# Sour Tasting Roast - Why?



## JHCCoffee (Jan 20, 2018)

Folks

I have a limited number of roasts under my belt, with my Behmor 1600 Plus. I completed a roast Saturday PM and made a cappuccinio this Sunday AM. I encountered sour notes. I am trying to determine whether this was due to: a) the coffee being too fresh (needs to rest 3 days?), or my roasting profile, or the end roast, or my barista technique (doubtful).

FYI, I have fairly good espresso technique and consistancy (been pulling regularly quite tasty shots, using roasted coffees acquired from a local coffee roaster), so I am confident that the sour notes are not due to my barista skills (although I do know barista techniques to correct for sour notes, which I have not yet employed). FYI, the shots ran within a reasonable time and looked good through my bottomless PTF.

The Roast was ended as either a Full City + or Vienna, based upon been colour and appearance (using the SweetMarias roasted bean photo chart). I used Brazil Bourbon Santos (50%, Samatra Mandheling (25%) and Guatemala Antigua (25%), blended prior to roasting. Total of 110g coffee. The roast profile ended up something like this, using a thermocouple probe placed close to the drum:

1 lb buttom setting on P5, to set to manual, all to allow full time flexibility.

On P5

- 3 min elapsed - 210 F

- 5 min elapsed - 280 F

- 5:49 elapsed - 300 F

- 8:49 346 F - possible FC (I am hard of hearing)

So went to P4 for Roast Development

- 10:30 still hovering at 348F

So went to P5

- 10:48 to 13:14 peaking at 385F

- SC at 13:14

- Hit "Cool" - 2 minutes in Behmoor with door closed

- then stopped and transfered to collander with airblower (clean shop vac in reverse), for rapid cool down.

Roast had sour notes. Just didn't like the flavour.

FYI, had this same coffee blend from the same coffee roasting company, with the Brazil ordered as "medium roast", the Sumatra ordered as "dark" and the Guatemala ordered as "dark". So 50% medium and 50% dark. And liked the taste. Nice complexity. Nice sweetness. No sour notes.

Also FYI, the blends I have been ordering have tended to be darker. Likely Vienna to French in these blends. Yet I have had "medium" roast blends from another local roaster and quite liked those.

Please comment on the roast profile. And the reasons for the "sourness".

Thanks for your help.

JCafe


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## Rob1 (Apr 9, 2015)

Possibly poor development. Split a bean in two with a sharp knife or razor and see if it's the same colour throughout. It looks like you decided to increase your temperature after first crack? I'm not sure how the Behmor works but I can't imagine this is wise. Also, what batch size is the roaster designed to take? You mention a 1lb button setting, yet you're roasting nothing close to that. You might not get anything good without increasing your batch size to whatever is appropriate for the roaster.


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## Batian (Oct 23, 2017)

It is not generally considered good practise to blend prior to roasting, (but is not to be always ruled out). The differences between each type of bean etc can not be catered for. You are comparing a coffee that was blended post roast with one that was blended before roasting.

As you are familiar with Sweet Marias, refer to their article for more detail about pre and post roast blending:https://legacy.sweetmarias.com/library/blending/

Placing the thermocouple probe close to the drum may have little relevance as to what is going on inside the bean mass. Does your roaster show temperatures inside the drum and preferably in the bean mass?

Rob1's comment regarding development and weights are likely to be the main reasons for failure, but give the roast 7 days and try it again.

Have fun!


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## Hasi (Dec 27, 2017)

+ roast defects are best determined by a cupping routine.

Never judge a milk drink - too many flavours are being altered or covered. And imagine your milk was on the brink of getting sour?

SCAA protocol (http://scaa.org/PDF/PR%20-%20CUPPING%20PROTOCOLS%20V.21NOV2009A.pdf) suggests to *cup* between 8 and 24 hours post roast.

For proper development as an *espresso-ready* bean allow for more than three days of rest. Depending on beans, degree of roast and religious views this can be up to 10 or more days... there's at least as many opinions on that bit than there's beans in your drum.









Given your 8:49 346F - 10:30 348F you most likely stalled the roast.

Heat timing around First Crack is the most crucial point in roasting: https://www.scottrao.com/blog/2018/2/24/what-is-baked-coffee-most-pros-dont-know

Experiment with your controls so your temp is constantly rising through first crack but be aware you may encounter a temp drop (as explained in above link) followed by a boost (too much heat input), depending on probe sensitivity. Scott Rao's article led me to utilise thinner probe sheaths so I could spot the problem and adjust my technique.

Happy roasting!


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## Tsangpa (Nov 26, 2017)

My guess is that the sour notes are coming from some under developed beans. This may reduce a little with more resting, but probably won't disappear completely.

It could be due to the mix of beans. Guatemala beans seem to be grown at higher altitudes than Brazilian or the Sumatran beans so they need a different roast profile as they'll be denser and take more time to fully develop.

If 75% of the roast is lower density beans then you'll hear first crack when they're ready but the Guatemala beans won't be at that level of roast. Externally they may look evenly roasted but they won't be.

Try the same roast again but with a 50/50 mix of the Brazilian and Sumatran and see if the sourness if gone. Or better still roast each variety of bean on its own and then blend afterwards.


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## JHCCoffee (Jan 20, 2018)

Tsangpa said:


> My guess is that the sour notes are coming from some under developed beans. This may reduce a little with more resting, but probably won't disappear completely.
> 
> It could be due to the mix of beans. Guatemala beans seem to be grown at higher altitudes than Brazilian or the Sumatran beans so they need a different roast profile as they'll be denser and take more time to fully develop.
> 
> ...


Thanks for your fulsome advise, Tsanga. Will be re-tasting that coffee, and roasting some fresh coffee, this weekend.


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## JHCCoffee (Jan 20, 2018)

Thanks All for your excellent advise. Will be re-tasting that coffee, and roasting some fresh coffee, this weekend.


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