# Temperature effect on flavour?



## the_partisan (Feb 29, 2016)

Was curious if anyone has done tests regarding temperature's effect on flavour? Obviously temperature effects extraction, but it seems to effect more so what is extracted in what proportions. Various roasters seem to recommend different temperatures, with no real reasoning, and I'm curious to understand the mechanics and why you would use one temperature over another. For example, if a roaster recommends 96C but not 99C, what is the reason for this? It doesn't seem to quite play along with the dose/grind size/flow rate/brew ratio which have pretty straightforward and measurable effects on extraction.


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## Mrboots2u (May 10, 2013)

Higher temp > potentially l extract more or quicker > i never really messed around alot with it as i prefer to use grind size and ratio to effect taste.

People used to say that the temp decline on a lever allowed for a softer shot ( it drops about 6-8 c in my experience 0 could be its just extracting a little less of the acidity people dont like in espresso or bitterness on the darker roasted. That's all guess work.

Personally for the home barista i think its more important to get a stable temp and know its the same at the stat of each shot , than dialling taste in by temp . Bit then again I am not American , spend time on HB and people play with temp all over the place when drilling in.

Here is an experiment if you have a temp kettle . Make a v60 with one temp at 96 say and one at 88.... see if the time differs.


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## the_partisan (Feb 29, 2016)

I don't have a temp kettle, just a regular Hario Buono and typically use it straight off the boil, so probably something like 98C when its the grinds? Never really tried with lower temps.


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## Mrboots2u (May 10, 2013)

the_partisan said:


> I don't have a temp kettle, just a regular Hario Buono and typically use it straight off the boil, so probably something like 98C when its the grinds? Never really tried with lower temps.


Same here ( no temp kettle ) . If bothered you could just leave the water for about a minute and pour using the same process .


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## MWJB (Feb 28, 2012)

There's a lot of confusion about brew temps, people muddle slurry temp with kettle temp. If you want to brew at 93c for instance you'll want 97c+ water temp. That 4c drop was also assumed to be for water in a vessel at 97c, then coffee dose added...it'll drop more pouring into a brewer.

In reality for a pourover, if you start with water just clicked off boil the slurry will have dropped to 90c or a little under by the end of brew. If you pour that same boiling water into a cupping bowl with a coffee dose in it, you'll likely never see more than 90c slurry temp.

Boiling water (at pour/brew start) has been recommended for longer than I have been alive. Cooler water requires more contact time to hit a similar measurable extraction (but as you note, can influence flavour separately to EY).


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## the_partisan (Feb 29, 2016)

I have a Thermapen (mostly used for baking) but it's always a bit awkward to measure the slurry temps when also pouring at the same time. Has anyone tried to measure slurry temp during a 13-15g V60/Kalita brew?

Not all roasters recommend boiling water, and I don't quite understand the reasoning. But maybe as long as it's above 90 it doesn't really matter or difference is too little to be of any note?

I won't even mention the Aeropress recipes which use significantly lower temps (75C)


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## MWJB (Feb 28, 2012)

I used a Brannan +/-1c thermometer rigged in a Melitta cone to measure slurry for a few 13.5:225g brews.

Brew water at rolling boil at bloom (30s)

89c dropping to 86c

90c dropping to 88c

89c dropping to 85c

Brew times from 2:35 to 3:20

...then I got bored & gave up as I can't get the water in the kettle any hotter.


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## Mrboots2u (May 10, 2013)

the_partisan said:


> I have a Thermapen (mostly used for baking) but it's always a bit awkward to measure the slurry temps when also pouring at the same time. Has anyone tried to measure slurry temp during a 13-15g V60/Kalita brew?
> 
> Not all roasters recommend boiling water, and I don't quite understand the reasoning. But maybe as long as it's above 90 it doesn't really matter or difference is too little to be of any note?
> 
> I won't even mention the Aeropress recipes which use significantly lower temps (75C)


Aeropress recipes







.

Gotta be unique when compete.

As before temp is a variable to extract same as grind and water to coffee ratio. Personally I wouldn't get too worried about roaster recipes. You don't have their water, grinder or taste buds...


