What is Coffee Bean Chaff? Does it matter?


The chaff of a coffee bean is the silver skin usually left between the two sides of the coffee bean.

It is what is left of the skin around the raw (un-roasted) bean. Most of it falls off during the roasting process, but the parts at the center of the bean sort of get stuck. So naturally the roasting process produces a lot of chaff, but thats another story.

Since the chaff gets removed during roasting, you tend to find a bit more of it in lighter roasts.

So today I want to talk about whether this chaff has an effect on your cup of brewed coffee.

The good parts that you want to get to are the bean (technically it’s the seed), so ideally you don’t want anything else in your cup.

It is often said that chaff adds some papery-ness to the cup.

I didi some tests and would like to share my personal experience, and offer some advice based on that.

How do you get rid of the chaff?

In order to conduct the experiment, I first needed some coffee with and without the chaff.

How did I get rid of the chaff? Well its actually quite easy. Just grind twice.

For the first time, grind really really coarse. Then blow off the chaff. And for the second grind, grind at your usual setting.

Let me give you a bit more detail.

The first very coarse grind.

The photo isn’t easy to see, but just go as coarse as your grinder will let you.

You should get big chunks of beans like this.

And the white stuff you see on the side of the grind catch is the chaff.

A couple of tips.

First don’t do RDT for this step. RDT is a technique where you spray a little water on your beans before grinding them to reduce static.

By avoiding RDT, the static will help you remove the chaff.

Another tip would be to use an other grinder for the first grind. Maybe you have an old grinder that you usually don’t use, that would be fine.

The reason for this is just to avoid readjusting the grind setting every time.

After the coarse grind, move the grounds in to a shallow dish or something and blow on it.

The chaff is paper thin and light, so you can blow off only the chaff. But don’t blow too hard.

Shake a dish to get the chaff stuck below the surface.

As you may have noticed, this step will make quite a mess.

Maybe you want to do this over the sink, some where you can clean up easily.

After blowing away the chaff, the originally 9g dose reduced by about 0.2g.

Would this tiny amount even make a difference?

This is what the grounds look like after removing the chaff.

All that’s left is to regrind at your desired setting.

As a comparison, the grounds with and without chaff look like this.

The method looks to be pretty effective.

By the way, you don’t necessarily need to grind twice. You could blow off the chaff after a first normal grind.

But by grinding coarse first, you get more of a weight difference between the chaff and the ground coffee. This make it far easier to blow away only the chaff.

Is there any taste difference?

Finally on with the comparison.

I prepared 9g of grounds with and without chaff. (9g before removing the chaff to be exact)

Then I brewed them with the same technique, while trying to keep the conditions the same.

The surprising thing was even before comparing the two cups, I could immediately tell a difference with the no-chaff cup.

The word that came to mind was smooth. It did not have the slight edgy-ness that I was used to.

And sure enough, when I compared the two cups, the cup with-chaff had a dryness to it. It has this unpleasant sourness. It’s not a night and day difference but by comparing it, I would definitely taste the difference.

Of course I did a couple of rounds of blind taste tests. And I could tell the no-chaff cup both times out of the two trials.

This actually was a surprise, and quite an achievement for my untrained sense of taste!

Well I guess that just means that the difference was just that significant.

I do think the difference was significant, but at the same time it is from the same coffee bean. Removing the chaff is not going to drastically change the cup.

And if I might add, I can’t distinctively say which cup is ‘better’.

If you dislike sourness in your coffee, you probably will prefer chaff removed.

But it you like a little punch in your cup, maybe the slight edgy-ness from the chaff is what you need.

I did prefer the cup with chaff removed, but for me it’s not enough to go thought the hassle of removing the chaff everyday.

It might be a good trick for your special cups.

Either way, I would strongly recommend that you try it once! It’s free and easy. You might be surprised how just a fraction of a gram of chaff does to your coffee.