Improving the Roasting Efficiency.

There are several aspects to be considered before a process can be implemented to improve a design.   Often it is possible to identify, let's say for the sake of discussion, 10 variables that will affect the process.  What is usually impossible to predict is the rank or the level of dominance of each variable unless you are really really really a gifted analyzer or clairvoyant.  Personally I resort to testing a few variables at a time to better understand their effect.  There will undoubtedly be surprises and inconsistencies when various variables are tested together but it is simpler to test in parts than in whole.

The testing results are unlikely to produce a clear graph such are joys of solving problems with multiple unknowns.  The results will give a better idea about the trade-offs that are required before a process can be adopted.  We maintained that coffee beans should be uniformly heated so that the chemical reactions that occur within the beans progress evenly.  It was also deemed important that the beans not be thermally overloaded.  To clarify; the bean has a certain capacity to transmit heat to its interior, if the heat applied is greater than what can be evenly distributed the exterior surface becomes much hotter  and creates a risk of scorching.  It is also for this reason that we roast at a relatively lower temperatures of 240°C to 250°C instead of ...  In "Espresso Coffee" R. Eggers writes the typical gas temperature of a drum roaster is 400° - 550°C.  The high temperature cooking analogy for beans hit by the super hot air is frying eggs while using the stoves highest heat setting.  Yet this fluidized bed roaster has a cycle time of less than 12 minutes versus up to 20 minutes in a drum roaster.   That  is Better Efficiency! 

The even distribution of heat is critical to preparing the beans for the roasting process.  We force heated air between the beans so that they are all heated, not just the outside layer.  There are small domestic roasters that also use air to create a fountain of beans.  It is quite dramatic but if the air flows through a narrow passageway then the remaining beans are not being heated until they gradually make it to the fountain.  Consequently, if you are looking for a home roaster look for one that pushes the air through all the beans.  Typically, the batch will move upwards as the beans are levitated by the flowing air then the air will break through and mix the beans.  The release of air pressure allows them to drop within the chamber but are then suspended again.  The air cushion has the added advantage of keeping the beans off the hot metal which often causes tipping which appear as little pieces of the exterior wall that leave behind a shallow cavity.

It is a simple concept that is regulated by many variables which turn it into a complex process.  

There is more to the efficiency quest than even thermal transfer and the recycling of air mentioned in the previous blog which leaves something to write about later.  Now it is time for an espresso.

Improving Roasting Technology

The picture links were removed because Photobucket decided to change the terms of usage in mid stream, so to say,  It is inconvenient for viewers but it is better to rid yourself of such people as soon as possible.  It is the attitude as much as the action.   We will try to repair that mess at NXTroasters.com

 The conventional approach appears to be - buy a roaster and endure its limitations.  Most conventional roaster owners spend more time developing marketing spin than improving their coffee roaster.   The deficiencies i.e. emissions are already the focus of some legislative bodies which require permits for roasters in their jurisdictions.   Oil burning engines, showing that blue smoke, are rarely seen on the road today yet many owners are complacent about roasting without pollution controls.

The roaster owners who are concerned that large plumes of smoke coming from their chimney are bad for their community image have purchased large gas fired after-burners that burn approximately three times more gas than the roaster itself.  Imagine if automobile pollution controls involved using three times more gasoline than the engine.

Rather than maintain the polluting status quo which may or may not have visible smoke, NXT Roasters Inc., have developed an alternative (branded the Roastaire in Canada) approach that uses the smoke generated as a source of roasting heat rather than expend large amounts of additional energy to thermally neutralize the smoke.   Both 15 Kg/hour concepts thermally treat the pollutants but one system uses a 400,000 to 700,000 BTU after-burner  to accomplish the task.

The first picture is of the main air passageway of a Roastaire after five years of full time roasting.  This revealing photo demonstrates the reason for their motto of "Clean Air Roasting".  This illustrates how efficient and effective the air is scrubbed clean as it is re-circulated during the roasting process.   This closed loop roasting process means that the air only has to be heated 20° to 40°C to return it to the roasting temperature.  Compare that to a single pass air supply that is continually heated from ambient temperature then sent to the chimney.   In "Espresso Coffee" R. Eggers writes the typical gas temperature of a drum roaster is 400° - 550°C.   What a wasteful process.

