Professional coffee roasting | Analysis of special terms and acronyms for coffee roasting

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I hope it will be of some help. The explanation and demonstration of these nouns are scattered in dozens of articles previously written.

BT- Bean Temperature: the temperature measured by a temperature probe deep into the bean pile, which is the comprehensive value of the temperature between the surface of the bean and the air around it.

Furnace temperature / ambient temperature (ET- Environment Temperature): measure the temperature detected by the temperature probe in the baking chamber. In the case of a drum roaster, its position is usually in the relative position on the other side of the bean temperature probe and will not come into contact with beans. Some bean roasters do not have a furnace temperature probe, and the temperature of the exhaust probe (exhaust air temperature ET- Exhaust Temperature) of the roaster is taken as the furnace temperature / ambient temperature.

Incoming air temperature (Inlet Temperature): the temperature probe (temperature control) is usually set in the hot air baking machine. If the designed hot air effect is relatively large (for example, more than 70%), the semi-hot fan will also be installed for the bean baker's reference. The incoming air temperature represents the hot air temperature entering the baking room, which is a kind of air temperature.

Exhaust air temperature (ET- Exhaust Temperature): the hot air temperature leaving the baking chamber, the position of the probe is near the exhaust fan at the outlet of the baking tube or the rear end of the exhaust duct, which is a kind of air temperature.

RoR- Rate of Rise of BT degree: the degree of rise and fall of bean temperature per minute (usually, but some software is calculated in 30 seconds)

Furnace temperature rise rate (RoC-Rate of Change of ET): the degree of rise and fall of furnace temperature per minute (usually, but some software is calculated in 30 seconds)

Maximum ambient temperature (MET- Maximum Environmental Temp (max exposure temp during roast)): a common term on the home-barista forum. It literally means the highest ambient temperature in the baking process, which varies with the baking process. It refers to a place in the baking tube that does not touch the beans, which is usually the place where the baking ambient temperature is highest, such as the exhaust outlet of the baking tube.

When Crash-beans enter an explosion, RoR drops sharply, which is inferred to be affected by a large amount of moisture burst from beans in a short time.

After Flick- beans entered an explosion, RoR rose sharply under the condition of maintaining the same firepower, which is speculated to be caused by intense exothermic reaction.

Temperature recovery point (TP- Turn point): after the roaster is preheated, the charge bean temperature will begin to drop until the temperature begins to rise after an equilibrium point, and the point before heating (time, temperature) is called the temperature recovery point.

Pressure difference: a pressure difference measuring point is installed in the exhaust air pipe to measure the pressure difference between the exhaust pipe (or inside the baking cylinder) of the roaster and the outside world through the pressure difference measurement, in Pa. In the case of a passively ventilated drum roaster, the stronger the exhaust, the greater the pressure difference (that is, the smaller the pressure in the cylinder).

Air-to-Bean Ratio (ABR wind weight ratio) = total weight of hot air used in baking divided by total weight of raw beans = Air weight (kg) / Bean weight (kg)

Soak: the operation of flameout or small fire to average temperature, return temperature or 100C or a certain firepower lifting point after preheating of the bean dryer.

AUC (Area-Under-Curve): the surface meaning is to calculate the area under the bean temperature curve, which is intended to represent the use of energy during baking.

Baked coffee: coffee that has been slow-baked for a long time, with a dull aroma of toast, or a not-so-fresh cardboard flavor

Baking rhythm: with the same total baking time and baking degree as the premise, the trend of bean temperature curve during baking can be divided into

FSSF (Fast Start Slow Finish/Final): the slope of the front part of the bean temperature curve is steeper (heating up faster), and the slope of the latter part is slower (rising slowly).

SSFF (Slow Start Fast Finish/Final): the slope of the front part of the bean temperature curve is gentle (the temperature rises slowly), and the slope of the back part is steeper (faster).

Standard/Normal: compared with FSSF/SSFF, the slope of bean temperature curve is in the middle, and the temperature is neither very fast nor very slow.

If it violates the premise of the same total baking time and baking degree mentioned above, the baking rhythm such as FSFF/SSSF invented by arrangement and combination is easy to be confused because it does not have the same basis of comparison with the foregoing, so it has not been discussed in the literature.