ROASTMAXTOR IS BUILT TO THE FOLLOWING IDEA.

HOT AIR

In RoastMaxTor the hottest component is the air, nothing is hotter. This means that we can roast precise to the degree. In conventional roasters the hottest component is the metal just like a cooking pan. There is no way out you will scorch the beans, resulting in several roasting profiles within a single bean.

RoastMaxTor roasts coffee beans in fresh air. The fresh air going through the beans is approximately 2 m3 per minute. No smoke is present in the roasting chamber unlike in conventional roasters. Smoke has taste, think of smoked fish or meats.

For any green coffee bean, the profile of the aromas is determined by specific conditions of chemical reactions, controlled by the roasting parameters.

Meaning the roasting temperatures have a great influence on the bean temperatures, the dehydration, the pressure build-up, the colour change and the development of key aroma compounds.

Most aroma compounds register the biggest increase in concentration at the medium stage of dehydration where the water contained in the beans range 7 to 2%.

Varied time-temperature profiles lead to distinct aroma compound configurations.

To produce a specific flavour the precise control of roasting time, supply temperature and product temperature is needed.

The mode of direct heat transfer and temperature are the most critical features in the process.

RoastMaxTorcontrols the temperature that is applied by the heater during the roasting. It also controls the Pile temperature (hot air and bean mixture temperature).

Why are we measuring pile temperature?

This is the closest you can get to bean temperature.

In research bean temperatures are taken by drilling a hole into the beans and inserting super small thermocouples to gain ratios between surface and core temperatures. Hardly to be done in real life.

WE KNOW WHAT MAKES A GREAT ROAST.

If we achieve to have the same colour all the way through the bean from surface to surface.

However, surface temperatures vary from core temperatures. Let’s say set pile temperature is 210 degrees, depending on amount of beans roasted the beans will reach a surface temperature of about 200 degrees within let’s say 2 minutes. Then the core temperature will be maybe 120 degree. The interesting part is that it will take a lot longer for the core to reach 200 degrees. Once core temperature has reached 200 degrees surface temperature again has increased but the difference is only maybe 10 degrees. As the pressure inside the bean increases until the temperatures overcome the vaporization temperature the remaining water in the center of the bean evaporates. Evaporation is spontaneously in an endothermic flash and creates a slight drop in temperature. The slower, you go through this stage, the less damage you do to the bean. After that happened the bean can roast all the way through to the core.

A big factor is temperature transfer. Example, if it is minus 2 degree outside that is cold, but if it is minus 2 degree and windy that feels much colder. You have no heat to keep; it is blown away from you. This also applies to heat. Fast moving hot air has a much higher heat transfer rate than slow moving or still hot air. Imagine hot wind in a sauna.

Hot air roasters have a much higher heat transfer rate than conventional drum roasters. The high air to bean ratio ensures a more rapid heat transfer. This is one of the reasons RoastMaxTor achieves the same result in half the time. The game has changed; higher heat transfer heats beans more efficient. The core of the bean is faster at first target temperature and can roast at exact temperatures that are favourable to develop aroma compounds.

To roast beans evenly a steady increase of temperature is best. Still it is also important that the inner pressure of the bean is generated to develop enough aroma components. Gases, mainly CO2 and CO, are developing during roasting. They are trapped in the bean and lead to pressure build-up. Gas development and bean pressure is effected by the roasting temperature only. Bean pressure can be 15 to 25 bar during the last stages of high temperature roasting. Pressure is another reason that influences not only the bean micro structure, but also the circumstances for chemical reactions.

The water in the beans evaporates and cools the environment temperature. The difference between supply temperature (air going into the roaster) and the pile temperature is as great as 40+ degrees and in the beginning stage even more. It is important that the bean has the time to get rid of water content right down to the core. Therefore a slow but steady increase in heat is important to achieve wanted aroma development. If the temperature increase is too fast and hot, the coffee has no time to develop enough of certain aroma compounds. Like Methional which represents sweetness like in boiled potatoes, or 2,3-diethyl-5-methyl pyrazine which represents Musty Nutty Vegetable Roasted Hazelnut.

A good roast would start up with about 190 degrees environment temperature (preheat temperature). That would drop after filling of the beans to about 130 pile temperature. There should be a steady and continuous increase to up to the wanted degrees of pile temperature. At medium pile temperature the aroma formations are the highest so it is necessary to roast into these ranges. High pile temperatures above 238 cause an unfavourable aroma profile. The roasting colour should not be too dark as aromas degrade right there, and the coffee is thinning out. As for espresso roasting, a slower build-up of temperatures with a longer roasting time will be the best. Espresso should not be roasted into second crack, which occurs at about 230 to 236 degrees. For the sake of degrading Trigonelline which is bitter and water-soluble and will end-up in the cup, espresso roasting can go up to 230 degree pile temperature.

However after reaching the first target temperature RoastMaxTor can drop temperature within a second to a suitable supply temperature that would benefit the aroma and compound development, and that is unique.

WHAT ARE THE DIFFERENCES BETWEEN AIR AND DRUM ROASTER?

Most Drum Roasters are secondary heating systems, meaning that, a heat source heats the drum and the drum heats the beans. The drum is always hotter than the beans this results in different temperatures within the roasting environment. Beans that are in contact with the Drum are scorched and have therefore different roasting profiles within the same bean (outside darker than inside). A Drum Roaster roasts at a constant increase in temperature and then drops the beans at the wanted temperature or colour whatever the system. A drum can decrease temperature only slowly and not to a certain degree of supply temperature. To drop Temperature in a drum roaster you have to reduce heat and increase airflow. But where is it going to stop? Today there are drum roasters available that also utilize only hot air for the roasting process which is a much better alternative to the conventional drum. I am not saying that these coffees cannot be excellent to drink, but I am saying that there is a lack in process control, and every batch is different. A Roast Master has to be present always to control all aspects of roasting.

RoastMaxTor is an air roaster, also called fluid bed roaster. This is a direct heat system meaning, the hot air directly heats the beans and nothing is ever hotter than the pile temperature, even the glass roasting chamber is never hotter than the pile temperature. There is no scorching and the roast profiles of the beans are the same colour all the way through. After we have achieved the first target temperature we can drop the supply temperature within a second as all is controlled by one heating element. Therefore air roasters are the only option to do profile roasting with a 100% process control. You might say why would you want to drop supply temperature? Let me give you an example for an Espresso Roasting profile.

Looking at the above profile working this on a drum is not possible with a variance of 0.5 degree.

Most laboratories use fluid bed roasters to do their testing. Even big coffee companies use them to work out their roasting profiles for the big drums but they seldom achieve in the drum what they worked out in the fluid bed.

Please consider this:

WE ROAST COFFEE IN FRESH AIR!!!

There is never smoke on the beans and in drums there is always smoke on the beans. Smoke has taste as we know. Sashimi or smoked salmon? Air Roasters don’t have all the smoke, tar and carbons added to the product roasted in drums in some drums more and in some less.

ROASTMAXTOR IS A ROASTER OF THE COMPUTER AGE. Although it takes some romance out of the roasting computerized roasters can produce consistency  batch by batch.  Man can only do so much and timing is crucial when it comes to roasting coffee, that’s not a secret