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Thread: How do you distinguish sour from acidic?

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    How do you distinguish sour from acidic?

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Ive been wondering about how youd distinguish a sour shot (result of underextraction or low temp) from an acidic one? Or are they one and the same thing?

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    Senior Member Dennis's Avatar
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    Re: How do you distinguish sour from acidic?

    From my understanding the term sour is generally how we tend to describe the taste of things that are acidic. *

    In terms of sour tasting coffee, this seems to be used to describe something unpleasant. *Like wine, a certain level of acidity in coffee can also be desirable.

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    Senior Member flynnaus's Avatar
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    Re: How do you distinguish sour from acidic?

    I think the term bitter is more appropriate when describing what you are calling sour tasting coffee. But bitter is also not necessarily negatiive e.g. bitter beer

    Perhaps we should just use the scientific terms bad or crappy

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    Re: How do you distinguish sour from acidic?

    Hmm... I dont think you can call sour coffee, bitter - theyre very different things to me. Ones like sucking a lemon, the other is like sucking a Panadol tablet.

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    Re: How do you distinguish sour from acidic?

    I suppose the reason Im asking is, some african varietals are known to be acidic and that contributes to them cutting through milk very well. When tasting them as espresso, they arent necessarily bad (being acidic) and could even be described as fruity or having a lemony zing. What Im asking is, how do you distinguish that to a shot that is made when the brew temp is too low? At the moment, I only know one shade of sour, and its .... sour.

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    Re: How do you distinguish sour from acidic?

    NTE,

    Methinks youve answered your own question ... sourness is particularly noticeable on the palate as an espresso when the extraction temp is too low - regardless of the beans used.

    However, when the temp is optimal (for me 8.5-9 bar), sourness is not evident, but the intrinsic acidity of the bean/beans ground & extracted will always come through (especially if it has a high acidic character - like, as you noted, some Africans).

    My commercial roaster recommends approx 8 bar for the blend I like to use, supposedly because the bean blend used is low in acidity (predominantly dry processed Indo & Indian beans, with a sprinkle of Sth Americans, I suspect ::).

    I disagree, & have had disagreed umptime-times.

    I get the best out of his beans from 9 to 9.5 bar, & cutting the shot short.

    I minimise my extraction times accordingly, so over-acidic blonding doesnt taint the flavours of the espresso base

    Up the temp of your pump to adjust the pressure stat & monitor the gauge NTE if thats the prob mate!

    Sourness? Low temp in the heads, or under-extracted.

    Acidic? The nature of the bean.

    Cheers,
    Tony

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    Re: How do you distinguish sour from acidic?

    Perhaps I didnt better explain, to me, I only know one shade of sour, and I taste acidic as sour as well. The only reason I said africans were acidic was not because I tasted them to be acidic, but because they were described as being acidic (which tastes sour to me). So, if I cupped an african, how would I know if the sour Im getting is the nature of the bean or poor extraction?

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    Re: How do you distinguish sour from acidic?

    Hi NTE, I guess the best way to tell sour from bitter would be to go to the shop buy some No Doz tablets crush 1 of these up in water and taste it, remember how it feels on your tongue i.e. where on your tongue you get the taste front,back, side or roof of your mouth this will be a bitter taste. Next get some citric acid and disovlve in water and do as for the No Doz this will be a sour taste.
    Thats my 2 cents worth.
    Marty

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    Re: How do you distinguish sour from acidic?

    Hmm, this is a question that is very hard to answer in writing, but Ill try my best. It would be so much easier through a cupping explanation.

    First off, sourness and bitterness are 2 different things. 2nd Acidity is not what makes espresso cut through the milk better. Let me try to explain, hopefully consisely.

    Everyone can taste coffee, some better than others, but it is out of your control how much you can taste (to a certain degree) and you cannot train yourself to taste better/more. What most people have trouble with is discribing what they are tasting. This is something you can work on and by exposing yourself to more flavours and mentally noting them, you can become a better taster (which is really a better flavour describer).

    The most important thing to remember is that there are 2 components to keep in mind when tasting and describing coffee.
    The first part, which is easier to distinguish is mouthfeel. Mouthfeel is essentially the old tounge map we were taught in school. Sweet, Sour, Bitter etc. As you become more in tune with your mouth, you will be able to break down sections of your tongue into more specific areas. To start with lets use the basics, Sweet - front, body - middle, bitter - back, sour - sides, finish - entrance to throat, acidity - roof of mouth. These are the first areas to concentrate on.
    Sweet, sour, and body are easy to pick out. Finish is fairly easy but if you are having trouble, breathe in after you swallow the espresso. * acidity or brightness is the feeling when the flavour sparks to the top of your mouth.
    If you can describe coffee based on mouthfeel you are doing well. Mouthfeel is not just 1 dimensional though. By identifying the specific areas in your mouth, you can also describe the way flavours move in your mouth.

