THE PROCESS IN MOTION

What becomes of the coffee after the drop?

Start the scene or choose a stage. The animation simplifies the mechanism; what follows gives the details and the available references.

▶ Play the process01Cool in five minutes02The gas stays trapped03The valve lets the CO2 out04Two weeks later05The oil rises

Cool in five minutes

The bean leaving the drum is still hot at the core, and the reactions continue. According to Morten Münchow, it must fall below 30 °C in less than five minutes, otherwise it takes on a baked taste and loses acidity; he advises checking with an infrared thermometer. This is a practitioner's rule, with no published measurement to back it.

Read the stages without animation

1. Cool in five minutesThe bean leaving the drum is still hot at the core, and the reactions continue. According to Morten Münchow, it must fall below 30 °C in less than five minutes, otherwise it takes on a baked taste and loses acidity; he advises checking with an infrared thermometer. This is a practitioner's rule, with no published measurement to back it.
2. The gas stays trappedThe CO2 formed during roasting stays largely trapped under pressure in the bean. Its quantity and its pressure depend on the profile: fast, dark roasts produce more and release it faster. Tasting protocols call for at least 8 hours of rest.
3. The valve lets the CO2 outThe bag carries a one-way valve: gas goes out, air does not come in. The CO2 does not react with the bean; as it leaves, it drives the oxygen out of the bag and protects the coffee.
4. Two weeks laterThe CO2 escapes much faster than the aromas: after two weeks, it is almost gone while three of the four aroma markers followed remain near 50% of their value, methanethiol being the slowest. Hence the window of 7 to 21 days often advised for espresso, where the gas hinders extraction under pressure and makes the crema.
5. The oil risesThe oils migrate to the surface by capillarity, in days or months, faster in dark roasts and on decafs; microscopic droplets appear as early as the next day. At the surface, they oxidize and go rancid. Five enemies: time, heat, moisture, oxygen and UV light.

To remember: CO2 leaves far faster than the aromas: this gap opens a resting window, which oxygen and oxidized oil then close.

In history: As early as the 17th and 18th centuries, coffee was sprinkled with water after roasting; fraud on weight was grafted onto this practice later.

Read the full article and its sources ↓

The CO2 formed stays largely trapped under pressure in the bean; quantity and pressure depend on the profile, and fast, dark roasts produce more and release it faster. Smrke et al. (ZHAW, 2018) measured by time-resolved gravimetry that CO2 escapes much faster than the aromas (methanethiol being the slowest): after two weeks, three of the four aroma markers remain near 50% of their initial value when the CO2 is almost gone, which explains the window of 7 to 21 days after roasting often advised for espresso, where the gas hinders extraction under pressure and makes the crema.

The CO2 does not react with the bean; it drives the oxygen out of the bag with its one-way valve and protects. The oils migrate to the surface by capillarity in days or months, faster in dark roasts and on decafs, and oxidize there into rancidity; microscopic droplets appear as early as the next day. Five enemies: time, heat, moisture, oxygen, UV light.

Tasting protocols call for at least 8 hours of rest (professional training), and color measurement between 30 minutes and 4 hours (SCAA 2015); Roast magazine notes that the ideal resting time depends on how the green was processed (“The waiting is the hardest part”).

Gagné 2021, § 8.1-8.4, pp. 159-161, after Smrke et al., J. Agric. Food Chem., 2018, and Schenker et al. 2000; Clive Coffee, Is your coffee too fresh? (accessed 09/07/2026); professional training document, tasting guide, p. 3; SCAA Standard 2015; The Book of Roast vol. 2, table of contents

Cooling fast, and a disagreement over the status of the quench

The plate describes the tray, the fan and the stirring arm, and gives no threshold. Münchow gives one, with the taste consequence that justifies it, and in passing he opens a disagreement over the one technique that allows going faster.

Under thirty degrees in less than five minutes

The coffee must fall below 30 °C in less than five minutes after the drop, otherwise it will taste baked and lose acidity. The reason is the one that governs this whole plate: a bean leaving the drum is still hot at the core, the reactions continue there, and the end of the roast is not the drop but the moment when the temperature falls low enough for nothing to move forward. Five minutes of slow cooling is a profile extension that no one has plotted and that the recorded curve does not show.

Münchow recommends the infrared thermometer for checking, for two reasons worth separating: precision, and hygiene, since an instrument that measures from a distance does not touch the coffee. It must also be said what this threshold is not: in his book it is backed by no measurement and no reference. It is a practitioner's rule, consistent with the rest and unverifiable as it stands.

The quench: condemned in itself, or perverted by use

The plate ranks the water quench among the bad practices, recalling that as early as 1922 the sprinkling meant to recover three to four percent of weight was disapproved of by the best roasters. Münchow holds a noticeably different position, and it must be given in full because it does not rest on the same facts.

In theory, he writes, the quench is harmless if the quantity of water is controlled: the water vaporizes on contact with the scorching bean and leaves with the airflow, without leaving the bean any wetter than it was. The problem is one of use. Industry applies a ratio that leaves the bean at 5 percent moisture, against 1 to 1.5 in specialty, and sells at the price of coffee the water it has added. He adds that he has seen the quench used with extreme care on high-quality beans, without noticeable degradation.

The difference with the plate is therefore not about the facts, it is about the status of the practice: condemned in itself in one, perverted in the other. And Münchow proposes the one test that allows deciding case by case, which is more useful than a position of principle: measure the moisture of the roasted bean. A coffee quenched honestly sits where the others sit; a coffee quenched for weight gives itself away at the first moisture analyzer. This plate therefore does not have to choose between the two judgments, it can give the criterion.

The Book of Roast complicates the picture further, and instructively: sprinkling after roasting was common in the seventeenth and eighteenth centuries, long before anyone imagined using it to cheat on weight. The fraud grafted itself onto a gesture that preceded it by two centuries, which partly explains its persistence: it never had to be invented, only abused.

Morten Münchow, Roasting Foundation, CoffeeMind, p. 18 for the cooling threshold, the infrared thermometer, the quench and the moisture left by industrial use, p. 19 for the measurement of the roasted bean's moisture as a test; The Book of Roast, Roast Magazine, JC Publishing, 2017, pp. 27 and 28, for sprinkling after roasting in the seventeenth and eighteenth centuries; Ukers, All About Coffee, 1922, for the disapproval of sprinkling meant to recover weight.