Roaster coffee bean size and color distribution

Hello everybody… i am new to the forum and i searched for this topic and did not find anything related…

I am trying to see if I can gauge the quality of the roasted coffee by looking at it… meaning, can I tell the quality control of the roasting process if i start finding beans of different sizes and different colors? Or is this normal in coffee? I understand coffee beans are seeds and therefore the variation should be expected, but how much is really expected and how much should the roaster handle in order to limit this variation on the coffee… Again, I am new and I am trying to figure out if this even matters.

Thanks for any feedback…

Hey there

Regarding beans of different sizes; that all depends on the variety. i.e. did you buy a bag of 100% red bourbon, or did you get a bag that’s a mix of different varietals, as that would have the biggest effect on bean size.

Colour is probably the easiest one to go for i think; if there are beans that are obvious shades lighter in the bag, they’re called quakers and they come from coffee cherries being picked too early at origin so they aren’t ripe enough, and because of that they don’t roast in the same way as the beans from ripe cherries would.

this page here has a really good explanation on what can cause a certain amount of your beans to look abnormal/different to how the others do.

But yes, you can to an extent gauge the quality of beans by looking at them, although the best way to test the quality is to brew and taste!:slight_smile:

hope this helps,


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To some extent the quality of a given lot of coffee can be determined by just looking at it… are the beans close in size, or is there a wide range of sizes in the bag? Sometimes the single variety is screened so the beans are all within a certain range of sizes, other times they are not. This alone is not a reliable determinant of flavour. I’ve had some unscreened coffees that roasted up very evenly and had amazing flavour. Other times, not so much.
As to colour… after roasting… one of two things has happened: either, as the other Nico explained, less than careful picking includes too many unripes. This IS a quality determinant, as the hard quakers taste sour or otherwise “off”. Lower quality coffee can often include many unripes. The other possible explaination for colour variation is improper modulation of heat application during the roast. Gentler heat allos the beans to draw heat from the roaster more evenly, too rapid heat application can scorch some and leave others not heated enough throughout the roast. Learning to modulate heat application to keep Rate of Rise under control during the various parts of the roast is key to a good roast.

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Hey @carspidey,

When you say the ‘quality of roasted coffee’, there’s 2 things that come to mind. First, the quality of the green. For this, if the roaster is buying high-quality screened coffee, then the bean/seed size should be reasonably uniform and we’ll assume for this forum that it has little defects and we’re not talking about a blend. The second thing (and the one I think you’re getting at here), is if you can tell the quality of roast from visual cues. Similar to the comments from #the2nicos below, taste is king, but there are a couple of indicators that lend to the expectation of a decent roast. 1. Are the beans a relatively even colour and ‘plump’ or full without much wrinkling? and 2. How do they smell? Are they fragrant and pleasant or are they a little grassy still?

From my personal experience, there’s a couple of other things I like to check if I can. The first is the colour of the inner chaff still clinging to the ‘seam’ of the bean. If it’s light brown or darker and the seam is slightly open, then I think this is a good thing. If the chaff is still a little greyish-looking and the seam is tightly closed, then it’s in my head already that there’s likely some underdevelopment. Sidebar: this is much more common and to the point of being almost a problem among ‘specialty’ roasters. The other thing I check is how brittle the beans are; can they easily be broken with my fingers? If so, then this too s a good sign. If I have to dig my thumb nails in to rip them apart, then I assume (either rightly or wrongly) that the batch is again underdeveloped. There’s obviously exceptions here, but these are the cues I like to use.


…it should be noted however that different processing methods can also have a dramatic impact on the visual ‘look’ of a roast. Natural processed coffees tend to be a little more mottled in appearance, especially African coffees. On the opposite side, washed Centrals and South American coffees usually roast very evenly.