In comparison,

one drum roasters Maintenance Manual draws attention to the chimney,  "Even if residue build-ups do not exceed 1/8 inch (.3 cm) per year, clean system annually ".    The quotation is not properly cited nor acknowledged but I will do so if the manufacturer requests it.

They also have this picture of a drum roaster fan as a warning about the residue that coats some of their components.  Roast Magazine had the following quotation "It's not IF you're going to have a roaster fire, but WHEN."  Which roaster do you think requires the most maintenance?  Which type of roaster do you think was responsible for nearly 1,800 chimney fires in the USA in 2010?

Which roaster do you think roasted hundreds of pounds of green beans inside the exhibition hall of the last four annual 

Canadian Coffee & Tea Shows?

French Press Grind

The picture links were removed because Photobucket decided to change the terms of usage in mid stream, so to say,  It is inconvenient for viewers but it is better to rid yourself of such people as soon as possible.  It is the attitude as much as the action.   We will try to repair that mess at NXTroasters.com

The French Press is a classical brewer that has garnered many comments.  Often it is used for comparisons when authors are promoting a new device.   Many instructions and guides have been published yet there are recurring themes i.e. the medium grind with less than boiling temperature water.

Of course these demonstrations use freshly roasted coffee, otherwise what is the point of drinking coffee.

To the left the coffee beans were ground with a blade type grinder which is unable to attain the finer grinds.  The larger particles initially contain a lot of CO2 hence the large amount of foam.  I hesitate to call this crema because it is a mixture of foam and coffee grounds.

The foam develops very quickly when the nearly boiling water (that point will be argued later) is poured into the container.  Much of that is likely due to the sudden rise in temperature which causes the CO2 and other gases to rapidly expand, in the bean, when immersed in the hot water.

In the first minutes much of the coffee grounds are buoyed by the foam therefore they do not absorb sufficient liquid to decant.

Relying on the Mesh Plunger to do the solids / liquid separation will not give satisfactory results. Either the screen will plug with grounds and/or the screen  will deflect inwards let the ground migrate to the top of the mesh.

The argument that the grind has to be sufficiently coarse that the Mesh Plunger is not plugged ignores the importance of the extraction.  I maintain that the purpose of the Mesh Plunger is to keep the decanted coffee grounds on the bottom of the container when the coffee is poured into the cups.  The aim is to drink coffee not to have coffee grounds for breakfast.

The picture to the right was taken 1.5 minutes later.  We can see that the liquid line has risen but that more water will have to be added if the vessel needs to be full.  Very likely it will have to be filled twice to prevent the foam from overflowing.

In this case the Mesh Plunger was depressed 4 minutes after pouring the water.

                   
To the left is a coffee  ground with a  burr grinder using  a very fine setting which usually makes a variation of in the cup Turkish coffee.  The Mesh Plunger  only comes into play once the grounds have decanted.  The settling process is greatly accelerated by the fine grind which  yields grounds that have a high ratio of surface area to volume, hence a rapid and thorough extraction.

The crema, discerned from foam by the size of the gas bubbles, is similar to an espresso shot.  The brewing was well behaved therefore no water had to be added.  The brew decanted within seconds and was served sooner than the coarser grind.

The water was brought to a boil then poured over the coffee.  The comments about near boiling water scalding the beans must originate with manufacturers and distributors of machines that are unable to heat water over 85°C.  

The roasting chemical process is halted when the beans are cooled below approximately 150°C which hardly supports the claims that 90°C water scalds the beans.  On the contrary experiments show that the extraction is better developed at higher temperatures. 

Do your own experiments and note the observations.  If possible measure the temperature of the water for different extractions so that you can optimize your procedure.  In the meantime enjoy the fruits of your experiments.

Aeropress - Well Designed & Good Value

NXT Roasters has a Coffee and Aeropress bundle in limited quantities available at our Roastery.

The picture links were removed because Photobucket decided to change the terms of usage in mid stream, so to say,  It is inconvenient for viewers but it is better to rid yourself of such people as soon as possible.  It is the attitude as much as the action.

Freshly Roasted coffee enhances the Aeropress and vis versa.   This brewer does not require an electric brewer which may bring you better coffee since all decent kettles can boil water but not all electric brewers can deliver water at 90°C or higher.

