One thing that doesn’t get much easier is dealing with the build up of unpleasant flavours in an espresso machine. There are no shortcuts, you just have to deal with it regularly and to be honest it annoys me a lot. That taste is so obvious, so distracting, so unpleasant, that it ruins a lot of otherwise well made espresso for me.

I was thinking about the build up of dirt inside the group head caused by the release of pressure after you stop a shot. To better explain we have the following photo:

Photo courtesy of Dan Kehn of Home Barista

In a La Marzocco like this the route the water takes is a little confusing. It goes out of the far side of the neck of the group, through a flowmeter, back underneath the group head to a valve. When this valve is closed no water can leave the boiler, and when it opens water is pushed through and heads back inside the group head into that little tube you can see and towards the group head, until it drops down into the screw and showerscreen and over the coffee. ¹ Other machines have a similar tube, of varying lengths, that run between the valve and dispersion mechanism above the coffee. (Not all LM’s have this long of a pathway outside the group – machines that don’t have flow meters and more modern models have eliminated this pretty much.)

Dirt builds up here because that last tube is a two way street. At the end of the shot the pressure shoots back up the tube until it gets to the stop valve. This prevents anything from getting back into your boiler, and this valve is a three way valve allow this pressure to exit through a drain tube, usually ending up in the drainbox under the drip tray – though some deposit straight into the drip tray in the E61 style.

The only machines that don’t have this problem are lever machines. Lever machines only release the pressure when the spring has finished expanding. This is why you can’t interrupt a lever machine shot without making a mess. (I believe the technical term is ‘portafilter sneeze’)

This tube is very hot. Any liquid in this tube will likely evaporate and leave behind whatever it had dissolved. At the end of the shot this can mean dissolved coffee gets dragged into this tube where it will quickly deposit and start to taste unpleasant. Some of that unpleasantness will be picked up when you next pull a shot and fresh water is heading down the tube towards coffee. The same unpleasantness builds up pretty quickly underneath the basket of a portafilter, and we know from sticking our noses in there how bad that would taste. ²

I was wondering if getting into the habit of flushing immediately after pulling a shot would dramatically reduce the build up of dirt in that particular area. As a flush builds up no pressure it would mean that water would only travel one way out of the group, and hopefully drag with it any coffee before it had the chance to dry out and deposit.

Some people would argue that you should leave the puck in for temperature stability. Even the WBC references this idea by no longer looking inside the portafilters at start up as you can leave pucks in as you wish. I don’t think temperature stability is a concern, but I do think dirt is. I’d rather lose a little temp at the start of the shot than have to deal with the residue of a puck sat in a machine for 10 minutes. I’m not sure I’ve ever seen any proof that having a puck in promotes thermal stability, and if it is out there then a link in the comments would be great!

Also – would using a rampdown in pump pressure tofinish the shot have a similar effect, as there would be little to no pressure to release back into the group?

1. If none of this makes any sense then leave a comment and I will try and find a better way to explain.
2. This build up is why I would use Cafiza on a domestic espresso machine every day, even if I had just pulled one shot.

Outside of fashion my own feelings about espresso have changed dramatically over my career. It was all I knew coffee brewing to be for the first couple of years, and then I fell in love with brewed coffee and espresso seemed so awkward, so difficult and often so unrewarding in comparison. I was probably a bit too negative about espresso – I vaguely remember the idea of writing an article where Chris Tacy would defend espresso, and I would be all about brewed coffee.

Considering Chris’ fairly recent post this might seem a little odd. That particular conversation has gone down one path and I want to talk about something else – which is how much I enjoy brewing espresso these days.

I was recently running a couple of workshops at the Caffe Culture tradeshow, and I realised that explaining my own evolution of emotional attachment to espresso could be a good structure to explain how I now think about brewing.

This all starts with walking offstage in Berne in 2006 in the WBC finals.  I was delighted to be up on stage, I had a lot of fun but I definitely remember the feeling of walking off stage and feeling that I had absolutely no idea how to brew espresso.  I knew I had great raw materials, well roasted, and some nice kit to brew on.  I had been unable to push and prod my espresso into tasting how I wanted it to – I simply didn’t have the knowledge to exact the change on the cup profile that I wanted.

