Vietnam. Leading tea producing countries include China, Kenya, India, and Sri Lanka. Major companies based outside the US include Nestlé (Switzerland), Tata Global Beverages (India), and Unilever (UK).
  
Competitive Landscape

Consumer taste and population growth drive demand in the consumer sector, while economic growth of businesses, like restaurants and hotels, drives demand in the commercial sector. The profitability of individual companies depends on effectively managing raw ingredient costs, efficient operations, and effective marketing. Large companies have scale advantages in purchasing, distribution, manufacturing, and marketing. Small companies can compete effectively by offering specialized products or serving a local market The industry is capital-intensive: average annual revenue per worker is about $600,000.

Imports of roasted coffee and tea are 20 percent of the US market; exports are about 10 percent of US production. Part of the international export market is instant coffee.  

For more information please click on:
http://www.researchandmarkets.com/publication/k5c45l/coffee_tea_manufacturing

Relevance to Micro roasters?

If you are micro coffee roaster that concentrates on quality high grade coffee not sure this report has any significance. The largest exported of high grade or speciality grade pure Arabica coffee is Columbia, and they are hardly mentioned.

Saturday, October 27, 2012

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.

Tuesday, September 18, 2012

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.

Saturday, September 8, 2012

Coffee roastery AT Buiten roastery

Same coffee different roasts
Quality control when roasting coffee, is important. So lets look at how Quaffee is controlling Quality.
  1. Coffees are put through multiple roasting profiles regularly and then tasted using cupping and traditional brewing methods. This involves taking a single coffee and roasting it 3 to 7 ways and checking while profile tastes the best.
  2. Each time coffee is roasted the profile is logged:
    • Using a profile sheet that is captured
    • Saved in a format where every 15seconds we know the flame level, drum temperature and air flow.
  3. Colour and uniformaty is tested all the way during the roast and once the coffee is cool
  4. After a coffee is roasted it visually inspected, and any beans that produced flaws during roasting removed.
The importance is that if you are going to try and source high quality coffees, you need to respect the grower by making sure your quality of roast, is the highest you can mange, and that is what they are doing at Quaffee.

Saturday, July 14, 2012

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.bean scale scoop
  • 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.


Tuesday, April 24, 2012

Post Harvest Handling and Processing of Coffee

Repost of fao... There are additional notes added to that post based on our own knowledge of the processing of coffee.

1. The Coffee Tree

The coffee tree is a shrub with a straight trunk which can survive for about 70 years. The first flowers appear during the third year, but production is only profitable from the fifth year onwards. Botanists classify Coffee as a member of the Rubiaceous family. Of around sixty different species of coffee tree, two alone dominate world trade - the Coffee Arabica, or, more simply, Arabica, which represents 75% of production; and the Coffee canephora, which is commonly known by the name of the most widespread variety: Robusta.
Arabica is autogamous, that is to say, capable of pollinating itself, whereas Robusta is allogamous, i.e. needs other trees to pollinate it.

2. The leaves of the coffee tree

The coffee tree is an evergreen with spear-shaped leaves, which are green and shiny on the upper side. As with all Rubiaceous plants, the leaves grow in pairs on either side of the stem. The leaves of the Robusta trees are much larger than those of the Arabica.

3. The cherry

The cherry is the name usually given to the fruit of the coffee tree (Fig. 1). Green to begin with, the berries ripen over several months, becoming successively yellow, then red, garnet red, and finally almost black (this is the case for coffee that is Arabica typica, but some regions find it rippens at a dark orange).
The ideal time for harvesting is when the berries are red. The red skin is called the exocarp. Beneath the pulp (the mesocarp), each surrounded by a parchment-like covering (the endocarp), lie two beans, flat sides together. When the fruit is ripe a thin, slimy layer of mucilage surrounds the parchment. Underneath the parchment the beans are covered in another thinner membrane, the silver skin (the seed coat). Each cherry generally contains two coffee beans; if there is only one it assumes a rounder shape and is known as a peaberry. Coffee beans must be removed from the fruit and dried before they can be roasted; this can be done in two ways, known as the dry and the wet methods. When the process is complete the unroasted coffee beans are known as green coffee.
cross section of coffee cherry

4. Ecology

Coffee is a tropical plant which grows between the latitudes of 25 degree north and 25 degree south but requires very specific environmental conditions for commercial cultivation.
Temperature, rainfall, sunlight, wind and soils are all important, but requirements vary according to the varieties grown.
Ideal average temperatures range between 15 - 24 degree Celsius for Arabica coffee and 24 - 30 degree Celsius for Robusta, which can take hotter, drier conditions but does not tolerate temperatures much below 15 degree Celsius, as Arabica can for short periods. All coffee is easily damaged by frost, a danger either in southern Brazil or, closer to the Equator, at altitudes around 2000 metres.
In general, coffee needs an annual rainfall of 1500 to 3000 mm., Arabica needing less than other species. The pattern of rainy and dry periods is important for growth, budding and flowering. Rainfall requirements depend on the retention properties of the soil, atmospheric humidity and cloud cover, as well as cultivation practices.
Whereas Robusta coffee can be grown between sea level and about 800 metres, Arabica does best at higher altitudes and is often grown in hilly areas. As altitude relates to temperature, Arabica can be grown at lower levels further from the Equator, until limited by frost. All coffee needs good drainage, but it can grow on soils of different depths, pH and mineral content, given suitable applications of fertiliser.

