It is unlikely coffee roasting started by accident. Coffee does
not present itself to throwing the coffee beans in a fire, roast them,
and then make a drink. The coffee drink is an extremely
sophisticated brew. It was found early on in the coffee roasting
business that the coffee beans don't roast well if not moved around. If
the bean stays in contact with the roaster walls, the coffee bean
becomes seared. It taste burnt. Many of the early coffee
roasters which went over a fire were curved or global to get the
beans moving right when the roaster was shaken.
An additional little note: when one takes a tour of some of Americas old homes, the tour guide will point out pans with lids on them and claim they are bed warmers. May be? But, they are very old coffee roasters. Coffee roasting went on a lot in the 1700's and most people who could afford a bed warmer liked coffee. In those days they didn't have stores to zip down to and get fresh roasted coffee. What they got at a store was green coffee beans. These devices will warm a bed but they were invented and used for coffee roasting.
The next major roasting improvement came with the drum. This was
more or less driven by the need for more volume of roasted coffee beans.
Putting the coffee beans in a large mounted drum and rolling them made a
big improvement in volume. It was far easier to turn the mounted
drum than lift and shake the roasters.
The drum roaster was made in many sizes. However, for the most part, it remained the same for a long period of time. A simple drum with a sliding door mounted on bearings. All through the 1800's a simple drum put over a fire or oven which could be turned by hand worked well.
Then came gas and self coal contained roasters. The drum concept
held up well
but the source of heat changed. Gas and coal were easier to
manage in mass than wood so gas and coal coffee roasting drums
were prevalent in the late 1800's and early 1900's.
However, coffee is a unique food which the masses want. Price has always been a major consideration. Machines were made to meet every type of condition. Out in the wilderness, coal and gas were hard to come by. To say "expensive" would be understating the situation.
Next came electricity. Electricity allowed several things to
occur. Obviously, one change was the source of heat. Electric
heated drum coffee roasters quickly became popular.
Pollution became a problem. Even a hundred years ago, pollution was a problem. While the smell of coffee roasting from a small roaster may be attractive, living downwind from a large factory was not everyone's dream. Smoke was a problem in Europe during the 1800's. Thus, electricity was a major benefit.
Unfortunately, electricity was not everywhere. In fact, cheap
electricity is not everywhere even today. So, although
electricity as a source of heat may be too expensive in areas.
Therefore, price and availability still rules the market place
for an all electric roaster.
However, electricity as a form of heat source was so efficient
that it didn't contaminate the coffee bean with soot. This allowed a
screen roasting structure to develop which in turned allowed a
more even roast. Coffee beans were not seared by the hot drum walls.
Thus, a new concept was developed. This concept was heat the air
and force the air over the coffee beans.
This concept was used with gas too. Non sooting electricity may have started the convection air roasting idea but gas worked reasonably well. Nothing is sacred.
The biggest and most popular change in coffee bean roasting
electricity made was to remove the need for a person standing
around turning the drum. Here, the UNO roaster uses gas.
Coffee roasting devices have always been economic driven. If gas is cheaper than electricity, gas was used as a heat source. Heat source aside, labor is very expensive in its own right. Thus, a device which automatically turns the roasting drum without the need for a person is cheaper than a device which requires a person to keep the rotation up.
Not only did electricity reduce the labor requirement but it also
increased the drum load. Although the Vittoria roaster's drum was
turned by electricity, it used coke to heat the roaster. Here,
the drum motor is located under the cooling tray. One may also
notice, this is largely a cast iron machine. This ages it. Cast
iron went to steel. Steel is harder and lighter. Steel is
cleaner. Steel cost more.
Coffee roasting is still economics. For any given cost of heat, roasting a larger volume using the same amount of heat is cheaper. Cleaner is better because of safety. Besides coffee, everything was becoming big business. Large roasting facilities were being installed by corporations. If a small roaster was to
survive, they need to roast large quantities. Either size of coffee roaster, big or small, the firm hated law suits. Like everything at the turn of the 1900's, larger was better but lawyers gumming up the works was just as bad. Soon, safer was cheaper.
The modern age of roasters is very sophisticated. The
drum coffee roaster is well over 200 years old and is still with us today.
In the more modern world, bigger is better, but faster is better too. Coffee roasting temperatures went up, coffee roasting times went down. Again this is market driven. "Time is money."
