Evolution history of bean baking machine

Household baking utensils

At the beginning of the history of coffee, there were only household bean baking utensils in the world. These bean baking utensils were standard accessories in ordinary people's kitchens until the early 20th century.

Sixteenth century: Iraqi baking pans

This simple construction tool mainly moves the pot to a heat source on a small fire or coal fire and is supported by a two-legged stand on a long handle. The bottom of the pot is perforated and caffeine beans are stirred with a spoon on the side during baking. According to coffee historian William Ukers, this type of baking utensils were used in Iraq in the 16th century.

Eighteenth century: American stove bean dryer

These three devices are the most typical bean baking utensils used in American families in the 17th and 18th century, in which two round-bottomed pans with feet are called "Spiders". On the other hand, the long-handle cylindrical bean dryer at the bottom is the predecessor of most coffee shops and commercial bean dryers. At one end of the cylinder, the pointed part is used to insert a hole in the fireplace to fix the position of the cylinder. After that, it is convenient for the baker (at that time, it should be the servant or child of the family to rotate and operate the equipment. At the back of the cylinder, there is a sliding cover design, that is, into the mouth of beans.

Circa 1860: American furnace roaster

These bean baking devices are designed to be placed on an open stove (whether burned with wood or less coal). In the mid-18th century, this kind of bean baking device was only used by the high consumer class. Families that were once less well-off or less popular still use the usual iron long-handle frying pan to bake coffee beans, which can also be used to cook other foods.

Early 19th century: Italian alcohol lamp-style bean dryer

The glass cylinder of the bean roaster, which can be used as a display on the table, makes it easy for operators to observe changes in the color of coffee beans during roasting. The device relies on alcohol lamps to provide heat.

Early 20th century: electric household bean dryers in Europe

The heat source of this bean dryer, which can be operated on a general table, is provided by an electric heating element located in the bottom base. Although the practice of baking at home declined at the beginning of the 20th century, such household bean roasters are still on sale in Europe and Japan.

1980s: household electric heating air-flow bean baking machine

This small appliance is an intelligent crystallization of the principle of air-flow baking, which is elegant and easy to use, and because the development of this principle has revived the trend of roasting coffee beans at home. This kind of machine works as follows:

There is a blast of hot air blowing upward at the base of the machine, while roasting and stirring the coffee beans in the narrow baking chamber, which is the "neck" part of the machine in the picture. The "head" position at the top of the machine, its function is to separate the silver skin from the air and collect it so as not to fly around. The machine in the picture is called "Aroma Roast" and was introduced by Melitta Corporation from Hong Kong in the 1980s.

Early 21 century: household electric heating air flow bean dryer

At the turn of the 21 century, many small household air-flow bean dryers appeared one after another, and these forms of home air-flow bean dryers have made some improvements to the shortcomings of Aroma Roast bean dryers. The Fresh R Europe ast bean dryer in the picture is the benchmark of all these household air-flow bean dryers, and most of the other models are inseparable from this structural design:

1. The heater and fan in the base at the bottom of the base blow the heated air to the upper room baking room.

two。 The baking room is made of transparent glass, which is easy to see.

3. Hot air can simultaneously bake and stir coffee beans in the bakery.

4. There is a silver collection device in the shape of a hat at the top of the baking room.

5. A timing knob can automatically turn off the power of the heater, but keep the fan running and blow cold air at room temperature into the baking chamber for cooling.

Early 21 century: convection heat type bean dryer

The Zach&Dani's Gourmet Coffee Roaster ingenuously designed an effective device to filter out the baking soot, finding another way out for the biggest problem of the home bean baking machine. The structure of this bean baking machine is as follows:

1. There is a spiral blender in the center of the baking room, which can stir the coffee beans inside.

two。 The hot air blown by the base does not need to be too strong, which is different from the general air-flow bean dryer, which is only responsible for baking function and not stirring, so the overall baking time will be prolonged. By prolonging the baking time and weakening the airflow intensity, the baking dust can be reduced.

3. In the case next to the glass baking chamber is the catalyst converter, which can filter out the baking soot emitted from the baking chamber very efficiently.

Bean dryers for cafes

Coffee shop bean dryers, retail bean dryers, and small bean dryers are all medium to small bean dryers, which are often used in coffee shops during wartime. Before the early 20th century, most of their coffee beans were made by bean roasters in such cafes, as long as they were not baked at home, but by the early 1950s, large baking plants and pre-ground packaged coffee beans were popular. By the end of the 20th century, when coffee shops were making a comeback with bean roasters, consumers in the United States and other industrialized countries rediscovered the joy of carefully roasted fresh coffee beans.