The coffee is Freshly Roasted On-Site in a roaster of our design that has achieved new levels of consistency and pollution controls.  We are very proud of the taste.



 This is the Aeropress package which consists of the brewer and some handy accessories.  The previous blog links to two videos that demonstrate how to prepare coffee with this unit.

We have found that a fine grind enhances the extraction and quite likely gives you a better exercise.  It is difficult to establish if more calories are "burnt off" during the press.

There has been some controversy about paper filters versus perforated stainless steel discs in the domains of tasted and environment.  The stainless steel discs are nearly the price of the entire unit therefore we opted to make the bundle more affordable rather than a high end offer that would cause many to hesitate.

The coffee is less "strong" than an espresso but stronger than drip.  People adjust to their preference by adding water to the final brew and call it an Americano.

There is a challenge for those who appreciate the espresso because the Aeropress cannot be placed on a demi-tasse, well not yet.  Extracting a small volume into a large cup is not satisfactory so we must accept some limits.  However, before discounting the unit try what it does best which is a smaller cup of coffee.

Scoop:

The Scoop contains about 12 grams of coffee depending on how the coffee is scooped and packed.  The preparation of coffee depends more on consistency than an absolute number because other variables often compensate.  Just don't consistently use stale coffee - nothing compensates for that.

Funnel:
Might also be useful in the kitchen but in this case it helps assure that the caffeine deprived person gets most of the coffee grind inside the brewing chamber.

Stirrer:
This is used to be certain that the grind is dispersed in the hot water (remember the key word is hot).  The top has "wings" which prevent the blade from reaching the bottom and tearing the Paper Filter.  Of course this is a moot point when using the Inverted Method.



 Paper Filter:
This is placed inside the Cap to stop the sediment from reaching your cup.  The Paper Filter can be replaced by a stainless steel perforated disc for the people who feel that the paper absorbs essential oils that rightfully should be in their cup.















                          Brewing Chamber et al.:

                       Brewing Chamber                     Plunger                    Filter Cap                    Paper Filter

Inverted style brewing: This is mentioned first because everyone reads the instructions which illustrate the conventional way of using the brewer.

 Place the Plunger inside the Brewing Chamber. 

The internal volume increases approximately 60cc for every number the Plunger is pulled down. Therefore for those without a calculator:
- 60cc X 4 units X .03519 = 8.4 Canadian ounces
- 60cc X 4 units X .03381 = 8.1 US ounces

Unless you know all about compensating for the meniscus let's call it 8 ounces no matter where you live is the maximum capacity.

For a good Plunger seal keep both components vertical.  We cannot accept responsibility for spillage and "accidents" so we count on your diligence in keeping the hole towards the top.

Pour in the ground coffee without resting on the containers. Use one or two Scoops depending on the concentration your body requires.

Add the hot water without resting on the Brewing Chamber.

NOTE:  If there is unsteadiness or it is a challenge to manipulate these devices when they are full of scaldingly hot water you should resort to the conventional method.  Leave this method to the adventurous who thrive on danger.

Mix the water and coffee with the Stirrer to facilitate the extraction.

Place the Filter Paper in the Filter Cap (it will hold better if wet) and screw it to the top of the Brewing Chamber.  Hold the top of the Brewing Chamber.  Just remember the caveats - the liquid is very hot but bliss is now near.

Turn over the Aeropress and place it on a cup (please use a cup that is big enough for the contents). 

Push down on the Plunger.

It should now look something like the photo to the right.

Most people will now drink the coffee before extruding the Coffee Puck which is visible after removing the Filter Cap.

NXT Roasters has the Aeropress brewer

There are several brewing options available to the consumer but only a few have a "freshly roasted" priority mostly because they cannot deliver their coffee in a timely manner.

We searched  the Internet and wrote many emails to source the brewer that would give the best value to our customers.  The Aeropress is a well designed and built device which does not require an expensive electric brewer.

There are countless videos that address brewing with the Aeropress but most of them are not worth a mention because they exhort what I consider a faux pas i.e.
- advocating coffee is ok up to 40 days after roasting
- coffee should be used within 10 days of grinding
- a presenter attempts to explain how they defy the laws of physics by building unbelievable pressure
- another has concluded that the pressure pushing out the coffee is a vacuum
- for some reason some equate hot water with bitterness rather than improper roasting and staleness
Critical thinking is required on the Internet.  Yes, even now!