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## the_partisan (Feb 29, 2016)

MWJB said:


> I used a Brannan +/-1c thermometer rigged in a Melitta cone to measure slurry for a few 13.5:225g brews.
> 
> Brew water at rolling boil at bloom (30s)
> 
> ...


Do you reheat the kettle in between pours, and how much water you put in? I typically don't like to put in more than I need to use, around +30g what I need.


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## Zephyp (Mar 1, 2017)

Does water temperature affect parameters that other variables can't? If it's all pretty much a matter of extraction, and you can affect that with temperature, grind, dose and technique, you shouldn't be able to get something out of a bean with 95C that you wouldn't with 99C?


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## MWJB (Feb 28, 2012)

the_partisan said:


> Do you reheat the kettle in between pours, and how much water you put in? I typically don't like to put in more than I need to use, around +30g what I need.


No reheat between pours, unless I'm doing a long bloom (90s & reboil) then all brew straight in.

I fill the Buono electric to just above the spout (looking inside), maybe 50-100g over the 225g brew water?


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## Step21 (Oct 2, 2014)

I find brews on the Brazen automatic machine taste horrible if the pre set temp goes above 95C. The slurry temp here is probably higher as it is sealed.

In manual brewing I find that you will get a different cup if you keep the temperature at a fixed 98C for all pours rather than bloom at say 98C and then let fall. It seems to mainly change the nature of the fruit acidity. I find most roasters notes are hit when blooming at 98c then let fall and rarely hit with a fixed temp.


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## MWJB (Feb 28, 2012)

Zephyp said:


> Does water temperature affect parameters that other variables can't? If it's all pretty much a matter of extraction, and you can affect that with temperature, grind, dose and technique, you shouldn't be able to get something out of a bean with 95C that you wouldn't with 99C?


Extraction at a molecular level is complicated & beyond most of our access. Extraction as an averaged mass of everything is something we can measure, but doesn't fully explain subtleties of taste, especially when making small individual brews (as opposed to brewing beer, say, at commercial level).

+/-2C isn't much of a variation, not sure that would be enough to make a significant difference?

MIT did some experiments with immersions in the late 50's, they found they could hit mid box extraction yields at 60C, but by holding the temp stable (not declining like an Aeropress/cupping/French press) & giving the brews more time. The main component that seemed to reduce proportionally with temp was tannin.


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## Mrboots2u (May 10, 2013)

Zephyp said:


> Does water temperature affect parameters that other variables can't? If it's all pretty much a matter of extraction, and you can affect that with temperature, grind, dose and technique, you shouldn't be able to get something out of a bean with 95C that you wouldn't with 99C?


Depends where you are with other variables.

Perhaps someone can't grind any finer etc....


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## the_partisan (Feb 29, 2016)

I wonder how temperature affects solubility, i.e. how much more soluble are solids at 90C vs 80C.. is the relationship linear?

Is the bad flavours when Brazen is set to 95C due to over extraction or is it due to temperature?

Rao also recommends slurry temp 91-94C for batch brews, and shower head temp of 93-94C.


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## MWJB (Feb 28, 2012)

the_partisan said:


> I wonder how temperature affects solubility, i.e. how much more soluble are solids at 90C vs 80C.. is the relationship linear?.


I think solubilty, in terms of brew efficiency, is more governed by flow/replacement of clean water around the grounds.

I did some Aeropress brews where I steeped 10g in 30-40g of water, for 30s, pressed & repeated up to ~200g water total. The water couldn't have held much heat in those small amounts, no reheating of kettle & it was easy to extract 23-24% in drip mode.


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## Zephyp (Mar 1, 2017)

Mrboots2u said:


> Depends where you are with other variables.
> 
> Perhaps someone can't grind any finer etc....


Yeah, If you got limitations in other ways I can see it used as means to adjust extraction, but most users that struggle with stuff on the forums got a Lido, Feldgrind, Encore or similar. Adjusting temperature is a very common suggestion to someone looking for better results.

I also see many saying they use different temperatures for different coffees.