Looking back – I was serving fairly high dosed, fairly light roasted, underextracted and strong espresso.  It was sour, and no matter how much I slowed down the shot I couldn’t get it to sweeten up the way it had in practice.   Maybe I will come back to why later….

Espresso was so dispiriting for so long.  We end up using words like art for brewing, which I think is probably wrong.  Brewing is execution of task.  It should require craft, but not art.

Let me put this another way:  If I walk into your shop and order an espresso – how confident (as a percentage) would you be that the next shot you pull and serve will represent you, your shop and your coffee properly?  Be honest….

For a long time I felt that my own number was probably around 40-50% on a good day.  Sometimes espresso sucked, and I didn’t know why.  After the WBC the stress bumped up a notch – if I was serving coffee somewhere people would walk up with expectations and I rarely felt confident that I met them.

This nature of espresso is why there has been so much bullshit, myth and voodoo around for so long.  We explain things by looking for trends rather than explanations.  A classic example of this would be our approach to coffee grinding an humidity/weather.  I would argue that the weather will affect your grind, mostly by affecting how busy you are.  This impacts how hot your grinder is running, resulting in a grind change.  I simply haven’t seen a change in grind happen quickly with a rapid change in moisture/humidity. (I could imagine a gradual change would make more sense.)

I don’t want to get into a humidity debate – just an example of causation vs correlation.  Another might be the advent of naked portafilters.  At the time people were suddenly raving that they produced espresso with more body, more intensity, more sweetness.  The explanation was simply that people were pulling shorter shots, that looked normal volume because of the additional crema, but doing it so fairly slowly – they were pulling reasonably extracted ristrettos, they’d changes the recipe rather than the absence of a portafilters bottom somehow impact the extraction that occurred inside the basket above.

I’m getting off topic – I want to come back to why I enjoy espresso more.  I enjoy it more because it I have a functional recipe that I can replicate accurately, and relatively easily.

No doubt Vince Fedele had a big impact on this – with both the Mojo and the also the VST baskets.  I’ve already seen some strange things written about them, and what they do, so perhaps it is worth explaining a bit more.

We brew espresso by controlling flow rate using the resistance of the coffee cake.  Traditionally we think of two variables to control that resistance:  grind and dose.  Using these we can control how long the contact time is for a fixed volume of solvent (water).  The combination of contact time and quantity of water basically decide how much we extract from the coffee.

We didn’t factor in a third factor into that resistance – the bottom of a portafilter basket.  We tend to think of their job as being about filtration rather than impacting contact time.  However, they ought to be treated as an additional constant of resistance.  Most baskets are built with the majority of end users in mind.  Most end users – and that is a very large majorirty – are dosing around 7g per shot of espresso/14g for a double.  With a relatively small dose you need to grind pretty fine to get your desired contact time which has the benefit of exposing an increased surface area which makes the coffee easier to extract.

Higher doses – 18g+ came about somewhat by accident.  They were a product of grinding to order and using a basket to measure a dose of  ground coffee by volume.  The increase in dose meant additional resistance.  The basket resistance, plus the higher dose resistance meant we had to grind coarser.  This coarser grind made the coffee a lot harder to extract.  We found we liked the texture and strength of a higher dose of coffee, and this trend went further with people pulling shorter and shorter shots.  This meant we had less and less water to use in our extraction.  End result = underextraction.  A byproduct of this was darker roasting to help balance out the sourness of the underextracted cup.

The VST baskets are great because they do a few things exceptionally well.  They have less resistance the larger they are.  This means that you can grind much finer than you otherwise could before.  This means you can extract more.  This is good news.

Secondly – the way they are manufactured means that they are extremely consistent – an exact number and size of uniform holes. This means that if you have a 3 group all the baskets will act exactly the same.  Plus they’re built to be much thicker so they’ll last a lot longer.  This is a bit of a simplified explanation but hopefully you’ve all read the article in Barista Magazine that Vince wrote because it was great.  (Best edition of the magazine ever too!)

I haven’t really explained why this means I like espresso more.  I should probably do that now.

If I take a great espresso machine, and a VST 21g basket, and I put 20g of coffee into it and in around 28s I produce around 32g (brewing at 94C) then I know with 90%+ confidence that it will taste how I want it to.  That is, to me at least, pretty exciting.  It also massively reduces the stress of espresso.  I know that it won’t be a perfect shot, but it will be very tasty and something I’d be happy to sell.

