# Acidic shot help!



## fatboyslim (Sep 29, 2011)

Hi coffee lovers,

So just when I thought I'd mastered grinding, dosing, distributing, tamping; I switch to some older beans and suddenly I can't avoid making overly acidic shots.

I've tried making the grind coarser but even minute adjustments make extraction times slightly too short. Could it be an over-tamping issue?

I've got a Gaggia Baby so no real way to adjust temperature or pressure either.

Please help!


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## jimbow (Oct 13, 2011)

Overly acidic or sour tasting espresso is usually a sign of under extraction. Try grinding finer and if you find the pour takes too long (longer than 25 - 30 seconds) then lower the amount of ground coffee slightly to compensate.

This post has some good troubleshooting tips:

http://www.home-barista.com/tips/espresso-101-how-to-adjust-dose-and-grind-setting-by-taste-t16968.html#wrap


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## fatboyslim (Sep 29, 2011)

Thanks a lot jimbow, that guide is exactly what I was looking for.

I was lead to believe grinding finer gave a more acidic shot due to a greater number of 'fine' particles that are the first to be extracted and give rise to acidity, lengthening the acidic stage of extraction.

However as you say, overly acidic shots are caused by underextraction which seems contrary to that.

I tried dosing less today, actually less than 16g as I pushing a load off when distributing. Definitely some improvement so I guess I just need to keep tweaking.

Thanks again.


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## MonkeyHarris (Dec 3, 2010)

It also depends a lot on the roast of the beans. I find lighter roasts are way more acidic than the darker ones (play havoc with my heartburn).


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## ChiarasDad (Mar 21, 2010)

This also could mean that your thermostat is dying, causing your shots to be too cool. (This happened to me a year or so ago, so I am not being utterly hypothetical.)

One way to tell would be to turn the steam switch on for a few seconds (perhaps 5, perhaps 10, but surely not much more) and then switch it off before pulling your shot. If that fixes the sourness, then you have a temperature problem and a new thermostat (or a PID, thought I forget whether the Baby can accomodate them) may be what you need.


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## jimbow (Oct 13, 2011)

Good point. I wonder, would raising the brew temperature, even artificially by using the steam switch, increase the rate of extraction and possibly offset any under extraction caused by coarse grind, light tamp, low dose, etc?


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## RolandG (Jul 25, 2010)

sourness from too low a temperature is generally because of different flavours extracting at different temperatures - the coffee can be overextracted and still sour if it's because of temp







as far as I know, slightly higher temp shouldn't impact extraction speed much (?), but would risk scorching the coffee and getting burnt/bitter flavours.

Fatboyslim - What are you using to determine when you stop your shot?


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## jimbow (Oct 13, 2011)

Interesting. I must admit, I always thought of temperature as simply one of the variables controlling extraction and did not really consider a more fundamental effect on the extraction. I think I need to think about this for a while as it is quite a change from how I have always viewed the extraction process. My mental model of espresso extraction was always that the coffee solids and oils in the ground coffee are dissolved in the brew water. I always imagined that if the water was hotter, the solubles would dissolve more quickly in a similar way to when salt or sugar is dissolved in water.

I believed that different flavour compounds dissolve at different rates with the fruity, acidic tasting compounds dissolving most quickly, then the caramels and sugar compounds followed finally by the bitter tasting compounds. I believed this was why under-extracted coffee tastes sour - it is not that there are more acid tasting compounds dissolved in the under-extracted espresso, but rather less of the slower dissolving compounds which would normally balance out the acidic taste.


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## RolandG (Jul 25, 2010)

jimbow said:


> I believed that different flavour compounds dissolve at different rates with the fruity, acidic tasting compounds dissolving most quickly, then the caramels and sugar compounds followed finally by the bitter tasting compounds. I believed this was why under-extracted coffee tastes sour - it is not that there are more acid tasting compounds dissolved in the under-extracted espresso, but rather less of the slower dissolving compounds which would normally balance out the acidic taste.


I believe that's correct. But although under-extracted coffee is sour, not all sour coffee is under-extracted







My thinking is that if low temperature caused sourness via under-extraction, simply pulling a longer shot or changing grind would allow you to compensate - which I don't believe is true. That suggests that more than a blanket under-extraction is happening if temperature is too low.

I suspect the first description I saw of this explanation was in Scott Rao's "Everything But Espresso" (talking about filter, but not fundamentally different I would think).

P. 2

"Higher extraction temperatures result in higher extraction rates because most compounds are more soluble at higher temperatures. Temperature affects flavour as well because the relative solubility of various compounds changes at different temperatures."


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## fatboyslim (Sep 29, 2011)

This discussion is very interesting and informative. There is nothing wrong with the temperature, as I said originally I really did hit the sweet spot with some freshly roasted beans. I'm fairly certain I can keep temperature constant through all extractions.

Having hit that sweet spot, I was fairly confident I'd controlled all the variables. I use a calibrated espresso glass which indicates 1oz, 1.5oz and 2oz but I don't pay much attention to it actually.

I observe the flow and colour during extraction and stop it when the flow starts 'blonding'.