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## MWJB (Feb 28, 2012)

Zephyp said:


> Yeah, If you got limitations in other ways I can see it used as means to adjust extraction, but most users that struggle with stuff on the forums got a Lido, Feldgrind, Encore or similar. Adjusting temperature is a very common suggestion to someone looking for better results.
> 
> I also see many saying they use different temperatures for different coffees.


Cooler water is always going to extract less, for the same grind & method. Boiling water is as hot as is practical...life just got simpler  I have only seen coffee specific temp recommendations for espresso?

For manual brews you can always lift extraction by drip brewing with more pulses, or steeping longer &/or insulated.

None of those grinders should be presenting issues for the more common brew methods.


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## Mrboots2u (May 10, 2013)

Zephyp said:


> Yeah, If you got limitations in other ways I can see it used as means to adjust extraction, but most users that struggle with stuff on the forums got a Lido, Feldgrind, Encore or similar. Adjusting temperature is a very common suggestion to someone looking for better results.
> 
> I also see many saying they use different temperatures for different coffees.


I was reffering to espresso recipes, sorry didn't make that clear.

IMHO you are just making your life complicated for people saying x coffee has to be at x recipe for brewing.

People have different water chemistry , grinders and mouths . All these things will negate a difference of 2 c in a recipe .

Re Aeropress its worth noting alot of competitions people are asked to use the same coffee , so they find inventive ways of making brewing different with temp and doses etc.


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## Wajid (Apr 24, 2018)

I'm pretty new at experimenting with the French press, but I found that darker roasted beans which are oily brew better at lower temps.

So far, I would say:

- Dose (too low produces a weak cup)

- Time (too long can increase bitterness in oily beans)

- Temperature (lower for oily, around 84oC, higher for light roast, I stick to 94oC max)

- Grind (I don't play with this variable too much, settle at a coarse setting, 500 on the Kinu M47)

I'm currently playing with some Tesco finest Sumatra beans which are dark and oily - so far the best cup has been with 21g in 400mL for 2m30s at 82oC, but it was a bit weak. My next step is to try 24g in 400mL for 2m30s at 82oC.


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## MWJB (Feb 28, 2012)

Wajid said:


> I'm pretty new at experimenting with the French press, but I found that darker roasted beans which are oily brew better at lower temps.
> 
> So far, I would say:
> 
> ...


Even longer time will get you past the bitterness, grinding finer too. It's pretty much impossible to over-extract in a French press.

84c will give a low extraction, which you my well like.

I brew all French presses with water straight off the boil (probably


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## ajohn (Sep 23, 2017)

I found a definite temperature effect on a Sage Barista Express. Initially I did what Sage suggest, flush through the basket that is going to be used, dry it add grinds etc. I often make 3 drinks on the trot and decided to taste each one. I wouldn't say taste changed only the degree of it, last shot was easily the strongest. At that point the whole end of the portafilter was very hot. Cold on the first, warmer on the 2nd. Since then I have taken steps to get the portafilter really hot as some would do on a typical E61 machine with an all metal grouphead. Due to heat transfer the water tamperature as far as the grinds were concerned would be lower than what the machine supplied - for the entire shot time by the look of it unless the portafilter is preheated.

John

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## MWJB (Feb 28, 2012)

ajohn said:


> I found a definite temperature effect on a Sage Barista Express. Initially I did what Sage suggest, flush through the basket that is going to be used, dry it add grinds etc. I often make 3 drinks on the trot and decided to taste each one. I wouldn't say taste changed only the degree of it, last shot was easily the strongest. At that point the whole end of the portafilter was very hot. Cold on the first, warmer on the 2nd. Since then I have taken steps to get the portafilter really hot as some would do on a typical E61 machine with an all metal grouphead. Due to heat transfer the water tamperature as far as the grinds were concerned would be lower than what the machine supplied - for the entire shot time by the look of it unless the portafilter is preheated.
> 
> John
> 
> -


We were discussing brewed coffee with water heated in a kettle. From the moment the kettle clicks off, the water temp is dropping it cannot rise.

For espresso you have heated water continually deliver to a sealed compartment, depending on the machine the puck will rise then fall in temp, or continue to rise, maybe beyond what is found typically in brewed.