    The second component is flavour. This is where it gets trickier. The only way to describe flavour better is to be more aware of everything you put in your mouth. Your sense of taste is very close to your memory banks in your brain so the more you taste things and remember them, the better you will be able to describe these flavours in other things, such as coffee. Flavours can be a combination of mouthfeels and are independant of the mouthfeel. What I mean by this is that if you eat a sour apple, the flavour is sour apple, but you may not taste this on the sides of your tongue only. You can taste that apple has sweetness, sourness, acidity, and body, with varying degrees of stregnth of each. By being able to identify these concentrations in your mouth is a key area to being able to describe the flavour. hence why mouthfeel is very important. For example, fruityness is a certain combination os sweet, sour, acidic (my memory is failing a little here) but this is why a fruit flavour can be artificially recreated.

    To answer your question (if it was) about african coffees being acidic, roast an ethiopian to a medium colour (before 2nd) and roast a south american to the same colour. The south american will be smooth (balance of body, sweetness and low acidity) where as the african will be sharper (sweet, body, acidity). This does not mean it will be sour, and you can still have a great balanced coffee with both.

    Something else to consider is the roasting process. As you roast coffee from 1st crack to long into rolling 2nd the following process occurs (warning: heavily simplified). 1st crack -> bean is highly acidic -> acids turn to sugars (sweetness) -> sugars caramalise (body) -> caramels burn (ashy). So the acidity in the green bean (amongst other factors) will depend on how we can roast it. This is why a colombian taken into rolling 2nd tastes like an ashtray, where as a Kenyan at the same level is still sweet and smooth.

    To answer your question regarding acidic coffee vs underextrated/low temp/pressure, this is where an experienced cupper can come in handy. There is a difference between un underextracted coffee and an acidic coffee. (keep in mind we can manipulate what flavours we want to extract from a coffee). Try a tradtitional cupping of the coffee to see if it is sour.

    In terms of flavour cutting through the milk this can be done by a number of things.
    1) increase the ratio of coffee to milk
    2) increase the stregnth of the coffee (stregnth = dilution, so double ristretto is stronger than espresso)
    3) use a fuller bodied or stronger finished
    4) use a contrasting coffee (sweet coffee and sweet milk blend, bitter and darker roasted coffee contrast the sweet milk)

    Unless you are confident with your barista ability and home roasting ability I would not worry about .5 bar brew pressure just yet. You can manipulate your espresso flavours by playing around with your grind/dose relationship.

    When I started to learn to cup this was the advise I was given.
    1) You already know how to taste coffee, you just need to learn how to describe it.
    2) Start by taking what you know and split it in half. eg.
    * * * * * * * * * *a) this tastes like coffee
    * * * * * * * * * *b) this tastes like coffee I like / this tastes like coffee I dont like
    * * * * * * * * * *c) I like this because it is sweet, sour, acidic, bitter, has finish etc.....
    * * * * * * * * * *j) this is fruity -> stone or citrus?
    and so on.
    The person who gave me this advise has been cuupping coffee for 20 years, and tea for 15 before that. He could tell if the water used in the cupping was boiled once or twice. That is my goal with cupping, to get to that point.

  10. #10
    Sleep is overrated Thundergod's Avatar
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    Re: How do you distinguish sour from acidic?

    a) and b) were easy for me.
    Progressing beyond that has been my problem.
    Ive advanced a very, very, little bit.



    P.S.
    No need to have worried PR, that was well written.

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    Re: How do you distinguish sour from acidic?

    WOW! Great reply PR, now Ive got something to progressively work with for the next 2 [s]weeks[/s] [s]years[/s] decades... Thanks guys.

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    Re: How do you distinguish sour from acidic?

    Gday,

    Firstly, I should say that I am by no means an experienced coffee cupper, though I have been learning the same (tasting) skills through beer and wine tasting for a couple of years - now moved to coffee as well.

    I totally agree with the comment that cupping is a linguistic art, not a sensory one. Its all about learning what words best fit what youre tasting, not learning to taste new things. Personally, I think what that means is that ANYone can cup coffee, they just need to practise it. For example, I have a friend who prefers to "draw" the flavour of a coffee rather than to describe it using words. He draws a simple graph to show the intensity of the low-, middle- and high-end flavour components.


