Do You Wash Green Coffee Beans Before Roasting?

Washing green coffee beans before tossing them into the roaster may sound strange to you, but some people do it. When I first began roasting, I looked into this method to find out the benefits and drawbacks.

In general, washing green coffee beans before roasting will result in uneven roasting to either the core or the outer part. Due to the unevenness of roasting, the coffee flavor is affected in a negative way.

To find out more about why coffee enthusiasts don’t recommend washing coffee beans before roasting, keep reading.

What Does Washing Do To Green Coffee Beans?

Coffee beans are hygroscopic — which means they easily absorb and hold moisture. If you put the green coffee beans in water, they will absorb a huge amount of moisture. You will need to dry them again before you roast them.

Green coffees bought at grocery stores contain 10 percent to 12 percent of moisture — the accepted moisture content of the International Coffee Organization prior to roasting. Washing them will increase the moisture level of the beans. 

If your green coffee beans are wet before roasting, you will get a bad result. The beans will go hotter before they caramelize. As a result, you’ll get a burnt coffee bean outside and raw inside, or the other way around. The taste gets badly affected, too, as it gives a grassy-like flavor.

Why Do Some People Wash Coffee Beans Before Roasting

People wash their coffee beans to remove the chaff. This part doesn’t make a massive effect as roasting removes the chaff. Before dried and packed, coffee beans are already washed, so there’s no need to repeat the same process.

Moisture is another reason why people wash the coffee beans before roasting. If you’re going to do the pan-stove roasting, wetting the beans may work. In pan-roasting, beans roast through conduction, which means the beans absorb heat from the metal. Technically, the outside of the beans absorb the heat first. The roasting starts from the outside to the inside.

On the other hand, coffee air roasters use convection. Convection means the hot air roasts the coffee beans. In convection, the heat penetrates the core of the beans. This shows that the roasting starts from the inside to the outside of the bean. If you put wet beans in, the core can get burned before the heat roasts the outside of the coffee beans.

Can You Wash Coffee Beans?

All beans get washed after extraction from the fruit. This stage removes the remaining residues of the fruit that stick on the beans. 

Washing beans prior to roasting renders no benefit, nor does there exist any research telling the necessity of it. Technically, you’ll end up repeating the initial process that the coffee beans underwent before they get packed and sold to market.

Unless on special occasions like the coffee beans spilled onto a dirty surface, make sure you dry them. Moisture has negative effects on coffee beans in the long run. Storing wet beans allows for the development of bacteria and molds that can cause serious ailments.

Molds develop harmful compounds on coffee beans known as mycotoxins that can cause hypertension, cancer, kidney disease and brain damage. As much as you can, do not wash coffee beans before storing them.

Why You Shouldn’t Wash the Coffee Beans Before Roasting

Coffee beans absorb and store moisture fast. Roasting wet coffee beans give unevenly roasted beans. If you’re doing the pan-roasting, moisture allows the outer part of the beans to cook faster than its core through conduction. However, if you’re using a hot air coffee roaster, the inner part of the coffee beans roast more quickly than the outer part. You will end up having a grassy-tasting coffee as some parts roast unevenly. 

In cases where you washed the coffee beans and dried them again before roasting, this may work. However, the coffee would taste different. It loses its natural flavor. The resulting coffee is a clean tasting coffee, but many coffee enthusiasts complained that washing coffee beans will take away the natural taste, making it dull.

How to Prepare Coffee Beans for Roasting

Green coffee beans bought from stores are ready for roasting, but if you’re growing your coffee plants or have coffee berries at home, you can prepare the coffee beans for roasting using the following steps below.


Coffee plants bear fruits called coffee cherries. You can pick up the coffee cherry when they turn ripe with a deep bright red color. 


You can remove coffee beans from the cherry fruits known as depulping. Depulping comes in different ways such as:

  • Crushing and grinding the cherry fruit to separate the seeds or most commonly known as the coffee beans
  • Soaking the coffee cherries overnight so that the pulp loosens up from the coffee beans
  • Using your hand to squeeze the coffee beans out of the fruit 

Industrialized coffee processors use machines called depulpers to separate the coffee beans from the fruit.


Once coffee beans get extracted from the fruits, they undergo rinsing or washing. This method washes off the fruit residues and the remaining pulp away from the beans. 


To remove the slippery texture, soak the beans for 24 hours or until you can no longer feel the slimy texture on the coffee beans. You can skip this process and directly dry the beans if you prefer a more natural and fruity-tasting coffee.


Green coffee beans should contain 10 percent moisture before roasting. Drying also plays a crucial role in the storage life of coffee beans. Coffee beans that contain a high amount of moisture allow for mold and bacteria formation, which makes coffee dangerous to consume.

How to measure coffee beans’ moisture content?

To have the best cup of coffee, investing in a coffee moisture meter makes a good choice. A coffee moisture meter measures the amount of moisture present in coffee beans.

Monitoring the moisture is a big deal for coffee producers and roasters. The International Coffee Organization sets a standard of 10 to 12 percent moisture in coffee beans as a good moisture level because the moisture content impacts the quality of coffee beans upon roasting and tasting.


To wrap it up, washing green coffee beans before roasting leads to bad quality coffee. Washing allows moisture absorption into the beans that makes them unevenly roasted. Too much moisture downgrades the quality of coffee.

Washing coffee beans to remove the chaff will give no benefits. Chaff comes off the coffee beans while roasting. Washing before roasting may work on pan-roasting as the roasting begins from the outer part before the core.

Washing coffee beans will affect the flavor of the coffee in two ways. First, the unevenly roasted beans give a grassy flavor which makes drinking coffee unpleasant. Second, washing coffee beans and drying them for the second time washes off the natural fruity flavor that makes a cup of coffee distinct.

Preparing coffee beans before roasting comes in four steps. The initial stage involves harvesting the ripe coffee fruits. Next, coffee beans get extracted from the coffee fruits. After bean extraction follows rinsing to remove the fruity residues. You can either soak the beans or dry them directly right away after rinsing. Once the coffee beans get 10 to 12 percent moisture, you can toss them in the pan or coffee roaster.

Remember that moisture plays a huge part in making the best coffee. Make sure that you avoid doing things that can increase the moisture level of the coffee beans — that includes washing the coffee beans before roasting.

Tim S.

Tim loves roasting, brewing, and experimenting with coffee. After years of perfecting this craft, working as a barista, and owning a small coffee service in college, he has decided to share his knowledge with the world.

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