If your PF is cold, it may not be letting the puck get up to typical brew temp on the first shot, brew-wise this may be abnormally cool, rather than the 3rd/preheated shot being abnormally hot.

I'm confused, you say you saw a definite effect, but not in taste?


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## ajohn (Sep 23, 2017)

More strength of taste rather than the actual taste / flavour. Not easy to differentiate but that was my impression.

John

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## Wajid (Apr 24, 2018)

Thanks @MWJB - I tried a brew with 21g in 400mL at 92oC for 6 minutes (because I couldn't trust myself to know what bitter was for a moment) but the thing was undrinkable.

I might take your advice and try a medium grind of 24g in 400mL at 90oC for 4 minutes and see...

This morning's 24g in 400 at 84 for 1m30s was OK but sour - I think with the 24g I'm hitting that ratio of 1:16.6667 which is most awesome.

I don't want to just pack it in and blame the beans, but there might be a bit of that variable in that they are most likely stale supermarket stuff... I know the pre-ground can make a lovely cup...


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## foundrycoffeeroasters.com (Jun 19, 2014)

We don't find a big difference when brewing at different temps for pour over. We just adjust other variables instead, mainly the grinder and brew time. Although we brew Aeropress at 85 degrees in the coffee shop, that's purely about being able to present it at closer to drinking temp - so brew time is increased to increase the extraction.


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## MWJB (Feb 28, 2012)

Wajid said:


> Thanks @MWJB - I tried a brew with 21g in 400mL at 92oC for 6 minutes (because I couldn't trust myself to know what bitter was for a moment) but the thing was undrinkable.
> 
> I might take your advice and try a medium grind of 24g in 400mL at 90oC for 4 minutes and see...
> 
> ...


How do you know the temperature you are brewing at, how are you keeping it constant for 6 minutes?

With an insulated steel press, 1:16.7 should be fine, ratio just sets the strength (for a given grind setting & steep time).

I don't believe it is possible to get a reasonable level of extraction in French press in 1:30, unless you grind extraordinarily fine - then you will have a silty & bitter brew.

You can brew for 50minutes+ at 24g:400g in a a double walled steel press.

French press is forgiving of beans, there's no flow, like with drip & espresso.

Once you have grind & ratio set the only variable is time...the longer you steep the more consistent brew will be.


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## Wajid (Apr 24, 2018)

I'm using a double-walled steel press (Espro-P7) which claims to lose less energy than a normal glass press, and so should keep the temperature from falling so quickly - though I haven't measured temperatures at the end of a brew.

But, based on what you've said, my ratio seems ok, so maybe a coarser grind would give better results.

As tomorrow is Sunday, I have 2 brews in mind: increase the coarseness to 550 on the Kinu, and then do 24g in 400mL at 84oC for 1m30s.

If that doesn't seem like progress then later on, with the same coarseness, 24g in 400mL at 84oC and brew for 30 minutes.


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## MWJB (Feb 28, 2012)

Wajid said:


> I'm using a double-walled steel press (Espro-P7) which claims to lose less energy than a normal glass press, and so should keep the temperature from falling so quickly - though I haven't measured temperatures at the end of a brew.
> 
> But, based on what you've said, my ratio seems ok, so maybe a coarser grind would give better results.
> 
> ...


550 is that 5.5 turns? Seems very coarse?

After a point, the coarseness will stop extraction at a fairly low level. There's nothing wrong with that as long as you find a balnce you like, but bear in mind that you will likely be tasting different stages of low extraction...if you get bitterness it is likely due to silt in the cup or under-extraction, rather than over.


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## Wajid (Apr 24, 2018)

@MWJB - yes that's right 5.5 turns (I've started using a different numbering system now, so 5.5 turns is recorded as 55 on my sheet)

Anyway, you're absolutely right about the coarseness and the length of time to brew for. I tried a longer brew with slightly finer grind at 45 which was great!

More generally, I found that darker roasts like lower temps and lighter roasts can tolerate higher temps (however, pinch of salt because my results are with different bean varieties, not the same green bean roasted to different levels). I've tried 2 types of dark roast and 3 types of lighter roast.


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