[breathable] Coffee beans: growing beans is not as easy as you think.

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The fresh coffee is better. Right? This statement is actually not entirely true.

Although no one wants to drink out-of-date old beans, the roasted coffee beans will be boiled directly, and their flavor will certainly disappoint you, because the coffee is still in a state of massive exhaust.

Whether you are a roaster or brewer, you must understand exhaust. This article tells us what exhaust is, how it affects the coffee you make, and how to do it.

What is exhaust?

Exhaust is the process of emitting gas from coffee beans after roasting. When you bake coffee, a large amount of carbon dioxide and gas are produced inside the beans.

Many gases are released in the first few days after baking, but the problem is that these gases release small bubbles when you brew, affecting your coffee, which can damage the contact between coffee powder and water, resulting in uneven extraction of flavor and aroma substances.

In other words, if you brew freshly roasted coffee, these gases will have a negative effect on the flavor of your coffee.

For this reason, it is better to wait a few days before making coffee after baking. The period of carbon dioxide emissions and chemical changes is called exhaust.

Why does coffee have carbon dioxide?

When the coffee is roasted between the first explosion and the second explosion, the beans will degrade, and at about 220 °C, the sugar will break down into several different compounds, including carbon dioxide. The coffee beans begin to turn brown because the water loss is also reduced.

Ensei Neto, founder of The Coffee Traveler, told the author that degradation is the most important chemical reaction at the end of baking, because when degradation is converted into sugar. When the energy is released, the gas is produced.

Exhaust makes the coffee just right.

But the carbon dioxide in coffee beans is not a bad thing, it plays an important role in the quality of coffee. The 2018 Journal of Agricultural and Food Chemistry mentioned: "carbon dioxide is an important indicator of coffee freshness and plays an important role in shelf life and packaging, affecting the process of coffee extraction, affecting the formation of crema in espresso, and may also affect the sensory flavor characteristics of coffee. "

When the coffee beans exhaust too much, the flavor will be less distinct. The secret is that the exhaust time should be moderate, instead of waiting for the beans to grow old for too long. Juan Mario Carvajal, founder of the South American Fine Coffee Association, said: "the gas that is still released is an indicator of the freshness of coffee beans, but when the coffee is too fresh, it will prevent the coffee powder from being fully extracted. "

If you use coffee beans that are not exhaust long enough, it may take a long time to extract a dose of espresso because the gas can hinder the flow of water. These gases help to form crema because bubbles are produced during extraction, but the flavor is also less ideal because the gas also interrupts the extraction process.

Joe Behm is president of Behmor, a company that makes boutique coffee association-certified household bean dryers and smart brewers. He says the exhaust of the coffee is important because it makes the coffee taste brighter.

He gave an example of his award-winning Behmor 1600 Plus for roasting Guatemalan coffee. After 72 hours of roasting, the coffee has a rubber flavor, but after 96 hours, the chocolate flavor of the coffee becomes obvious, and the flavor framework of the coffee is more complete.

How long does it take to exhaust?

Exhaust will disperse the carbon dioxide produced by the coffee during the roasting process, but we don't want the gas to disappear completely, but the coffee has just the right amount of gas when we want to drink it, and the right amount of carbon dioxide will make the coffee less insipid.

However, how long to put after roasting depends on many factors. Coffee beans are usually suitable for brewing three days to two weeks or three weeks after roasting, but the difference of each kind of coffee will also make the exhaust time different. brewing method, treatment method, baking degree will affect the exhaust time.

Sharayah Harper, co-founder of Uncharted Coffee Co in the United States, said: "Coffee fruit harvest and washing procedures will always be different, drying procedures will be different, water quality will be different, so I think this is why the exhaust time is also different." Coffee beans are also large and small, so the content of water and gas in them will be different. "

The method of brewing and cooking determines how long the bean culture period is.

If the coffee beans are used for hand flushing or pressure pots, they can be used as soon as possible a few days after baking, because the coffee has a long contact with water, so you don't need to exhaust too much.