I’ll be honest – the above recipe is where I always start.  I won’t taste it till I get there – because I don’t want the first 2 or 3 espressos I drink each day to suck.  I’m all for tasting bad espresso for diagnostic learning, but I’m also all for actually enjoying the damn drink.

Based on what I taste I might make changes, adjusting how I extract based on the cup.  If things are a just a touch out of balance on the acidic front then I will likely do something pretty simply like use a little more brew water to up the extraction.  34-35g of liquid from that dose will still have great mouthfeel if you brew it properly.  Very rarely do I need to make that change.  I know what kind of extraction yield I have, and I know what I like.  I’m not going to be prescriptive in that – the point of analysing espresso extraction (for me) is to understand what I enjoy, how I can change things to get there and to define the boundaries of good coffee for the recipe I am trying to make.

I’m sure some people will be horrified by the simplicity of the brewing.  Shouldn’t I spend longer “dialling in”, fighting my flawed grinder (because they’re all flawed), and burning out my palette to emerge the battered hero of espresso brewing, victorious in my reasonably good espresso which I might then struggle to replicate with any great consistency?  It amused me to see that Schomer (from his last blog post)¹ seems to revel in the challenge, in the difficulty, and sees it as being an important aspect to treating coffee brewing as a craft.  I don’t agree, but it is ok if you don’t agree with me (or with him).

I’ll be honest – I think weighing scales are an essential part of a good, streamlined, efficient dialling in routine in the morning.  I think they’re a great quick QC tool when you’ve got a tired tongue.  I think they’re a great training tool.  Volume measurement being so common and so flawed is one reason that I struggled with espresso for so long.  I think it is a very good reason that many other people struggle with it.  I think it is crazy not to spend £10 on a little tool that can do so much good. Do we really want to keep struggling with it to preserve our own egotistical version of our craft – or do we simply want to sell people delicious cups of coffee? If we can get past the basic challenge of consistent execution then perhaps we can get to a place where we can be much more creative with coffee.

I’m not saying that I can now brew perfect espresso every time.  That would be as idiotic as using the word perfect to begin with.  I find brewing espresso much easier than ever before, and I drink more espresso that I enjoy than ever before.  There are still many challenges with it, and a lot of things we don’t understand.  There are other factors impacting cup quality in ways that are hard to quantify – can’t help but constantly come back to grinders here too.

I promised a while back that I’d stop going on about weighing espresso.  I’m not going to apologise for breaking the promise, and I hope other people identify with my own to and fro with espresso.  It is still a completely frustrating thing in many other ways – if you listen to the last podcast with Tim Wendelboe then we both talk a little about this.

1. There is so much in that article that I’d like to respond to, but I don’t really want to get into an online blog tit-for-tat blog tennis match

Looking at the photo is seems almost ridiculous. They have a great equipment setup there, and it cost a lot less than even a cheap 2 group. It also takes up a lot less space. They offer different, contrasting coffees. The staff are passionate and informed about the product. ¹ They consistently serve really, really tasty coffee. People like really, really tasty coffee.

This doesn’t mean it has been easy. People still come to restaurants expecting to end a meal with an espresso. I think it takes some bravery for a restaurant to admit that espresso is incredibly difficult to do, and instead choose to do something of which they can be proud every time it is served. Inevitably success here comes down to service more than it does product, and I was really impressed by how thought out their approach was.

This isn’t new globally – but it is new to London. There are restaurants out there that are willing to invest in staff, equipment and training. There are many more restaurants knowingly serving an item on their menu that isn’t very good. In fact they know it is pretty bad. Many are too scared to make the change – I hope Trinity pave the way for others to follow. As a consumer and as a coffee professional I’d love to see more great coffee coming out of restaurants.

1. Doing staff training here is so much fun. We brew coffee, talk about it, argue preference and I answer lots of questions. I love it! That and the technical side of the training is easy to do, and the staff remember everything and just do a good job. The same is sadly not true of espresso training.

At this altitude water will boil at 91.2°C/196.2°F – below the 93.5°C/200°F that the Aurelias will be set to. What follows is mostly personal opinion¹, coupled with a possible experiment that might answer some questions.