Eighteenth century: bean dryers used in American cafes

This bean roaster was probably used in the cafe at that time. This bean dryer is an improved version of the bean dryer for household cylindrical fireplaces in the 17th and 18th centuries. it is also a very simple structural design. The whole bean dryer must be placed in the fireplace and placed on the residual fire, while turning the cylinder by hand.

Eighteenth century: bean dryers used in British cafes

The bean dryer in the picture has two more improvements to the design of the fireplace bean dryer:

1. The bean dryer itself has a built-in heating source, and coal can be burned at the bottom of the drum to provide heat energy.

two。 A cover is added to the drum of the bean dryer, so that the heat energy inside the drum can be distributed more evenly.

1862: bean dryers in cafes in the United States

The design, first made in 1862 by E.J.Hyde of Philadelphia, was a typical design of a bean dryer in an advanced caf é in the mid-19th century. This bean roaster is designed to pull the baking drum out of the fire to facilitate the cooling of the roasted coffee beans. In addition, a mixing blade is designed inside the drum, which can promote the rolling transposition of coffee beans when rotating the drum. In this era, the heat source of the bean dryer is still built-in coal fire at the bottom of the drum, and the drum is still rocked by hand.

1890s: French gas fire bean baking machine

According to coffee historian William William Ukers, the world's first patented gas coffee roaster was first seen in France in 1877. Until today, roasted coffee beans from gas sources are still the mainstream all over the world. The Watts-fire bean roaster in the picture was patented by M.Postulart in 1888. The baking chamber was still spherical in part. At that time, Germany, Britain and the United States had already taken guns to the round-shaped bakery. France is the only country that is still loyal to the spherical bakery. The roasted coffee beans are poured out of the spherical baking chamber by the principle of gravity and entered into the lower drum cooler through a loophole. After cooling, they are poured directly into the bottom drawer.

1907: bean dryers are used in German cafes

In the picture of this Perfekt bean dryer made in Germany in the early 20th century, the pulley drive belt on the left side of the outside of the machine is the structure that drives the rotation of the drum, and it is also through some gear structures (which can only be seen clearly from the right side of the bottom) to indirectly drive the mixing blades in the cooling plate. The function of the stirring blade is to stir the coffee beans and improve the cooling efficiency.

The heat source of this bean baking machine is gas fire, and there is an exhaust pump at the base of the machine, driven by a belt on the left side of the outside of the machine, which blows heated air into the baking drum to circulate, thus ensuring a more uniform baking result. and effectively shorten the batch baking time, not as time-consuming as the old bean baking machine which only relied on heat conduction. This hot air stream also plays the role of bringing out the baking smoke and silver skin (a layer of film attached to raw coffee beans); finally, there is also an exhaust pump blowing fresh cold air at the bottom of the empty cooling plate, which works with the mixing blades in the cooling plate, the cooling efficiency is greatly improved.

In such a bean roaster, the tool to detect the baking depth is to make a small hole in the front of the roaster and insert a long "Trier". The sampling rod can go deep into the coffee bean pile in the baking process to obtain a small number of coffee bean samples. The coloring depth of these samples is the basis for the roaster to judge the timing of the beans. Once the roaster decides it is time to drop the beans, the roaster can pull up a lever and press it. Open the bean mouth, and the roasted coffee beans can be poured out to the cooling plate.

Although there were new electronic devices and many improvements in roasting technology in the 20th century, this bean roaster and other similar machines remained the mainstream of small-scale coffee roasting throughout the 20th century.

Early 20th century: bean dryers for German-made small cafes

In Germany and other European countries in the 1920 and 1930s, streamlined, space-free bean dryers like the one pictured here are often displayed by cafes on the front door or windowsill, and attract the attention of passers-by with the smell of baking. The working principle of this bean baking machine is almost identical to that of the aforementioned machine.

1980s: bean dryer for airflow cafes (internal section)

The air-flow bean roaster heats the coffee beans with the same hot air flow and stirs the coffee beans at the same time (let the coffee beans move in the way of gas). In the air-flow baking model designed by American Mike Siewicz, the heated hot air is blown from bottom to top through the sieve at the bottom of the baking chamber, which can drive the coffee beans up along the wall of the baking chamber and fall down at the top. Then there is a fountain cycle over and over again, and the position of the temperature probe part of the thermocouple thermometer can roughly measure the temperature of the coffee bean pile in the baking room. it is easy for the roaster to judge the timing of the beans according to the temperature point rather than the apparent chromaticity. The roasted coffee beans will be directed to another separate cooling chamber and cooled with cold air at room temperature.