The Aeropress is versatile and has well designed accessories.  It can be used in two ways which are best explained by way of videos followed by pictures and explanations.

The KPCC Radio video demonstrates the Filter Down Method (photo to the left).  The temperature is important, it affects the extraction and should be above 90°C  (194°F).  The low temperature advocates probably make or sell machines that are unable to serve hot water.  The simplicity of the electric kettle is not to be scoffed at.  In an anecdotal observation a few tablespoons of coffee are placed on the bottom of your sink (especially appropriate experiment for those that have weeks old coffee but want to move to freshly roasted delights).  Allow some warm water to flow gently against the mini mound (gently - don't power wash it away) then increase the temperature.  You will find that the hot water dissolves while warm water agglomerates.

The Atomic Way video demonstrates the Inverted Method (photo below) which eliminates the dripping into the cup while mixing.

THE GRIND.  We often drink a modified Turkish style coffee where all the ingredients are mixed in the cup.  The finely ground coffee is only produced by a burr style grinder.  A finely ground coffee has a large surface area proportional to its volume which means a rapid extraction and that the grains soak up the water and decant quickly.  A fine grind like this creates a mini disaster in the gravity drained brewers because the water is poured onto the grind faster than the permeability allows it to go through, resulting in the dreaded overflow.  The plunger pressure in the Aeropress appears to circumvent that problem and yields a better extraction.

The end user has to determine the grind by experimentation.   A coarse grind will under extract and the water will be pushed through too quickly.

The Aeropress is then flipped over and placed

on a cup and the process continues as in the

conventional method.

FRESHNESS IS #1  The staling process starts after
roasting and begins to be detected at the end of one week.  Grinding the coffee accelerates the staling process.  The high surface area proportional to the content of a coffee ground means that it is more rapidly affected by oxygen and moisture.  Grind at the last minute.

More will follow shortly when the pictures of the various Aeropress components are taken or downloaded.

When Price is #1 Criteria ! (Who really pays ?)

A Purchaser is able to impose a price importance by choosing what is purchased based uniquely on the monetary cost.  Sellers quickly realize when a low selling price is required to make the sales.  Typically, "quality" is sacrificed to reduce the sellers cost while meeting a few important criteria such as appearance to a non critical eye.

Coffee beans do not visually change when way past their prime apart from having a little more surface oil.   That creates an opportunity for marketing spin that is analogous to a magic act.  The Purchaser may decide the price but the Seller decides everything else including the message that is crafted to give the Purchaser assurance that they received a premium product even when it is not.  In a magic show the spectator's attention is skillfully guided to the advantage of the magician so that the impossible is viewed as real.   The spectator does not suspend disbelief because they know that it is a performance.  Most spectators try to figure out how the magic was carried out.  For some reason low price marketing is not often subjected to the same analysis.

Economies of scale, low quality, and a magic presentation are fundamental to selling many products at low prices.  Foods with low or no nutritional value outsell fresh organic vegetables and are designed for the supply chain rather than the consumer.  The buying criteria are satisfied while other possible benefits are only implied.

Economy of scale can only be achieved with a wide network that can store and distribute a uniform product.  The supply chain optimized product, usually produced in one highly automated factory, to specifications that favour longevity or visual aspects .  The processing or transformation technology is optimized to fulfill the goals of the seller based on the buying criteria of the clients.  A great deal of research is undertaken to understand the buying decision and what common "markers" are used in reaching that decision.

The volume of imported roasted coffee is staggering.  This "Warehouse Coffee" does not reach the client while fresh but it does reach the end user while it is cheap.

My mantra is "Buy from a small batch roaster".   I prefer the freshest coffee over the exotic varietal that was roasted two or more weeks ago.

Updating our Roastery

We updated our Roastery and reception area so that it would not be confused with the workshop.



It is slightly more pleasant to sit down at a Granite table for the morning Espresso than a work bench.  Well, there is the optional bar height table for the devotees of the fitness club.

The main goal is to show that our roaster does not require a lot of room.   There is a full glass door that encourages observation though a full glass wall would yield a better view of the Roasting Theatre.