When we’re brewing espresso the system is under pressure (9 bars mostly), rather than the much lower atmospheric pressure. One of the unique aspects of brewing under pressure is that water is able to dissolve a lot more CO2 than it usually can at atmospheric pressure. When the coffee liquid leaves the basket we see that it is unable to retain that CO2 which forms bubbles that get trapped by various surfactants as a foam: crema.

People will often remark that at altitude the coffee acts like it hasn’t had a chance to rest/degas. The espresso tends to have very large bubbles, and lacks strength – often disappearing very quickly. This is, of course, similar to brewing very fresh coffee (up to 48-96hrs post roast) at sea level.

What doesn’t make sense to me is that surely CO2 would be more likely to be drawn from the coffee bean when stored at low pressure than at higher pressure?

My guess (and it is a guess) is that the pressure change from the bottom of the basket to atmosphere is much larger than normal when brewing at altitude. I would guess that the saturation point for CO2 in water at 2625m is significantly lower than the saturation point at sea level. The liquid loses more gas, and we see this as bigger bubbles. With foams in liquid the strength is dependent on bubble size (the smaller the stronger – think good milk foam), so these larger bubbles of crema will disappear faster.

What does this mean for competitors? Here is my advice:

Bring scales. I know a lot of people don’t like it (though I don’t really understand why), but your espresso volume is going to be radically different for an identical flow rate at sea level. Know your brew recipe before you come, and before you start freaking out about how things taste, check whether you are brewing on spec. Espresso is a recipe that is based on weights and flow rates. Going by eye is tough. I’ve tried, when I was there in 2007, and it took a while before things made sense!

Another question remains – should espresso be aged longer for brewing at altitude?

This is a good question, and one I think we need to do a few experiments on. Ageing espresso will certainly reduce the amount of CO2 left in the coffee beans, but surely at the expense of some loss of pleasing aromas and the potential development of negative flavours. I’d like to run a two way experiment, but it needs participants who have access to coffee machines at different altitudes.

Take two bags of espresso from the same roasts/blending batch. Store one at sea level, store the other at high altitude. Ideally in similar temperatures. After 10 days bring both back down to sea level and observe variations in volume for a fixed weight of coffee, liquid and brew time. Based on my amateur theorising above – there should be no detectable differences, or – if anything – the coffee stored at altitude might have less crema/volume when brewed.

Then take two bags of identical espresso and store both for 10 days at sea level. Then brew one at sea level and one at altitude. Record variations in volume for fixed weight of coffee, liquid and brew time.

This way we’ll know whether the issue is ageing of brewing. I would predict that when brewed identically the high altitude espresso should be just as delicious as the low altitude one – but I am very happy to be proven wrong.

One aspect to consider is when the brewing liquid might reach boiling point. If someone is pulling very fast shots, where the brew water doesn’t lose much heat to the coffee – then I’d expect to see some issues towards the end of the shot as the exit liquid from the basket will be very close to boiling, if not boiling at high altitude. Properly brewed espressos shouldn’t (in theory) see the same problem. Anyone have video of a naked portafilter at high altitude?

Comments, thoughts, accurate science and brutal critiques of the above welcome!  Thanks to Brent Fortune for setting my brain off!

1. Warning: Amateur Science Alert!

This is quite frustrating – he’s raising an interesting point, but has done so in a way that allows it to be torn apart due to his presentation. You could say he’s unable to back it up, he’s making such sweeping statements topped up with a self confidence easily labelled as arrogance. ¹

My experience with pressure profiling is also fairly limited. Back in August ’08 I had a rather wonderful custom built profiler leant to me for a while, incredibly generously I should add, by John Ermacoff (who – despite not being a coffee industry person – has one of the most interesitng flickr accounts ever!).

People who knew about my experiments with that profiler have often asked why I haven’t really posted much about it online. In fact there is very little posted anywhere about pressure profiling, apart from many people being excited about its possibilities and about how various manufacturers are bringing machines to market to fulfill people’s interest.

Tim Wendelboe’s post has probably been my favourite on it, as I identified with a lot of what he said. If you haven’t read it then I’d suggest going there now.

My own experience’s with profiling could easily be summed up with a sentence stolen from that particular post:

It is also very easy to make really bad tasting shots.

Pressure profiling is immensely frustrating. You change a profile and you change the flavour, there is no denying the impact of changing pressure during the shot on the taste in the cup. Please note that this doesn’t mean the cup is improved, only different to before. Most of the time it is worse. What starts to break your head is wondering if it is worse because the profile is wrong, or because you got the dose/grind/brew weight wrong for that particular profile. Extraction analysis would help a little bit, but you’ll get lost incredibly fast.