In the past 50 years, there have been many other types of air-flow bean dryers, whose basic structure and working principle are more or less the same, only when coffee beans are stirred in the hot air flow mode. many air-flow bean dryers have added bean viewing windows or changed to use glass tubes as baking rooms, adding some interest to the originally ordinary foreign trade. On the other hand, the small air-flow bean baking machine even brings the automatic control technology into the baking control, so that the bean baking machine can be guided by electronic devices after the thermocouple thermometer reaches the preset target temperature value. automatically cut off the power to the heating part of the baking.

Large-scale industrial bean dryer

After the American Civil War, coffee beans sold in packaging on the display shelves of major cafe systems were first introduced. By the end of World War II, the mainstream commodity in the North American coffee market was pre-roasted beans / pre-ground coffee powder produced by large roasting plants, and this kind of high-volume roasting technology, which demands centralization and standardization, was called "coffee bean roasting plant" (Roasting Factory/Plant) or "commercial bean roaster" (Commercial Roaster). In the middle of the 19th century, large roasting plants in the late 19th century were just enlarged versions of bean roasters used in cafes, but at the end of the 19th century, the first "continuous bean roaster" (Continuous Roaster) was developed, which could roast coffee beans one batch after another without stopping.

1848: British industrial bean dryer

The large bean dryer in the picture is called "Dakin bean dryer". This is aimed at the improved type of American "Carter pull-out bean roaster" (Carter Pull-Out) introduced on page 35. The drum driving force of this bean roaster is the same as Carter's bean baking machine, which is driven by steam pulley, and the baking room is completely wrapped in a brick fireplace. But the Dakin bean roaster is different, the first is that there is a second layer of metal shell on the outside of the baking drum to block direct heat, and the second is that the "pull-out" design is more elegant and beautiful than the Yangchun design of the Carter bean baking machine.

1864: a small industrial bean dryer in the United States

Jabez Bures launched this continuous bean roaster with "double helix blades" (Double-screw) in the drum in 1864, which allows the coffee beans in the roasting drum to move forward and backward. This initiative not only makes the distribution of coffee beans inside the drum more uniform and stable, but more importantly, the next bean mouth is opened. It can also efficiently push the roasted coffee beans (the beans at the front of the drum) out of the mouth of the beans. In the 20th century, most drum baking machines used a design like this, which made the bean program faster. At this time, the outside of the baking drum is still covered by a brick fireplace, and the driving force is still steam.

End of 19th century: French bean dryer for gas and fire industry

The new coffee bean roasting technology, which uses gas as the heating source, was developed in the decades at the end of the 19th century. The lower bean mouth of the legal machine in the picture is located directly below the drum and the coffee beans are pulled by natural gravity into the cooling plate.

At the end of the 19th century: gas-fired continuous bean dryer in Germany

The Thurmer bean dryer developed in Germany in 1893 is probably the first gas-fired continuous bean dryer in the world. In the long baking drum, there is a set of spiral blade design, which can guide the coffee beans in roasting to move in an one-way way. when the coffee beans reach the end of the drum, they are already baked, so, in such a bean roaster, raw coffee beans can be continuously poured into for continuous baking. It is also a very practical design concept that this principle is applied to the "batch dryer" (Batch Roaster) and the bean dryers used in cafes in the past. The Thurmer bean roaster also introduced the concept of Fast Roasting (a batch within three to four minutes), which was immediately welcomed by large-scale baking companies, but so far, the quality of fast-baked coffee beans is still controversial.

End of the 20th century: continuous bean dryer (internal section)

The section view shows the latest continuous bean baking mechanism, which can see through the internal structure of the baking drum. The heat source of baking is provided by the strong heated air flow on the left side of the baking drum, which is blown to the right through the drum, and the baked caffeine beans are transported to the end of the drum and cooled by a stream of cold air and water mist. Today, however, more and more large continuous bean roasters use air flow baking, which is not far from the air flow roaster (Sivetz Shop Roaster) in the Siviz cafe introduced on page 55 (only a bit large): when a batch of coffee beans are roasted in hot air, they are sent to another tank for cooling. Then pour a new batch of raw coffee beans into the baking room to continue the next batch of baking process, repeating this cycle over and over again, so that it can be called "continuous baking".