[Homeroast] Sour coffee taste

Tom & Maria - Sweet Maria's Coffee sweetmarias at sweetmarias.com
Mon Mar 28 18:21:00 CDT 2011

Hi Scot - nice clear macro pictures! I am having some trouble because 
the color is really on the yellow side. I see that there are lighter 
areas on the edges of the coffee, especially the sharp edge on the 
flat beans. If those are whitish it might be age. The coffee looks 
nice, looks dense, nice preparation. But there is one thing: I see 
about 4-5 possible under-ripes. These are smallish, with silverskin 
(chaff) clinging completely to the rounder side and the flat side 
(silverskin itself is totally normal - good in fact). But these 
smaller ones covered in silverskin might be unripe green cherry - you 
really know when you roast to a lighter City roast, and find that 
these come out tan, a quaker bean. That would give sour and baked 
taste. Might be the issue, might not. DP coffees are the ones with 
quakers, but a washed Mexican can often have more than their fair 
share. The "back of your toungue" sourness sounds like astringency to 
me, which would be consistent with under-ripes.

PS - you can upload pics to the forum if you want to post the note 
along with the picture


Hi tom,

Thanks for reply.  I have been roasting 225g batches.  I checked the 
ground vs crushed vs whole color and they look very similar.  The 
beans were purchased in December of last year so it should be last 
year's crop.  Would a "baggy" flavor leave the sour taste on the back 
of the tongue?  I haven't tried any of the coffees from Sweet Maria's 
yet in the Quest.  I'll try a batch tonight.  Pics are attached. 
Please let me know what you think.


>  Date: Sun, 27 Mar 2011 17:38:34 -0700
>  To: homeroast at lists.sweetmariascoffee.com
>  From: sweetmarias at sweetmarias.com
>  Subject: Re: [Homeroast] Sour coffee taste
>  How big was the batch? I don't think that is fast enough to give any
>  off flavors. Many of my sample roasts are in the same range, but they
>  are 100 gram batches too. Yours might be larger. Compare the whole
>  bean surface color to a ground sample, side buy side. If the surface
>  looks a lot darker than the interior then you might have
>  under-developed interior. But I have another suspicion: the coffee is
>  baggy. The reason is that Chiapas new crop would just barely be
>  shipping right now, and that would be lower grown coffees. If its
>  last years, was kept in jute, it's going to have little moisture
>  content, roast weird, and probably have baggy taste too. Hard to say
>  without seeing the green coffee. I could probably tell from a decent
>  macro image of 20-30 green beans
>  tom
>  >Hi all,
>  >
>  >I'd like to ask for some help/advice regarding a recent roast. I
>  >picked up some green Mexican Chiapas from a local roaster and used
>  >it to christen my Quest (after a few batches of Tom's Thumbs Down.)
>  >I took the beans to FC - 8 min to 1st, 11 to finish. The flavor is
>  >OK, but there is a sour taste on the finish. Not the standard
>  >acidic bite on the front of the tongue, but rather in the back. Is
>  >this simply a question of bean quality or can this sourness be
>  >caused by something in the roasting technique. I brewed with both
>  >French press and manual drip with the same results so I don't
>  >believe the brewing method is the culprit. Any ideas?
>  >
>  >Scot
>  >
>  >p.s. Great listserv. This group has really helped me improve my roasting.
>  >
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>  --
>  -Tom
>  ___________________________________________________________________________
>  Sweet Maria's Coffee - Oakland, California - http://www.sweetmarias.com
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Sweet Maria's Coffee  -  Oakland, California  -  http://www.sweetmarias.com

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