On the contrary, when we want to make espresso, because the brewing time is very short (usually only more than 20 seconds), the bubble will affect the extraction result to a greater extent.

Joe said: "espresso is very special, it takes longer to grow beans, you won't see anyone take freshly roasted coffee directly to extract and concentrate, the key is to raise beans and exhaust, so that the coffee can play its flavor when brewed. "

Mark Michaelson, chief baker at Onyx Coffee Lab and champion of American bean baking in 2017, said: "if the beans are extracted and concentrated, we usually want the coffee to be used five to seven days after roasting, which makes it easier to extract the coffee and takes less time to brew the beans by hand. ) "

He also said that when Onyx Coffee prepares beans for competition, it is usually kept for 10-21 days before use, because it makes it easier to extract coffee. If you can wait at least three to five days after baking before using coffee beans, it can help prevent inconsistent coffee extraction.

Coffee treatment affects the period of soybean cultivation

The three main treatments of coffee: washing, tanning and honey treatment can also affect coffee exhaust, Mark said. "We think sun-cured coffee beans need a longer exhaust period than water washing. "

"if the sun beans are cooked for three to five days after baking, there is often a problem of being too fresh. It takes more time to exhaust the sun-dried beans. "

The degree of baking affects the exhaust time

Deep-roasted coffee accelerates the exhaust of coffee beans because they are highly degraded. Sugars are converted more heavily, and there are more small cracks that cause more carbon dioxide to be released.

Sharayah said: "shallow roasted coffee beans are closer to the unbaked state, which means that the lighter roasted coffee beans need more time to exhaust. "

Ensei also reminded me that if coffee beans are roasted unevenly, it may lead to uneven development of coffee beans; different degradation time will affect the development of coffee beans, and then affect the exhaust rate of cooked beans.

How to maintain the freshness of coffee beans

How to make sure that your coffee has been raised properly when you drink it?

Sharayah suggests building a good organizational system so that your coffee beans won't last long. "keeping an accurate record of the baking date is very helpful, especially when there is a large amount of baked beans. "

Mark said that Onyx will use nitrogen to fill coffee bags, with nitrogen, coffee beans can last longer shelf life.

It usually bags the coffee 20 minutes to an hour after baking, but only if the coffee bean bag has an exhaust valve. When customers get our coffee, it is usually three days after baking, the exhaust valve is to let the coffee beans exhaust normally during transportation, if there is a collision, it can prevent the bean bag from bursting.

The secret of self-baked exhaust and bean cultivation

Some bakers may not have nitrogen-filled equipment, but they will not have the problem of massive baking or long-distance transportation.

Joe explained: "if the coffee starts to lose its flavor within seven days after roasting, then you will lose something in the coffee on the eighth day. As soon as I open the raw bean storage tank, I will bake it as soon as possible and leave it for four days. I just use a natural cycle so that the coffee doesn't bake too much at one time, so I can drink the best coffee. "

He also uses large yogurt cans to store roasted coffee beans, which he says can be vented because they are not sealed. If you put it inside, it will not be affected by the sun, because the white plastic material outside is opaque. This is an ideal storage container for Joe. Due to the different humidity and climatic conditions in different countries, Taiwan's environment is relatively wet, so it is recommended to store coffee beans according to the store's preservation method.

There are also many people who encourage the use of sealed cans to store roasted coffee beans to maintain the freshness of coffee. But to remind you, if you are baking at home, you must store a container that emits carbon dioxide from coffee beans, and you must consider how much coffee beans are roasted and whether they can be used up in a fresh state.

Successful venting will give you a wonderful taste or a disappointing cup of coffee, but it's not complicated, just pay attention to the baking date and let the coffee beans emit the right amount of carbon dioxide.

So remember when the coffee beans are baked, taking into account the storage space and cooking methods will also affect exhaust. The exhaust time required for each type of coffee beans is also different, and some will take a longer time to exhaust. If the coffee doesn't taste as good as you expected, try to exhaust it for a few more days, just be careful not to turn it into an expired bean.

Translated from Perfect Daily Grind

Translated by Cheng Zhen Coffee