    PR - I was a bit confused by your definition of mouthfeel. To me, mouthfeel is the physical sensation of the coffee in the mouth. This includes body, and also texture (ie. smooth or astringent), but doesnt include actual flavour components (acidic, bitter, sweet etc.). Of course, certain flavours are linked to mouthfeel; for example, certain coffees with a higher acid component tend to have a "cleansing" effect on my palate, meaning that they finish "clean" (part of mouthfeel) and could be described as being light bodied. This is all IMO and Im open to corrections.


    Also, I know you gave the disclaimer: "warning: heavily simplified", but would you mind elaborating on your description of how the roasting process effects flavour components? The thing that confused me was the line "acids turn to sugars". Ive read very little about the chemistry of coffee roasting, but I would imagine that the basic reactions occurring are similar to roasting malt (for beer) - which I do know about. Its starches and other carbohydrates that break down into sugars, which then caramelise. Acids hasten caramelisation, I believe, as well as being involved in Maillard reaction which constitutes the browning of malt (and beans) and produces flavour components - so the prevalence of acids in the bean MUST effect the sweetness/sugar profile of a roasted bean. Again, Im not that clear on any of this myself. Any thoughts?


    Great post, anyway! Hope my questions of clarification arent too taxing.
    Cheers
    Stuart.

    ps. NtE - this link might help? Dont know how reliable it is... http://www.coffeeresearch.org/science/sourmain.htm

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    Re: How do you distinguish sour from acidic?

    Quote Originally Posted by stuartgrant link=1218074243/0#11 date=1218162250
    *
    PR - I was a bit confused by your definition of mouthfeel. To me, mouthfeel is the physical sensation of the coffee in the mouth. This includes body, and also texture (ie. smooth or astringent), but doesnt include actual flavour components (acidic, bitter, sweet etc.). Of course, certain flavours are linked to mouthfeel; for example, certain coffees with a higher acid component tend to have a "cleansing" effect on my palate, meaning that they finish "clean" (part of mouthfeel) and could be described as being light bodied. This is all IMO and Im open to corrections.
    this is exactly right. What I meant by sweeet, sour, bitter etc. is the part of the tongue that most of us would have learnt in school. Its not that the front of the tounge is sweet, but it is where we taste a higher concentration of sweet flavours. But what you said is spot on, mouthfeel = sensation.

    Quote Originally Posted by stuartgrant link=1218074243/0#11 date=1218162250
    Also, I know you gave the disclaimer: "warning: heavily simplified", but would you mind elaborating on your description of how the roasting process effects flavour components? The thing that confused me was the line "acids turn to sugars". Ive read very little about the chemistry of coffee roasting, but I would imagine that the basic reactions occurring are similar to roasting malt (for beer) - which I do know about. Its starches and other carbohydrates that break down into sugars, which then caramelise. Acids hasten caramelisation, I believe, as well as being involved in Maillard reaction which constitutes the browning of malt (and beans) and produces flavour components - so the prevalence of acids in the bean MUST effect the sweetness/sugar profile of a roasted bean. Again, Im not that clear on any of this myself. Any thoughts?
    I must admit, the science of this is not something that resides permanently in my brain and it sent me searching for my "Sience of Espresso" book by Dr. Illy, which I realised is out on loan.

    But yes, the acidity levels in the bean do effect the amount of sweetness and in turn caramalisation that a roaster can manipulate from a bean.

    Perhaps Luca or someone can jump in with the scientific explanation before my book is returned.

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    Re: How do you distinguish sour from acidic?

    Geez Jason, when are you going to organise a full-on, comprehensive cupping session up here (CS cost-incurred based, of course) to delve into & debate such complexities like the subtleties of taste sensations felt in different parts of the mouth that youve highlighted?

    Youve a few SOs in stock to cup, so whaddya reckon?

    Ive been yearning for a local roaster to offer such ... but :(, alas ...

    Last cupping up there was the Cuban ... our own, & yours. Not fully educational, because we were comparing each others dodgy home-roasts! ;D Apart from yours that came up trumps, of course.

    ... Tony






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    Re: How do you distinguish sour from acidic?

    We will do something soon Tony.

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    Re: How do you distinguish sour from acidic?

    Quote Originally Posted by Pioneer Roaster link=1218074243/0#14 date=1218170734
    We will do something soon Tony.
    Why donít we catch and hold 2 birds in one hand and incorporate a cupping workshop with the next QLD roast off competition

    Just a thought
    As I missed out on the last roast off

    KK



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