Dialling in with tasting is also very difficult. Shot variance is often confusing when it comes to trying to diagnose problems via acidity/astringency/body/bitterness/balance/etc, and espresso palate fatigue was a major issue for me. I’d just start to feel like I was making some headway when I would hit the tasting wall.

What is worth noting is that despite the number of machines out there that can now profile to some extent, we still lack a coherence on even the basics of creating a profile for a certain coffee. I’d be willing to guess that most baristas using them are having a similar experience to me. I’d also hazard a guess that those using them in commercial environments (rather than lab/roastery/training room ones) are using very, very simple profiles so that they stand a chance of dialling in and repeating.

La Marzocco Profiling Chart: Interesting to note that the suggested profiles make no correlation with flavour, only suggestions to make notes on flavour - something you could say about varying dose or brew time.

Does this mean I think we should write off pressure profiling? Should it be dismissed in a Schomer-esque sweeping statement?

No. I think there is, somewhere in it, some mileage and benefit. However, to get at it will require a bit of cohesive work from the industry. A little crowdsourcing would be very useful here. I don’t know where would be a good hub, or what format that should be (forum/messageboard etc).

All of this is a long rambling answer to a barely asked question earlier in the post: Why didn’t I post anything about pressure profiling and my experiences with it?

I’ll be honest and admit that having near infinite control over the profile (which John’s machine offered, along with automation too) left me confused and intimidated. I hope that I’ve learned a little about espresso in the last two years (I certainly feel like I have), and I hope that I could now come back to it with a little more structure and forethought when it comes to experiments. However – at the time I felt I had nothing to say. I had found no repeatable trends, I had no theories, I’d played with a bunch of other people’s profiles (Andy Schecter and Greg Scace have both done way more work on this than me – and I was grateful for their input). I am curious whether other people out there are having a similar experience?

If we don’t make some headway, as a group, then we’ll probably end up abandoning it – too much work, too hard to replicate, too difficult to implement into a busy bar – and we might have missed something potentially very useful. So I will end this with a plea to those who are experimenting to share more – even if all they are sharing is a feeling of confusion and frustration – as all stand to benefit from a little shared experience.

1. What actually annoys me more is the pseudo science is his writing. ” the preservation of these unstable molecular structures that constitute coffee flavor/aroma” being an example. Ah yes – these unnamed, mystery structures of wonder, so unstable that they’ve somehow survived temperatures in excess of 400F during roasting, but still so unstable that 1F variance in water temp ruins all!  I should also add that in person he’s been nothing but friendly to me, so I feel a little mean writing this.

Ok, so that probably isn’t what you are thinking, but it was clearly what Paul from Coffee Hit was thinking. Two of these baskets arrived in the post this morning for me to play with, and play we did!

I’m a fan of teflon in some places.  I like my teflon coated portafilters very much, and I like my teflon coated low flow steam tip too.  These I was a little more skeptical about.  I made a very quick, silly little film to try and document a few things:

- The cone at the bottom never really forms on a naked portafilter.  I’m not sure why.  At first I thought it was because some holes must have gotten closed by the process, but the random nature of the patterns you get underneath seem to dispel that theory.

- Channelling is even easier than before.  (No surprises)

- Cleaning is, er, very easy! (No surprises there either!)

- The shots taste odd.  Odd in a way I can’t quite describe.

I’ll keep playing and report in if I find anything noteworthy! Enjoy the film!

This morning I was chatting to Jess as we were pulling shots (for in house consumption I should add).  The coffee wasn’t tasting great and we started talking about dialling in  and what we would change.  I like having a timer around for dialling in, aware that I am woefully inconsistent when it comes to mental timekeeping and it is a key variable in dialling in – brew time has been something I’ve been trained to focus on.  Couldn’t find the timer, so instead we grabbed the scales.

I know that I like our espresso blend when it is pulled at a brew ratio of around 65%.  This means that the weight of the ground coffee used is 65% of the weight of the brewed espresso liquid.  Our 20g dose would therefre yield a little under 31g of espresso.

