Is it a roast issue or a green issue? (Prospective new roasters; you should read this too!)

#1: Post by **luca** » July 28th, 2022, 5:16 am

I separately made the point that if you are a new roaster, you could waste a lot of time if you can't tell if undesired flavours are a roast issue or a green coffee issue and that there are various difficulties in buying green coffee that meets your expectations see here.

Green coffee vendors for home roasters of course probably won't try to intentionally deceive you, but you can expect that they will put their best foot forward without lying, which might mean:
1. they will make some vague, general statements about quality in general;
2. they will describe the good aspects of particular green coffee they are selling;
3. they will stay silent about the bad aspects of particular green coffee that they sell; and
4. they won't update the description as the coffee might get worse with age.

This means that taking vendors at their word in their descriptions of the green coffee that you have got might be optimistic. But if your coffee doesn't taste as you expect it to because of a green coffee issue, you might waste a lot of time and roasts trying to roast it differently to fix the unfixable. So it is pretty important to be able to form an idea of whether you are looking at a green or a roast issue.

The least offensive and most useful way to explore this issue is probably for us to share thoughts on actual examples of coffee, to try to diagnose if there is a roast or a green issue. So post up examples of what you've roasted and how it fell short of your expectations and we can discuss. It would be useful if you provided as much detail as possible.

Before we dive into it, let me make one observation at the outset: I don't care what your preferences are; I care that you are informed and well placed to get the results that you want, and that they are realistic. And I also care that you aren't misleading others to spend their money on something that isn't going to realistically get them the results that they want. But if you like dark roasts, light roasts, robusta, monsooned malabar, yirgacheffee, kenya, brazil, mould, phenolics, whatever; I don't care; I respect your taste preferences and I'm not here to change your mind. Equally, whilst I'm familiar with SCA and COE score sheets, I'm trying not to make this about scores, and I'm not suggesting that you need to be chasing scores. This is about setting and achieving your expectations, whatever they may be.

July 28th, 2022, 5:39 am

So let's dive into it with this question from PIXIllate:

PIXIllate wrote:Back on the topic of defects and how they relate to actual post roast in the cup flavour I wonder if Luca might be able to tell me what defect (roast or green) might cause a papery/cardboard flavour. It reminds me very much of TCA/corked flavour in wine. This is a coffee (washed Guatemalan/Ethiopian blend) I've had many times and none of the other brewing parameters have changed. Assume an EY% of ~21% so it's not under extracted.

Mkane offered:

mkane wrote:^^^^R0R flatline maybe aka baked

It could be baked, particularly if it has a sort of toast type flavour, is dull in aroma, has muted acidity compared with what you might otherwise expect, and if it has a bit of astringency to it, too.

I think that the clarification that we need is when you say you have had the coffee many times before (presumably without this flavour), are you saying that you have had the same blend from earlier crops/harvests and there hasn't been a problem? Or are you saying that you have had this exact crop/harvest/season/blend/whatever, the green hasn't changed, and you are now getting this papery quality? If it's the latter, then it suggests roast. If it's the former, then we can consider if it's roast or green.

#3: Post by **PIXIllate** » July 28th, 2022, 7:44 am

luca wrote:So let's dive into it with this question from PIXIllate:

It could be baked, particularly if it has a sort of toast type flavour, is dull in aroma, has muted acidity compared with what you might otherwise expect, and if it has a bit of astringency to it, too.

I think that the clarification that we need is when you say you have had the coffee many times before (presumably without this flavour), are you saying that you have had the same blend from earlier crops/harvests and there hasn't been a problem? Or are you saying that you have had this exact crop/harvest/season/blend/whatever, the green hasn't changed, and you are now getting this papery quality? If it's the latter, then it suggests roast. If it's the former, then we can consider if it's roast or green.

Thanks for this Luca. Sorry I wasn't more descriptive, I'll try to expand. This is a coffee that is a regular for me, as in one or two bags a month. Consulting my notes the last bag I had was roasted on June 28th, the bag before that on June 15th and this bag was roasted on July 15th. I can't say with any certainty that neither of the blend components have changed but I would guess they haven't. My Roast vision notes indicate all bags were within 1-2 numbers of each other (~19 or Medium).

There are no toasted flavours, more of a muted hollowness with an overriding papery quality and a mild astringency which leads to a shorter, sharper aftertaste. Again this reminds me a great deal of a corked wine in that the original flavours seem to eroded, muted and subsumed when a bottle is first opened, and then the more the air gets at it all that is left is the damp basement/wet cardboard.

Now I should clarify, this coffee is not undrinkable (although I have had some in the past that were similar to these notes but much worse that I didn't consume) and not all of the expected flavours are missing. More that the hollow, papery, astringent characteristics are present and diminish the good qualities.

#4: Post by **LuckyMark** » July 28th, 2022, 8:41 am

Luca I will take a stab at this. Given Pixellate good description that the roasts were similar and done close timewise, the more muted flavours would initially make me think the bag was older and possibly stale. The greater astringency throws me and makes me believe an issue with the grean bean, though what I don't know.

For those reading at home this is an absolute guess.

#5: Post by **PIXIllate** » July 28th, 2022, 8:54 am

The bag in question was roasted on the 15th of this month and opened yesterday the 27th.

#6: Post by **Brewzologist** » July 28th, 2022, 10:11 am

Interesting topic. Over the years I've learned things I blamed on my roast or the green were at times due to other things, for example:

-- age/storage of my greens after I received them
-- how I stored my roasted coffee, how long I rested it, and how much time had elapsed after resting to when I was drinking it
-- how well controlled my roasting environment itself was (e.g. temp/humidity/airflow).
-- suboptimal grinding/brewing

Carefully controlling items like these would be my first goal before moving into a diagnosing roast vs. green. I'm not suggesting this thread dive into those complexities but do think prospective roasters should be aware they also can have an effect.

#7: Post by **mkane** » July 28th, 2022, 2:54 pm

I'm along for the ride as were always changing things up. Coffees are never the same.

Very interesting thread thanks, Luca. I suppose suppliers' names are not mentioned.

#8: Post by **Mbb** » July 28th, 2022, 8:07 pm

I like to order only 1 lb until I've roasted it and like it, and then I'll order larger quantities.

And yeah, sometimes a green coffee will have some undesirable taste. Sometimes it's bitter. One time I got a coffee so bitter when roasted it left a horrible bitter taste all on my cup. The cup had to be scrubbed to get rid of it. Even the same coffee from same estates may not be the same quality year to year. Even some highly touted coffees can be living on reputations from an awesome picking years ago, and not actually be nearly as good anymore

#9: Post by **addertooth** » July 28th, 2022, 8:12 pm

I have tasted multiple commercial coffees that have a "leather" aftertaste. I thought it was an artifact of bad commercial brewing.

But then I roasted some coffee from Bali (Organic Kintamani Natural) taken to the beginning of second crack. It exhibited the same leathery finish (not overwhelming, but definitely present). What is the underlying cause of the taste of a tanned leather belt? If I were to further describe the leather taste, the components would be sour, astringent and tannic. But it (overall) is spot-on for the taste of leather. The home roasted coffee was aged 3 days before sampling.

July 28th, 2022, 8:39 pm

I'm curious how you know what a tanned leather belt tastes like.... I've heard a lot of things used to describe the taste of coffee but that's a new one in my book:)