5. Shading Protection

It was long thought that the coffee tree could not stand full sunlight exposure without damage, that is why early cultivation provided shade to the coffee tree resembling its natural habitat, forest.
Shade helps to protect the coffee trees from extreme winds and dryness. The ambient air temperature is uniform within the coffee trees making it cooler in the early parts of the day and warmer in the evening. The coolness, due to shading in the day reduces transpiration both from the leaves and the roots. Shade trees may also be used for erosion control on steep slopes.
Direct sunlight on the base of the plant can dry out and inhibit root growth, hence mulching and elimination of weeds is important.
The trend today is to use less and less shade but to supply the tree with increased amounts of both fertiliser and water. Under these conditions, they bear more heavily and still keep healthy.

6. Harvesting

The berries are ready for picking 8 to 9 months after flowering has taken place. In only two weeks, all the plantations in a region can be covered in cherries and it is then essential to pick only the ripe berries, which are shiny, red and firm to the touch. The unripe green cherries, mixed with the others, will make the coffee more bitter; those which have turned garnet-red, violet or black are over-ripe and give the final product an unpleasant, acrid taste.
The best quality is obtained by picking the ripe berries one by one by hand.

6.1. Four ways of picking coffee berries

  1. handpicking: is the most expensive method because it is labour intensive, but it also gives the best results. The ripe cherries are picked by hand one by one throughout the year as many times as necessary.
  2. stripping method: consists of removing everything on the branch by hand: ripe cherries, flowers, unripe cherries, and black, over-ripe ones. This method produces poor results, but is nevertheless practised in some African regions and in Brazil.
  3. combing method: combing of the branch with a special flexible comb. The ripe cherries fall to the ground, but the leaves and green cherries are left intact on the tree.
  4. mechanical method: uses either mechanical vibrators fixed to the tree trunks, which cause the ripe fruit to fall to the ground, or tractors with rotating brushes, which, unfortunately, damage the trees by stripping off the flowers and leaves as well.

7. Processing of the Cherry into parchment coffee

Once the cherries are harvested, the beans have to be extracted by using either the dry or the wet method. The wet method is more expensive than the dry method, but the coffee it produces has better quality properties.

7.1. Dry Method

The dry method (also called the natural method) is the oldest, simplest and requires little machinery. The method involves drying the whole cherry. There are variations on how the process may be carried out, depending on the size of the plantation, the facilities available and the final quality desired. The three basic steps, cleaning, drying and hulling, are described below.
Firstly, the harvested cherries are usually sorted and cleaned, to separate the unripe, overripe and damaged cherries and to remove dirt, soil, twigs and leaves. This can be done by winnowing, which is commonly done by hand, using a large sieve. Any unwanted cherries or other material not winnowed away can be picked out from the top of the sieve. The ripe cherries can also be separated by flotation in washing channels close to the drying areas. The coffee cherries are then spread out in the sun, either on large concrete or brick patios or on matting raised to waist height wire mesh tables to dry. As the cherries dry, they are raked or turned by hand to ensure even drying. It may take up to 4 weeks before the cherries are dried to the optimum 11% moisture content, depending on the weather conditions. On larger plantations, machine drying is sometimes used to speed up the process after the coffee has been pre-dried in the sun for a few days.
The drying operation is the most important stage of the process, since it affects the final quality of the green coffee. A coffee that has been over-dried will become brittle and produce too many broken beans during hulling (broken beans are considered defective beans). Coffee that has not been dried sufficiently will be too moist and prone to rapid deterioration caused by the attack of fungi and bacteria.
The dried cherries are stored in bulk in special silos or in bags until they are sent to the mill where hulling, sorting, grading and bagging take place. All the outer layers of the dried cherry are removed in one step by the hulling machine.
The dry method is used for about 95% of the Arabica coffee produced in Brazil, some of the coffees produced in Ethiopia, Haiti and Paraguay, as well as for some Arabicas produced in India and Ecuador. Almost all Robustas are processed by this method. It is not practical in very rainy regions, where the humidity of the atmosphere is too high or where it rains frequently during harvesting.