The problem was when I switched to some much older beans. I believe I have solved that problem by dosing differently.

However I tried some different freshly roasted beans today and had to wait about 10-15 seconds from turning the pump on, to anything appearing out the spouts.

Dosed less and grinded coarser which gave a satisfactory taste but the extraction was too fast by all measures. Grinding finer to increase extraction time caused a big delay from switching the pump on to the flow exiting the spouts.

Should I try dosing even less?

It appears the freshness of the beans is the factor I'm struggling to understand here. At least my shots aren't all that acidic anymore.

Thanks for the tips and info


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## fatboyslim (Sep 29, 2011)

This discussion is very interesting and informative. There is nothing wrong with the temperature, as I said originally I really did hit the sweet spot with some freshly roasted beans.

Having hit that sweet spot, I was fairly confident I'd controlled all the variables. I use a calibrated espresso glass which indicates 1oz, 1.5oz and 2oz but I don't pay much attention to it actually.

I observe the flow and colour during extraction and stop it when the flow starts 'blonding'.

The problem was when I switched to some much older beans. I believe I have solved that problem by dosing differently.

However I tried some different freshly roasted beans today and had to wait about 10-15 seconds from turning the pump on, to anything appearing out the spouts.

Dosed less and grinded coarser which gave a satisfactory taste but the extraction was too fast by all measures. Grinding finer to increase extraction time caused a big delay from switching the pump on to the flow exiting the spouts.

Should I try dosing even less?

It appears the freshness of the beans is the factor I'm struggling to understand here. At least my shots aren't all that acidic anymore.

Thanks for the tips and info


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## MikeHag (Mar 13, 2011)

Seems to me you're making life difficult for yourself, bud. Older beans will taste different from newer beans and there's not a lot you can do to make old beans taste and react like new, fresh ones.

Very fresh beans will naturally create problems in achieving a consistent espresso extraction due to their still containing a lot of gases. Some shots will run quick, some will run slow or even clog (as you've found), some will start slow or as drips and speed up to a gusher... etc etc. That's why people usually leave the beans to degas for a few days after roasting... they become more stable for espresso. Sure, you can get a good shot from extremely fresh beans, but can you repeat it? Unlikely. The beans will continue to change over the days and weeks following roast. They will keep degassing, and they will also suffer from oxidation and gradual staling, all of which will affect flavour and extraction. Basically, you'll get different results every day and you need to adjust the grind accordingly... you'll also get different results throughout the day as the beans in the hopper react to changing environmental conditions such as humidity, taking in and releasing moisture and therefore resulting in a different grind. They key is constantly monitoring the mousetails and frequently tweaking the grind to keep the shot as consistent as possible. Aim to keep the extraction time the same, the dose the same, the temperature the same, the weight/volume of beverage the same - although this is difficult and part of the challenge and balancing act of a barista. It eventually becomes impossible, and then it's time for fresh beans again.


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## garydyke1 (Mar 9, 2011)

fatboyslim said:


> The problem was when I switched to some much older beans. I believe I have solved that problem by dosing differently.
> 
> However I tried some different freshly roasted beans today and had to wait about 10-15 seconds from turning the pump on, to anything appearing out the spouts.
> 
> ...


Generally if you decrease the dose you grind finer to compensate, however as Mike points out - fresh versus stale beans are chalk and cheese. Sometimes stale beans give a better cup increasing the dose and grinder courser..but this is trial and error TBH


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## MikeHag (Mar 13, 2011)

As an aside regarding acidity (although I'm not absolutely sure whether you mean acidity or actually sourness, OP) here's a quote from Mark Overly's blog, a roaster in the US.



> Coffees coming from technified plantations are thin, acidy, and flavorless due to the low nutrient quality of their environment. Pumping nitrogen fertilizer into poor soil conditions and highly variable temperature conditions does not make for good flavor quality.


I do wonder whether the acidity that is so sought after in present times is little more than marketing spin designed to encourage buyers to unwittingly adopt automated growing solutions despite the potential disadvantages in the cup. If so, it would be the great coffee swindle









(Oh crap, more controversy







)


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## garydyke1 (Mar 9, 2011)

fatboyslim said:


> The problem was when I switched to some much older beans. I believe I have solved that problem by dosing differently.
> 
> However I tried some different freshly roasted beans today and had to wait about 10-15 seconds from turning the pump on, to anything appearing out the spouts.
> 
> ...


Generally if you decrease the dose you grind finer to compensate, however as Mike points out - fresh versus stale beans are chalk and cheese. Sometimes stale beans give a better cup increasing the dose and grinder courser..but this is trial and error TBH


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## jimbow (Oct 13, 2011)

Are the two sets of beans you are using (older and fresher) both of the same type of bean? As Mike and others have said, freshness makes a big difference to how the coffee brews. You are probably aware that the type of coffee makes a big difference too; you will probably need to change grind and dose whenever you change to a different type of bean.


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## fatboyslim (Sep 29, 2011)

jmbow its Taylors Espresso blend so its always blended to the same profile but won't always have the same beans in.

I tried extracting some beans literally hours after production. Thats probably my first issue, good taste though.