One may also notice the meter and controls located at the rear of this machine. Temperature of the coffee bean in the old coffee roasters was guessed at by a master coffee roaster. Or, an armature coffee roaster, depending on the financial condition of the facility. The modern coffee roasting machines have Temperature controls so the system can turn itself off when the coffee bean is fully roasted.
One of the more interesting developments of modern coffee roasters is the automatic removal of the husk (Silverskin). Here, a Samiac shop roaster is fitted with a cyclone husk catcher.
The modern coffee roasters also have afterburners to dispose of the dust. This lowers pollution and the amount of complaints down wind.
Back to the concept of hot air roasting the coffee bean. This Paudal hot air coffee roaster has a capacity of 2 kgs. This device works on the principle of blowing hot air onto the coffee beans, thus keeping the coffee bean suspended in the air while roasting. The coffee beans fly around in
the front tube.
A temperature control in the hot air exhaust gives a close reading of the coffee bean temperature. The theory being that of known rate of thermal absorption will yield a known degree of roast. Heat is transferred proportional to the temperature difference. The larger the thermal difference, the greater the heat transfer. If the air temperature is known going into the roasting area, then if the air coming out is measured, the absorption rate being know, allows calculation of the bean temperature. Not very accurate, but close.
Although one may see the color of the coffee bean and roughly measure the coffee bean temperature, this technique does not yield consistent coffee bean roasts to a single decimal placement degree of roast.
The Wolverine Jet Zone Coffee Roaster is another hot air roaster. It
operates by blowing hot air down into the bottom of the coffee beans
which are in a glass container. The coffee beans are elevated by blowing
up the sides of the tube.
This is a very fast roaster. Typically, it roasts coffee beans in less than three minutes. The short roasting time preserves the acidity in Robusta coffees and lowers the weight loss. Theoretically, this allows better flavor extraction.
This again is an economic move because Robusta coffees are cheap. Also, shorter roasting times means a greater volume for a given time span. Generally speaking, these recirculating hot air machines saved money because heat was not lost to the atmosphere.
This device takes a long time to warm up and it has a very small capacity. I gains its volume by its speed in roasting. Due to its speed, it tends not to be exact. It could roast plus or minus a degree of standard or two. When one looks at the typical cheap coffee bean, one sees that the size and work effort going into production is not all that good. Thus, small coffee beans roast faster than large coffee beans making taste hard to control.
The
Roller Roaster is a hot air roaster.
The difference between this device and the others is the highly controlled individual bean. Well, sort of individual bean. While roasting, the hot air temperature is controlled in most all the modern roasters, but the air is injected into the coffee bean group. The coffee beans don't always migrate around evenly. In the Roller Roaster, the coffee beans fall down and enter a tube, the hot air forces the bean up through the tube and to the top of the bean pile. Effectively, the coffee beans are roasted one at a time.
A temperature probe measures the coffee bean pile temperature. This is not a calculated value based on thermal transfer. This is an actual real measurement.
Furthermore, this is an automated all electric device and it has husk catching cyclones. There are large and small models. This is a device which is designed for moderate to small sized coffee shops.
In factory roasting
, price is everything. The large coffee roaster roasts 500 pounds at a pop. One can not control all the variables when roasting by the ton all that well. In the coffee factory roaster which is shown here, the machine is computer controlled but knowing the setting is still guesswork. Close enough is good enough but it is wise to be very close the first time. Mistakes are very costly. The Roller Roaster is used to predetermine the computer settings prior to making a run on the big machine. $40,000 worth of test equipment is used to figure out the settings on the big machine. Then it is a matter of pouring the coffee beans in one end and shipping the boxes of bagged ground roasted coffee at the other end.
It is the small shop which attempts to regulate taste.
One last thing about fresh roasted coffee beans. They gas. Many vendors advertise fresh roasted coffee. But, seldom ship fresh roasted coffee. The coffee bean easily gets stale. At the very least, the taste changes with aging. A simple cheap way of not worrying about fresh roasted coffee bean gassing is the let it sit till the gas expels itself completely from the roasted coffee bean.
A simple way of telling if your vendor ships fresh roasted coffee beans is looking at the packaging. If the packaging has a one way valve, then there is a good chance the coffee was freshly roasted. If there is no one way valve, there is no chance the coffee was freshly roasted. The gas pressure is sufficient to blow up a tightly sealed common tin coffee can. The one way valve allows the gas to leave the container and air not to get in.
Another way: As soon as you get the roasted coffee beans, take them out of the bag and put them in a sealable plastic ziplock bag. If the bag expands, then the coffee beans were fresh. If not, then they are old.
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