What we did was keep the brewed mass as a fixed variable, ignore time and go by taste.  This proved surprisingly quick – the first shot was overextracted, so we nudged the grind a little coarser.  Second shot was better, but again the rough finish indicated overextraction.  One more nudge coarser and then sudden deliciousness.  One of the best espressos I’ve had in a long time – juicy, sweet, balanced, tonnes of clarity.¹ Out of curiousity I tracked down a timer and timed the next shot – 29 seconds…

It has been a while since I’ve done this exercise – it was interesting to choose a desired strength (which is essentially what a brew ratio does – assuming you are going to consistently extract the coffee properly).  Ignoring time and just using taste was oddly liberating.  I think that it also feels weird to think of that end mass as being fixed as the industry tends to defer (incorrectly in many ways) to the look of the pour.  ”Blonding” has long been problematic for me.  Aside from the massive potential for subjectivity (which isn’t hugely useful when it comes to communicating), blonding is the result of the flow containing less solubles than before – but offers no clue as to the quality and flavour of those solubles.

I posted this because this little exercise felt worthwhile, and I’d recommend other people try it.  I think around 65% as a brew ratio is a great place to start – enough liquid that you stand a chance of properly extracting the coffee, but still tonnes of texture and mouthfeel.  I’m not saying all espresso should be about 12% strength (what 65% as a brew ratio works out to in a proper extraction) – strength should always remain an individual preference I think.

On a side note – a quick tip:  some days on bar the coffee tastes great.  When it is tasting exactly how you like it then grab a weight measurement of dose and brew liquid.  When your coffee doesn’t taste so great – and that will happen – check your numbers and, 9 times out of 10, working back towards the tasty numbers will quickly improve your shots.

1. I should add that while we didn’t use the Mojo, I have no doubt that the extraction was around 19% – mostly due to the correlation between shots I’ve enjoyed in the past, and their readings

So – how many coffees? In January I drank 126 cups, so on average a daily consumption of 4.¹

Below is a quick breakdown of my consumption, as well as an explanation of what was logged, and what wasn’t.

What counts as a cup?  With brewed coffee this is usually a 6-8oz cup.  With cappuccinos they were usually single shot, 5oz drinks.  Flat whites² were double shots.

I didn’t log any coffee I drank as part of a training or when tasting to dial in a grind setting.  I didn’t include coffees I cupped, or brewed little tasters off rather than drank a cup of.  These were coffees I drank all of because I wanted coffee.

Daily consumption:

You can sort of see the dip at weekends here, though Sundays can often turn into very caffeinated days as I live so close to so much good coffee!  The 27th was the record day with 8 cups.

Let’s break down the total consumption into individual drinks.  I probably should have logged any brewed coffee as just “brewed” rather than the farm, but for various reasons I didn’t.  All espressos, regardless of blend, are logged as a group.

So – I drank a lot of espresso.  In fact, despite how much I moan about it, 51.6% of the coffees I drink are espresso.  Which seems quite high, but probably not unusual in the coffee community.

I’m actually a little disappointed in myself that brewed coffee only made up about 22% of my coffee consumption.

Here are a quick breakdown of my espresso based drinks and brewed coffees:

I hope I can keep tracking it for the rest of the year – though it is easy to forget.  Thankfully it is easy to post to daytum from my phone, or via twitter as well as through the web interface.  I am recording enough data so I can then break down my consumption into different countries throughout the year and other stuff, which might be interesting.

I guess this probably seems quite low – as daily consumption goes – but I found it interesting nonetheless!  If anyone has any questions then do let me know!

1. Well, 4.06 on average, but 4 is neater I suppose!
2. sick as those of us in the UK may be of them

At the London Gastronomy Seminars I was given a Mypressi Twist to play with by the UK distributor.  I had been toying with buying one having seen the hype online, so this was a rather pleasant surprise.

I didn’t really get a chance to play with it til yesterday afternoon.  I’ve played with it some more today and this is just a quick summary of my thoughts and what I think is particularly interesting about it.

First off – it makes pretty good espresso.  I know I am hardly the first person to make this observation, but I think everyone who tries it is pleasantly surprised.  I think with a few adjustments to technique then you can get something better than any espresso machine in its price bracket, or up to two or three times its price.  If you like milk drinks though – then this may not appeal to you.

