when people first start making espresso they usually just grind the coffee tamp it and then
move on with life blissfully unaware of the deep nerdy rabbit hole that they just avoided
then one day they see someone performing some weird ritual on the coffee grounds and they think
"they look like they know what they're doing, maybe that's what i've been missing this whole
time" and just like that they have been sucked into the black hole that we call distribution
today we want to back it up and find out if you really need a special tool or a certain
technique to distribute the coffee let's see what we can find out right after this
hey it's josh from the coffee science and education centre
today's video is a part of a series where we answer the most common questions we get about
science and the technique of espresso coffee last time we covered questions about tamping but today
we're going to take a closer look at what baristas call distribution distribution is the process of
preparing the ground coffee before we compress it using a tamp the thinking here is that if coffee
isn't evenly distributed throughout the basket then the water will work its way through the less
dense parts causing uneven extraction of from that bed of coffee in simple terms
water is lazy and it will always look for the path of least resistance through the
coffee evenly distributing the grounds is one of those ways that we try to make sure
the water can't just take the easy option out now there are a crazy number of tools
and techniques to help baristas distribute coffee so we wanted to see if we could find
any evidence that one or more of these techniques made a more significant difference than another
for the sake of time and our own sanity we could not test every method or tool out there
instead we limited our test to the techniques and tools most popular and used in today's cafes
these methods are collapsing the coffee bed vertically like by tapping the handle on the forks
of the grinder or the edge of the bench tapping the side of the basket with your palm we tested
both a short version and a longer version of this method the stockfleth technique a method that
involves shifting the ground coffee in a circle of motion between your first finger and your thumb
the ocd distribution tool that is a device which has a series of machined fins designed to move the
layers of coffee in a circular motion inside the basket and we also tested doing absolutely nothing
at all now before we get carried away i should clarify that these tests are not the final word
on what's best there are hundreds of variables that go into making coffee that we cannot account
for not to mention different taste preferences so your results may vary also things are about
to get really nerdy really quick so hang in there and seriously are you ready for this
we got one of our chemical engineers johnny to set up a series of different tests which include
measuring the differences in the espresso extraction time and also the tds tds means
total dissolved solids and that is inside the liquid espresso this is essentially a measure
of the overall strength of the espresso we do this by taking a small sample and measuring it with a
device known as a refractometer again the purpose of choosing these measurements was to see if a
particular distribution technique changed how the coffee extracted or the consistency of the shots
over time of course we also tasted the coffee but the results of our taste test were inconclusive
so we won't muddy the waters by commenting on taste this time around
let's start with extraction time the simple palm tap the stockfleth the ocd and undistributed
method all extracted in very similar ranges of time the palm tap and the stockfleth methods were
very ever so slightly more consistent than the ocd or the undistributed method but there were
basically nothing in the split of the results what was more interesting was that both the vertical
collapse and the longer palm tapping technique took noticeably longer to pour in that extraction
than the other methods used our best guess is that the most aggressive downward force is causing some
of those finer particles to move downwards and choke the flow of water just a little
now even though the water is taking longer to flow through the coffee the vertical collapse and the
longer palm tapping technique both extracted less than the undistributed method that is to
say the coffee made using these methods was ever so slightly weaker than the control now at first
glance that seems like the opposite of what should happen most people would naturally assume that a
longer extraction time would result in more being extracted from the coffee however when we use
these techniques the restricted flow seems to have limited the overall extraction from the coffee
another point to note here is that while the ocd didn't really change the extraction time the shots
made using this device also had a slightly lower tds than the undistributed grounds now this seems
like a little bit of an anomaly but it does line up with the previous research done by the team at
socratic coffee they also saw a consistently lower extraction yield when using the ocd while keeping
the other variables the same we'll link to their research in the description if you want to look
into this a little bit further while we don't know why the shots made with the ocd extracted less i
will point out that a lower tds is not necessarily a bad thing for flavor as not everything we
extract from coffee has a positive impact on the final result so while the chart seems to show that
these shots are worse taste is a far more complex thing than these numbers on their own would
indicate before we wrap up this section and try to pull some practical conclusions out of all of this
i'll make a quick note on consistency while we really didn't see a big difference between the
average extraction between distributed grounds and undistributed grounds the undistributed method
definitely had less consistency from shot to shot for that reason alone we would recommend using
some method of distributing the grounds rather than just leaving it all to chance it is also
worth noting that we used a high-end commercial espresso grinder the mythos one for these tests
this produces even and less clumpy grounds than those smaller domestic grinders so this may have
an impact on how well the undistributed grounds did perform in these tests so what do we do
with all of this information unlike our tests on tamping these results are just not so cut
and dry there is no obvious winner as much as we definitely would like to see one the conclusion we
came to is this specific distribution techniques do not actually make as much of a difference
as we think it matters more do you pick a technique and use it consistently in your workflow
if you're going to start from scratch we recommend using the simplest method which is that easy palm
tapping technique we recommend it because it's quick doesn't cost anything and it is hygienic as
possible because you don't need to interact with that coffee any more than necessary and with that
in mind here's the process we teach our students in our classes first we grind the coffee into the
basket directly settling it just a little before we pull the handle from the grinder to ensure we
keep our mess on that bench to a minimum you've got to keep your benches clean secondly we weigh
out in dose to ensure that the correct amount of coffee is being used with our desired recipe
third using our preferred quick and efficient method of distribution it is to use the heel
of our palm and strike gently against the side of the basket to settle and level the
coffee grind the fourth step is to tamp firmly and evenly compressing the grind and removing
any potential air pockets the fifth step is to wipe and swipe and keep the ridge of the basket
and those lugs clean and ensure that you have a good seal prior to the extraction finally lock
that beast up and enjoy the good brew what do you think did we get it wrong is distribution
really the holy grail of perfect espresso you know what to do let us know in the comments
next time we're going to take a look at the effect of pressure is nine bars really the ideal
brewing pressure to get those best results we'll definitely try to find some answers for you soon