7.2. Wet Method

The wet method requires the use of specific equipment and substantial quantities of water (although modern methods, reuse this water by separating the fruit in to water and mulch, the mulch is used for composting). When properly done, the qualities of the coffee beans are better preserved, producing a green coffee which is homogeneous and has few defective beans. Hence, the coffee produced by this method is usually regarded as being of better quality and commands higher prices.
Even after careful harvesting, a certain number of partially dried and unripe cherries, as well as some stones and dirt, will be present among the ripe cherries. As in the dry method, preliminary sorting and cleaning of the cherries is usually necessary and should be done as soon as possible after harvesting. This operation can be done by washing the cherries in tanks filled with flowing water. Screens may also be used to improve the separation between the ripe and unripe, large and small, cherries.
After sorting and cleaning, the pulp is removed from the cherry. This operation is the key difference between the dry and the wet methods, since in the wet method the pulp of the fruit is separated from the beans before the drying stage. The pulping is done by a machine which squeezes the cherries between fixed and moving surfaces. The flesh and the skin of the fruit are left on one side and the beans, enclosed in their mucilaginous parchment covering, on the other. The clearance between the surfaces is adjusted to avoid damage to the beans. The pulping operation should also be done as soon as possible after harvesting to avoid any deterioration of the fruit which might affect the quality of the beans.
The pulped beans go on to vibrating screens which separate them from any unpulped or imperfectly pulped cherries, as well as from any large pieces of pulp that might have passed through with them. From the screens, the separated pulped beans then pass through water-washing channels where a further flotation separation takes place before they are sent to the next stage.
Because the pulping is done by mechanical means it normally leaves some residual flesh as well as the sticky mucilage adhering to the parchment surrounding the beans. This has to be completely removed to avoid contamination of the coffee beans by products resulting from the degradation of the mucilage. The newly pulped beans are placed in large fermentation tanks in which the mucilage is broken down by natural enzymes and can easily be washed away. Unless the fermentation is carefully monitored, the coffee can acquire undesirable, sour flavours. For most coffees mucilage removal takes between 24 and 36 hours, depending on the temperature, thickness of the mucilage layer and concentration of the enzymes. The end of the fermentation is assessed by feel, as the parchment surrounding the beans loses its slimy texture and acquires a rougher "pebbly" feel.
When the fermentation is complete, the coffee is thoroughly washed with clean water in tanks or in special washing machines. The wet parchment coffee at this stage consists of approximately 57% moisture. To reduce the moisture to an optimum 11% the parchment coffee is dried either in the sun, in a mechanical dryer, or by a combination of the two. The sun drying is done on extensive flat concrete or brick areas, known as patios, or on tables made of fine-mesh wire netting. The beans are laid out in a layer of 2 to 10 cm, and turned frequently to ensure even drying. Sun drying should take from 8 to 10 days, depending upon ambient temperature and humidity. Coffee dries more quickly if raised on tables because of the upward draught of warm air. The use of hot-air drying machines becomes necessary to speed up the process in large plantations where, at the peak of the harvesting period, there might be much more coffee than can be effectively dried on the terraces. However, the process must be carefully controlled to achieve satisfactory and economical drying without any damage to quality.
After drying, the wet-processed coffee, or parchment coffee as it is commonly known, is stored and remains in this form until shortly before hulling.
The final stages of preparation of the coffee, known as "curing", usually take place at a special plant just before the coffee is sold for export. The coffee is hulled, to remove the parchment, then passes through a number of cleaning, screening, sorting and grading operations which are common to both wet- and dry-processed coffee. Electronic sorting machines may be used to remove defective beans, including those known as "stinkers" (see aroma defects, 3.04), which cannot be distinguished by eye.
The wet method is generally used for all the Arabica coffees, with the exception of those produced in Brazil and the Arabica-producing countries mentioned above as users of the dry method. It is rarely used for Robustas. Figure 2, illustrates all the steps applied in both methods of processing.

7.3 Honey and other processes

There are other combination process that do a some wet processing, and some dry processing. One of these is called the honey method, where the skin of the fruit is removed using a wet method and then the remainder of the cherry is then processed as is done on the dry method.

coffee processing

Saturday, February 25, 2012

Coffee: To Freeze or Not to Freeze

When we first started getting asked about preservation of coffee, we did our own tests and our conclusion where that our coffee, roasted to an Agtron level > 50 or a Citi roast was able to retain its aroma and fragrance for approximately 2.5 months without any real loss, when kept in the freezer.

Since then we have had a number of clients and other so called ex-sperts saying now this is not the case.

Recently I found an article that was a little more scientific in its approach. I really believe it is worth a read:

You can read the whole article, but the conclusions are important:
http://www.home-barista.com/store-coffee-in-freezer-conclusions.html

Friday, February 24, 2012

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