Using the older beans I think I was dosing too much, not entirely sure (and I don't remember) which grind setting I was using but dosing less definitely improved flavour.

As for this general statement 'Generally if you decrease the dose you grind finer to compensate', is there a widely regarded 'standard dose'?

Or is it based on extraction time, extraction problems and flavour, unique for everyone?


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## garydyke1 (Mar 9, 2011)

fatboyslim said:


> As for this general statement 'Generally if you decrease the dose you grind finer to compensate', is there a widely regarded 'standard dose'?
> 
> Or is it based on extraction time, extraction problems and flavour, unique for everyone?


I use a VST 14-15-16G basket & will dose based on the results im getting usually 14.5-15g. Biggest improvement to my espresso shots and can highly recommend. You do have to grind quite a lot finer

Old style baskets are a distant memory now, ....


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## fatboyslim (Sep 29, 2011)

gary I'm a very scientific bloke and quite frankly your precision, firstly terrifies me and secondly just seems to take some of the flare out of barista-ing.

No doubt precision has its benefits but was it really a significant difference using old style baskets (I presume you mean non-pressurised, just standard filter baskets) and VST with such specific weights?

If so tell me more... Always willing to learn what must be logical progress before I elude to it myself.


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## seeq (Jul 9, 2011)

Precision is vital in coffee making, half a gram actually does make a noticeable difference in the taste, just like 1c temperature difference in the water does. It took me some time to really notice, to start with I hardly noticed the difference between a sweet shot and a bitter shot, despite the difference of about 15 seconds in extraction times. But vary each parameter one at a time by a fairly large amount, then narrow it down to personal preference. For me it varies with the beans. For example I get my best shot of jailbreak from 16g, Blake mkiii I prefer 18.5g, that's my preference, others will be different. experimentation is the key to success.


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## garydyke1 (Mar 9, 2011)

fatboyslim said:


> gary I'm a very scientific bloke and quite frankly your precision, firstly terrifies me and secondly just seems to take some of the flare out of barista-ing.
> 
> No doubt precision has its benefits but was it really a significant difference using old style baskets (I presume you mean non-pressurised, just standard filter baskets) and VST with such specific weights?
> 
> If so tell me more... Always willing to learn what must be logical progress before I elude to it myself.


VSTs are design for specific doses. 0.5g makes a big difference to the end result.

Im not interested in flare, more about refining my processes to get the end result I want


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## garydyke1 (Mar 9, 2011)

seeq said:


> Precision is vital in coffee making, half a gram actually does make a noticeable difference in the taste, just like 1c temperature difference in the water does. It took me some time to really notice, to start with I hardly noticed the difference between a sweet shot and a bitter shot, despite the difference of about 15 seconds in extraction times. But vary each parameter one at a time by a fairly large amount, then narrow it down to personal preference. For me it varies with the beans. For example I get my best shot of jailbreak from 16g, Blake mkiii I prefer 18.5g, that's my preference, others will be different. experimentation is the key to success.


Couldnt agree more


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## RolandG (Jul 25, 2010)

on a quick clarification point, VST baskets aren't pressurised - they are like standard baskets but machined to a higher standard. I've had a chance to play and have been rewarded with tastier shots in comparison against standard baskets.

I agree with Gary & Seeq - small differences can make a huge difference in the taste. That said, don't let it fool you into being entirely scientific and predictable - no matter how much information you know about the shot, you can never be certain how it'll taste until you try it









Dosing isn't standard - it varies with personal taste, what machine you are using, what beans you are using, etc. For most people, 16g-ish is a good starting point. Try lower and higher doses and see what works for you. I only suggest never ruling anything out - just experiment and see what effect it has.


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## MikeHag (Mar 13, 2011)

fatboyslim said:


> gary I'm a very scientific bloke and quite frankly your precision, firstly terrifies me and secondly just seems to take some of the flare out of barista-ing.
> 
> No doubt precision has its benefits but was it really a significant difference using old style baskets (I presume you mean non-pressurised, just standard filter baskets) and VST with such specific weights?
> 
> If so tell me more... Always willing to learn what must be logical progress before I elude to it myself.


Whilst I agree with others that flare comes from a good quality drink rather than from tattoos, twirly taches and titanium tampers, what is necessary and what is not necessary ultimately comes down to the individual's aims or needs. People newer to the world of the barista have more humble aims and needs than people who have been doing it longer.

On the one hand, when you see extreme precision from some of us on here, and excitement at having left behind certain tools, techniques or practises, bear in mind that this is a labour of love for many people, and our aims are to attain the absolute pinnacle of espresso. The God Shot. Espressissimo. In Maslow's Heirarchy of Needs, we want the top of the triangle... self-actualisation.

But on the other hand, please don't think it's a case of people saying "everyone should now be doing it his way". You might be recommended such, but it's also perfectly ok to want less precision, to need more convenience, to be less OCD.

Re the VST baskets, is there an improvement upon upgrade from a standard basket to a VST basket? Yes, if you know how to take advantage of it. Is it huge? No, in my opinion. Put it this way... as far as I know they don't use them in the World Barista Championships.


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