Good Extraction

eNtHus

Hi All

Been making coffee for couple of years now. However, I still have a doubt regarding a good extraction. What is good extraction? How can you tell/see a good extraction? Sometime I make the grinder fine to get the water flow through it slow so get a lot of crema in the coffee. This tend to make dark brown spot around the edge. Is this a good shot. Is there any guide/pictures to show a good shot? Thanks.

nzroaster

At the end of the day, its what the espresso tastes like that is important above all else. When the coffee is pouring you should see a nice straight hang from the spouts. The speed of the pour should be consistant (ie not speeding up or slowing down) and the colour should be dark red through to hazel brown. This will ensure that the coffee is extracted evenly. The shot should take 20-30 seconds to pour. Looking at the espresso and crema there are a few things to look for. If there are dark spots of black/brown it means that you have pulled a tight shot, this is no reference to good or bad. If there is any light brown or yellow spots it means that you have overextracted the coffee, this is bad. There is nothing wrong with pulling tight shots as long as you a) don't overextract the coffee by having it pour too slow and b) are still getting the 25-30ml extraction. The taste of the espresso should be balanced. It should be sweet and rich and you should be able to taste it all around your mouth. It should have a good body (the difference between water and syrup) and a pleasant aftertase. If it is under extracted it can have a metallic taste and have the consistency of cardboard in your mouth. If it is overextracted it can have a bitter taste and be very sharp. It is possible to both over and under extract the same shot, this is a result of poor distribution. Of course, these are just guidelines and depends on the coffee you are using and what you are trying to achieve with it.

eNtHus

Thanks for you prompt reply. One question, I believe the overextract shot is when the water has finished extracted the caffeine in the coffee? Is this correct? So if I have a tight shot and I stop right before the yellow/light spot coming out. The shot should be quite good, is the correct?

psaigh

The idea of a good shot is subjective.  A shot that tastes watery and acidic to me (for example), might be great for you, and so i would deem it as a bad shot whereas for you, it was probably great.  Also, there is no golden rule for extracting the 'perfect' espresso, it's blend, machine and person specific. Having ranted on about that when i get a new blend to play around with i start with a general rule of extracting a 25ml shot in 25 seconds, i find this (in general) tends to best represent the flavours that i enjoy most from a good shot of espresso.  To acheive this i use the following parametres; 16grams of fresh ground coffee in a double basket.  Bar pressure at 9. water temp at 203.5F(where available).  Pre infusion set to 2-3seconds(where available).  15kg's of even pressure using standard collapsing method of dosing.  Then after nailing these parameters and tasting the shot i tweak them all accordingly until i find the flavour profile that i feel works best for that particular coffee. If your coffee is fresh and your machinery up to scratch, in general your shots should look like warm, chocolate tinted honey drooping or glubbing from the portafilter.  The color should air further towards a reddish hue rather than brown and there really should be no blond or yellow streaks coming through (represents acidic flavour).  That spotting you spoke of is generally a good thing, though if excessive or particularly dark it could signify an over-extracted shot (you'll know straight away by tasting the espresso). The shot should start off quite dark and then drop a few shades in colour.  When it starts to blond or you start seeing yellow/white specks come through stop the shot immediately.  There should be a thick, viscous crema that reforms easily if broken apart (ie using a spoon etc) and lasts well over a minute. There are a number of good guides online, try: http://www.ineedcoffee.com http://www.espressovivace.com/archives.html http://www.coffeegeek.com/opinions/barista/10-14-2006 http://www.coffeegeek.com/opinions/alanfrew/02-23-2002 and check out youtube for hundreds of 'perfect shots' Having said all that just keep tasting!  All those guides etc. serve their purpose as being, um, a guide.  however, to find a trully great shot for you, just keep tasting.  Hope this helps a little.  Feel free to pm me if you have any questions.

psaigh

I believe the overextract shot is when the water has finished extracted the caffeine in the coffee? Is this correct?

Overextracting coffee has nothing to do with caffeine content, but instead flavour compounds and oils.  It's when the oils are (over)extracted in such a way as to unbalence the flavour profile skewing it masively more bitter

So if I have a tight shot and I stop right before the yellow/light spot coming out. The shot should be quite good, is the correct?

You should always stop the shot right before the yellow/light spot is coming out.  With a particularly tight shot (a restretto for example) you will probably stop the shot well before any blonding occurs.

eNtHus

I sometime heard that my short black is burned. Is there such thing? Can you burn the shot? Is burn equal to over-extraction?

psaigh

There certainly is and does not refer to over or under-extraction.  This usually happens if the water temp hitting the head is too high.  This can be a result of the boiler temp being set too high for the particular blend (or alternatively the temp at the heat in the case of heat exchange machines) or if the machine sits idle for too long between shots. It can also occur if (esp. in the case of up-dosing) the grounds in the portafilter come into contact with the hot shower screen for too long (ie/ a second or two) before waterflow and hence extraction occur. If you get this remark occasionally make sure you purge 30mls (or so) of water out of the grp head when you remove the portafilter to start dosing to stabalise the water temp. If you get this remark quite often talk to your technition/roaster to adjust the water temp in the machine to better suite your coffe blend.

GrindOnDemand

Just to add another point to psaigh's explanations for undesirable burnt flavours, it can also occur if the groups are not purged/cleaned out regularly (sometimes referred to as backwashing or 'blind cleaning').  A build up of residual grind in the group will taint any freshly ground beans that come in contact with it as extraction occurs. So ... clean your groups regularly, & heed psaigh's comments, & hopefully the burnt flavours will disappear!

eNtHus

Thanks for reply. I always purge my group and we clean the machine every single night. Good thing is this only happens in blue moon. My last question, any suggestion to keep pouring a good shot every time? Is this possible?

askthecoffeeguy

Absolutely its possible to pour a great shot every time, because any time you are unhappy with the extraction for any reason you should reject the shot, make changes to the grind / your technique as necessary, and start again If you haven't done so already try talking to your coffee roaster about getting the best out of your grinder and espresso machine.  They should be able to set up both for optimal performance. And if not, you should really consider if you are getting the best service possible, and value for money, out of your current supplier. This does not absolve you from researching your product, however, you should dig and mine every avenue possible, until you know what a 'god shot' is, and are confident that you can produce one with reasonable consistency In fact, perhaps the question you should be asking yourself is: Is every shot a 'god shot' and if not, why not? Cheers, Pat

espressomesso

There certainly is and does not refer to over or under-extraction.

askthecoffeeguy

at my work we purge before every extraxtion

psaigh

I think the secret to acheiving a great shot everytime comes from controlling all of the variables, every time.  By using a high end machine, that controls most of your heat issues (no temp. surfing needed) matched with a good quality grinder.  That all has to be backed by a consistant dosing and tamping method.  And finally, using great quality coffee supplied from a supurb and consistant roaster (beleive me, this can be very hard to find). Then if a bad shot does come through, to find out why, lock all your variables save one, play around with that.  If that doesn't help pick another and lock every other variable (as much as possible) and continue until you find the reason why you had a bad shot.  Go back to your basics, and take baby steps to suss out the problem.  Tools like the naked portafilter, the espro tamp and even those auto tamps are great for trouble shooting a bad shot. With time you'll develop a sixth sense for why a shot didn't pull through the way you liked it to, but to begin with, be as systematic as possible! Also remember to taste your bad shots.  I know its not fun but it's invaluable to know what an underdosed shot tastes like compared to one where the water temp was too high, or the boiler pressure dropped slightly, etc etc.