Changes

In general, coffee sugars are made accessible by roasting, but the caramelization process also reduces perceptual sweetness over roast time at a similar degree of roast. Additionally caffeine content lowers over time with off-gassing from longer roasts. Acidity also tends to lessen over time past CitY+ and into Full City/Second Crack, until carbonic acidity eventually raises in the darkest roasts. Roasters aim for a consistent rate of rise over time, just as with making caramel, so that the caramelization process does not stop and start haltingly, which will reduce perceptual sweetness as well and lead to uneven bean development.

In general, coffee sugars are made accessible by roasting, but the caramelization process also reduces perceptual sweetness over roast time at a similar degree of roast. Additionally caffeine content lowers over time with off-gassing from longer roasts. Acidity also tends to lessen over time past CitY+ and into Full City/Second Crack, until carbonic acidity eventually raises in the darkest roasts. Roasters aim for a consistent rate of rise over time, just as with making caramel, so that the caramelization process does not stop and start haltingly, which will reduce perceptual sweetness as well and lead to uneven bean development.

Roasting on the Java Master is determined by two PID separate controlled parameters: hot air temperature and bean temperature. Hot air temperature is set on the left PID controller. It should be adjusted based on the bean weight to be roasted and the desired speed of roast, and is the temperature of the air entering the roast chamber. More beans require more heat to roast at the same speed. Target bean temperature is set on the right PID controller, and corresponds to the temperature of the air exiting the chamber. When this temperature is reached, the machine begins its cool down cycle. Note that this number is a significant underestimate of the actual bean temperature, but it provides an easily measured parameter for when to end the roast. This temperature can also be adjusted while the roast is in progress to prolong or end the roast earlier, but note that the PID controller takes several seconds to recognize the change.

Roasting on the Java Master is determined by two PID separate controlled parameters: hot air temperature and bean temperature. Hot air temperature is set on the left PID controller. It should be adjusted based on the bean weight to be roasted and the desired speed of roast, and is the temperature of the air entering the roast chamber. More beans require more heat to roast at the same speed. Target bean temperature is set on the right PID controller, and corresponds to the temperature of the air exiting the chamber. When this temperature is reached, the machine begins its cool down cycle. Note that this number is a significant underestimate of the actual bean temperature, but it provides an easily measured parameter for when to end the roast. This temperature can also be adjusted while the roast is in progress to prolong or end the roast earlier, but note that the PID controller takes several seconds to recognize the change.