The coffee roaster is the focal point and the "raison d'être".  The green beans are loaded into the counter height Bean Loader Hopper.  the design of which expresses our opinion about overhead bean loading.  After roasting the beans are pneumatically conveyed to the Packaging area which saves the Roast Master from picking up roasted coffee from the floor area.  It appears that drum roaster designers just do not think of ergonomics and Roast Master comfort. These are important considerations when the Roast Master does sessions of over 20 roasts.

The previous post has some pictures of some of our morning Espresso shots.  Not all shots are photographed since pictures are secondary to tasting.  That series of pictures were intended to illustrate the Crema obtained with Freshly Roasted coffee.

The Coffee Roaster is labelled "Roastaire" which is the distributor for NXT Roasters in Canada.  Check out their site for information about roasting, energy conversion efficiency, and roasting pollution controls.

 

Maturing Espresso

The Espresso Transformation

Few people see the Espresso when it is all Crema.  You could be tricked into believing that it is an "air head".        Perhaps the roasting method deserves consideration but for now let's say that Freshly Roasted Coffee is the key which of course has to be supported by a well adjusted Espresso Machine.  This topic was also mentioned in a previous post.   The evolution is followed more closely this time. 

The first picture was taken 26 seconds into the extraction which continued for another two seconds.  The coffee is Cocamu (COCAMU is a coffee growers cooperative located in the district of Kirehe in the eastern province of Rwanda) roasted three days earlier.  The picture to the left was taken at the 4 second mark (after extraction).

 The Crema transforms into the liquid elixir.  The glorious description often depends on how badly the observer requires that first coffee.  The third photo, taken at the 11 second mark, is an indicator of the Crema to liquid conversion.  Unfortunately the graduated glass has rather coarse markings but they can be overcome by overlaying a grid on a printed picture.

 

Photo #4 is from the 20 second mark.  This is about when the client first sees the "magic potion".  Some may opine that a blend with a healthy Sumatran representation would be more appropriate.  That may be but it is outside the scope of this post.

 Photo #5, taken at the 34 second mark, is reasonably close to the typical serving time unless you yanked it out of the hands of the Barista which would only gain you three seconds and a frown. 

When are you served your Espresso?

This is Crema !

Crema !!
There are few "honest" ways to get great Crema.  The first one is Freshly Roasted Coffee in a tuned Espresso Machine.  Of course that is also how you maximize the sweetness of high quality Arabica beans.

The quantity of Crema rapidly decreases as the roasted coffee ages.  The taste is also greatly affected by the staling that begins to make itself noticeable within one week after roasting.

In the first two pictures the Arabica beans were roasted four days previously.

The crema to liquid coffee conversion starts towards the end of the brewing process it is not so fast that the client would be deprived of a significant amount of Crema.

Crema has been viewed by many as an indicator of freshness.  Unfortunately some people think that it is clever to deliver Crema without the freshness.  Common techniques are to add chemical foamers or to add Robusta beans to a blend of Arabica beans because the Robusta beans yield a greater amount of Crema even when it is stale.  At one time the Robusta beans were considerably cheaper but the price increased when too many people started to add Robusta to the Arabica beans.   Adding bitterness for the sake of looks is not a good trade - for the client.  

Though it is possible for anyone to add Robusta beans it is less likely when a roaster is serving freshly roasted coffee, because their brew will naturally have the great indicator of freshness.  After all, a local roaster does not have a long supply chain which requires months to complete the distribution process.

Do yourself a great "flavour" by sourcing beans from a local roaster or someone who can deliver them within 2-3 days from the roasting date.

The brew in this French Press was prepared two days after Roasting.  It is also significant that the beans were ground with a blade type grinder which yields a coarser ground that yields  impressive results but is inconvenient because water will have to be added and the particles take longer to decant.  If the Plunger is pushed too quickly the Screen will plug and a hydraulic lock will occur.                                                        

A burr style grinder yields finer and more consistent results.  The finer grounds will infuse more quickly and will decant reasonably quickly.  The screen is then pushed down to prevent the grounds from being poured into the cup.  The solids do not add to the pleasant experience.                                   

Develop a personal coffee ceremony to consistently get great results.  If the results are not the best then try one thing differently and note if it is better or worse.

Hopefully there will be many improvements because well prepared freshly roasted coffee is so sublime.