I pulled a couple of shots yesterday, and for shot number three my curiousity kicked in.  What I think is most exciting about this is its potential for experimenting with extraction.  We can only really (safely) use water in an espresso machine.  My first thought was to reach for some whisky.  I probably should have heated it up first, as it was not delicious cold – though the shot did still look pretty good.  I then attempted a little macchiato using milk to brew the coffee.¹.  In hindsight I should probably have used skimmed milk, as the full fat seemed to clog the extraction and the result was (simply put) not good.  But there was potential!

This makes me quite excited about its possible use in barista competitions.  In the past it has been completely illegal to put anything other than coffee in the portafilter (for good reason!) but this would let you infuse anything you like.  You’ll still need to pull and use 4 shots from the competition espresso machine but the applications within signature drinks are almost endless.

You could brew espresso starting with brewed coffee.  You could use espresso and push it through something else to extract flavour into it.  In fact, I am going to pause writing this post and check how many shots you can get in the water section of the twist…..

*time passes*

OK – so 4 shots of espresso fit pretty nicely into the top chamber.  And the espresso seems to pull in a fairly normal (if slightly slow way).  This is a double espresso, brewed using 4 espressos:

The taste?  Not so great, not as bad as I was expecting, but not so great.  The texture was unbelievable.  The point is that this is exciting!  I should add that points for creativity in competitions don’t come from using clever things, or having a wild idea – they come from using clever things, or wild ideas to create something tasty.  There are no points for novelty.

The more I think about it, the more possibilities there seem – non-coffee applications too.  Cocktail people would surely have a million more ideas than me.  I still wonder though – what about pushing vodka through a basket of lemon and lime zest?  What if you use CO2 instead of N20? What if? What if? What if?

I’ve gotten off topic! Back to using it to brew coffee:

I have what not many other people have – a 53mm Scace, back from my days at La Spaziale.  The Mypressi uses a 53mm basket.  It didn’t take a giant leap of thought to dig out my device and start testing the brew temperature.  I’d seen quite a lot of speculation online about it, and I can only post my limited experiments and findings.  Here is a short video:

Preheating the water chamber is incredibly important.  You could tell this was later on in my experiments from the starting temp of the scace probe, which may have influenced readings somewhat.  Without preheating the temp was hovering around 80C.  I am sure I could have heated the top chamber more and squeezed into the 90s.  Nonetheless I think it is a pretty respectable brew temperature.  I’d love to hear how people are getting max temp out of theirs.

I was also a little surprised that the dose and grind I had set on my Synesso seemed to work well.  Out of curiousity I pulled a double on each simultaneously – same dose, same grind setting, same brew time.  Here is the video, data on the shots afterwards:

Synesso shot:  18.5g coffee, 33.4g brew liquid.  Extraction percentage 18.6%

Mypressi shot: 18.5g coffee, 42g brew liquid.  Extraction percentage 18.9%

This is a single experiment, so it would be foolish to take too much from it.  One could speculate that with the temperature issues the Mypressi will struggle to extract coffee as quickly as a hotter profile on a machine.  The fact that it took almost 25% more liquid to get the extraction percentage to match (in the same time frame – with very different pressure profiles I might wager, sadly I only have a 53mm Scace 1.0 – not 2.0) would suggest that if you like shorter shots you may be better off dropping your dose and going finer, and if you want a heavier dose you may need to push a little more water through.

So far I’ve only spent a couple of days with it – but overall I’m quite impressed and looking forward to playing with it some more.  I’ll take more more readings with the ExtractMojo, see if the above experiment was repeatable.  Would love to hear people’s thoughts, suggestions and ideas!

1. Tim Styles should trademark the term MilkPressi Twist

Is it me or is everyone else a little surprised at the lack of discussion of pressure profiling?

Most of the interesting discussion, if not just about all of it, has been over at home barista where various people are building pressure profiling units for their one group machines.  Still much of that discussion remains more about how to build it, than about desirable profiles.

Pressure profiling is undoubtedly going to become more readily available.  Though the capacities of the Slayer, the Strada and Cimbali’s new machine are all different, they are all chasing the ability to manipulate pump pressure to improve espresso.  A lot of this desire comes from the profile of espresso produced by lever machines, which have a very different pressure profile compared to a pump driven machine.

Perhaps I shouldn’t be surprised, given my own experiences with pressure profiling.  I was asked, a little while back, about why I hadn’t posted anything about it and I thought I would take this opportunity to explain:

John Ermacoff very kindly leant me a pressure profiler that he had built for a while.  I am not going to go into exactly how it worked, but we hooked it up to one of the groups in my 2 group Synesso.  This meant that I could only use one group at a time because then I had a Cyncra, not a Hydra, so the changes in pressure would influence both groups if they were open.

The machine allowed for almost any profile, and included a manual and automatic mode.  I played with the manual mode for a while, but prefered the automatic mode because it was repeatable and allowed me to make specific adjustments.

The entire time I used it I felt lost.  Juggling dose, grind size, flow rate, volume of espresso and time is enough.  Suddenly introducing pressure variations meant that it was a lot harder to isolate the problem.  If the shot was underextracted then keeping the profile but changing one variable often resulted in chasing my own tale and very quickly burning out my palate.

Changing the pressure even slightly undoubtedly changed the cup.  The impact was always obvious, but rarely did I ever feel as if I had genuinely improved the cup.  By giving me so much control I ended up lost in a sea of variables from which I never really found my way out.

I confess that I didn’t approach this as clinically as I should have.  I didn’t record enough data and often ended up defaulting back to a very simple profile – which seems to be quite a popular one online:

• - A relatively lower pressure preinfusion period, lasting long enough to soak the cake (5-8s depending on dose).
• - A smooth, relatively quick rise to 9 bars over 2-3s.
• - A period of 9 bars lasting 7-10s
• - A declining pressure in the remaining section, from 9 bars down to 8 or perhaps lower.

This is by no means what I would claim to be the perfect profile.  It is one, however, that I could rationalise in my head.  The period of preinfusion at the start would increase the likelihood of an even extraction.  The period of declining pressure in the final third meant that we were extracting the nearly-spent coffee less aggressively, yet still adding volume to the shot – aiding balance, and reducing negative flavours.  Of course you could easily tear this theory to pieces – I just couldn’t find a better way to explain it.¹

One thing that surprised me was how a lever machine acts, as I had initially thought this profile would be quite close to it.  I was quite wrong – though my experiences comes from the use of a Victoria Arduino Adonis and a Scace 2.

In terms of pressure the lever allowed line pressure through when pulled down, as the machine has a heat exchanger for brew water.  Upon releasing the lever the pressure shot up to around 12 bars before almost immediately starting to drop down towards 0 in a fairly linear fashion.  I only found this out after I had returned the profiler, and I wish I could have tried it on the Synesso.  That way I could have dose two identical baskets had a better idea of the influence of temperature on our love affair with lever espresso.  The Scace 2 showed that initially the brew water was very stable – in the first 12-15 second after pulling the lever the temperature barely moved – maybe 0.2/0.3°C.  Then the water gradually began to decrease in temperature, losing 4 or 5°C by the end of the shot.  This makes sense.  When the lever is pulled water fills the chamber above the coffee.  Only once it starts to pass through the coffee, and lose thermal mass, dose it really start to cool off.²

This profile is a very long way away from what most pressure profiling machines out there are doing – or at least what people have said they are doing.  Then again, as I said at the start, I can’t find many people talking much about it.  I guess I had hoped to see more on places like coffeed, coffeegeek, twitter or on various blogs.  Personally I’d be as interested in finding out what isn’t working for people, as much as what is.  When I asked the Cimbali engineer which profiles he liked best, he was a little evasive – in fact very few people are willing to really get behind any one profile.  I know these may change coffee to coffee, but with enough data out there I hope we’ll eventually be able to make a pretty good educated guess, the way we can with things like temperature and dose, based on the density of a particular coffee/blend.

I do have great hopes for pressure profiling, but at the same time realistic ones.  I don’t expect pressure profiling to discover sweetness, or flavours that have previously remained undiscovered in coffees.  I hope they can improve the clarity and presentation of them and help reduce detracting tastes and flavours.  It won’t make average greens taste great, or bad roasts acceptable.

Right now it seems that engineering is, for once, way ahead of the barista.  The pressure profiling machines coming can do almost anything we want – we just need to work out what that is…

I will close this post by saying thank you again to John Ermacoff – I learned a great deal through his incredibly generosity, and can’t wait to see what he comes up with next.

1. If anyone has any info on the effect of pressure at that stage in the shot – on caffeine extraction, oil emulsion etc etc then I would love to see it!
2. Again, correct me if I am wrong here