It's Called Cold Brew

Posted by Matthew Patrick McLauchlan on

Cold brewAt this time of year, you may start noticing a few changes at your local café. As the temperature begins to increase, so too does the number of gleaming little brown glass bottles and intricate glass devices on display – which look as if they came straight out of Breaking Bad. Yep, it’s ice coffee time! There are two main ways of cold brewing coffee: cold drip, where the water is dripped slowly through the coffee and cold brew, where the coffee is immersed in water for the entire brewing time. This is similar to the difference between a drip brewer (V60/Kalitta) and an immersion brewer (plunger/Clever Coffee Dripper) but much colder and much slower.

You may be more familiar with cold drip which is a common sight in Australian cafés these days. However, cold brew (which has its historical roots in New Orleans) is definitely on the rise. The coolest thing about cold brew is that it doesn’t require any specialised equipment to make it. It can be made in a plunger or a jar, although best results might be achieved using something like the Toddy Cold Brew System, which also makes it easier to prepare in bulk. Here at the Academy, we’ve really been loving cold brew for the ease of preparation and the consistency of the results. A cold drip will require monitoring to ensure the drip rate stays steady, whilst a cold brew is quite happy just chillin’ in the fridge. One big thing you lose though is the visual appeal of the device itself. Most cold drippers look great and can really help sell the coffee, while most immersion brewers look a bit more ‘practical’. For a closer look at how to make cold drip coffee, check out this sweet video: Cold Drip Step by Step video by our head trainer, Andy Easthope. However for this article, we’ll be focusing entirely on cold brew.

Slow it down

The first thing to know about cold brew is that it takes a long time to make. This is because without heat, the extraction rate is radically reduced. You know how sugar is harder to dissolve in cold water? Well, it’s the same thing with all the flavour elements of coffee, but inside the beans. The cold brewing process will also change the nature of the extracted flavours. Generally you’re going to see a reduction in acidity and bitterness – although with the right coffee and technique, some remarkably fruity brews can be achieved. We will also miss out on all that astringency and bitterness which can come with cooling down hot coffee, particularly espresso, meaning this drink can be enjoyed black without having to add milk and ice cream!

Getting ready

Ok, we’re almost ready to go; we just need a few things.

  • A receptacle: This can be anything from a big, 20l Toddy for commercial prep to an old jam jar or an Aeropress. I’ve been making cold brew in my trusty old plunger for years.
  • A filter: You need something to separate the coffee and the brew. This might be a part of your brewing device, but if you’re going the jar route you’ll need to sort out a filter of some kind, like a pourover or some cheesecloth. A metal mesh filter (plunger) will give you more body, whilst paper or cloth will result in a cleaner cup.
  • Coffee: Cold brew needs something delicious and freshly roasted! I tend to use filter roasted coffee, and enjoy it black. If you’re planning on adding milk later, you may want to stick with espresso roast as the milk will tend to mute the more delicate flavours.
  • Water: We need good quality water for any coffee we're making. As a general rule, tap water sucks and a filter jug is a minimum requirement. See this article Experimenting With The Effect on Water Quality for deeper nerdery.
  • A grinder: Freshly ground coffee is the way to go. A Baratza is a great option for cold brew or, if you are keen on something cheaper, then a hand grinder is probably the best cost/benefit investment you can make in coffee. Full range of grinders . You can use pre-ground coffee if you really have to, it just won’t be as delicious.

Ok, let’s brew this thing

  • The ratio (black): For coffee we’ll be drinking black, 80g/l is the ratio we love. This is slightly higher than for hot-brewed coffee as it is more difficult to get the desired flavour strength from cold brew. This ratio results in a fresh, delicious brew that is strong enough to be enjoyed straight from the fridge. Of course you can (and should) play with this ratio to find something that suits both your personal taste and the coffee you’re working with. Once you’ve settled on your ratio, work out the size of your brewer and weigh out an appropriate amount of coffee.
  • The ratio (white): If you’re planning on adding milk to your brew, you’ll want to make a stronger concentrate, and use an espresso roast: 120g/l will taste good when diluted with around 1/3 milk. Once you’ve settled on your ratio, work out the size of your brewer and weigh out an appropriate amount of coffee.
  • The grind: We’ll be going fairly coarse, a bit coarser than a normal filter grind. Grind size is difficult to communicate in words, but it should feel like coarse sand.
  • The pour: Now get your coffee in that brewer and pour the water in. You’ll want to weigh the water if it’s a small amount, but at larger volumes a jug with volume markers should be accurate enough. All the coffee should be wet, so make sure you pour around in circles and don’t leave any clumps. If you fail to get it all wet, you can give the slurry a gentle stir; however, excess agitation will lead to bitterness in the brew. Any agitation at all will lead to an increase in extraction rate and for cold brew, the slower the better! If you want to stir your coffee, you could consider reducing the contact time.
  • The wait: Now we wait. I normally leave it overnight, for 12 hours at least. Then strain your coffee, seal it up and keep it in the fridge. If it’s properly sealed and stored in glass, it should keep for 1-2 weeks. Now enjoy your coffee, you’ve earned it! It really is the best way to wake up from a hot, sleepless night.

I’ve kept this guide intentionally open as this is such an easy, flexible brew method for cafés and home baristas alike. We had a lot of fun experimenting with grind, brew time, temperature, agitation and different coffees and I encourage you to do the same! However for clarity and ease of reference, I’ve included a simple, step-by-step recipe below.

Ingredients

  • 40g filter roasted coffee beans or 60g espresso roast
  • 500ml water
  • Plunger (or any receptacle that’s food safe and sealable)

Recipe

  1. Grind the coffee at a coarse grind setting and place it in the plunger
  2. Pour the water into the plunger, making sure to wet all the grounds
  3. Place the lid on the plunger and leave it in the fridge for 12 hours
  4. Plunge the coffee and decant it into a bottle or jar
  5. (optional) Pour the coffee through a paper filter to clean up the body
  6. Enjoy your coffee! Remember it can be stored (sealed and in the fridge) for 1-2 weeks.

This article was originally published on the Five Senses Coffee website: It’s called cold brew.

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The Truth about the Flat White

Posted by Matthew Patrick McLauchlan on

Flat WhiteFlat (no foam) and white (milk) — Aussies sure do like to keep it simple. The fact that this coffee is an absolute staple on any Australian/New Zealand café menu, as well as one of the most ordered coffees in our part of the world, makes it surprising that it hasn't really taken off anywhere else. I think I know why, but being a foreigner myself I thought it might be best to show some due diligence and do a bit of research. (Enter Google)

Was I surprised to not find many hardened 'facts' about the flat white on the internet? Not at all! And, in an era in which we rely so much on Google to give us the 'all the facts', it's no wonder customers are easily confused. One titbit of info that was news to me was that a food historian gave Sydney coffee drinkers in the 1980's the credit for coming up with the term 'flat white.' He says it was as simple as the coffee being 'flat and white' in contrast to a 'long black' and a 'short black.' To that claim, I say that it sounds like a very logical Australian thing to do. End of naming story.

There were, of course, a couple sentences which started with statements such as, 'A true flat white ought to have...' There were also some claims that it 'should' be served in a 150ml-160ml cup. One internet writer even went as far as to say that it 'must' be served over a 'single or double ristretto' which kind of surprised me. Regardless of what I think to be true, the reality is that there is no 'original recipe' for a flat white. It started as a trend and doesn't fit perfectly into any box. (But isn't that what we all like about coffee?) However, it isn't all intangible and elusive; there are some 'realistic expectations' for customers when ordering a flat white. These expectations are based on current trends (i.e. what cafés are now serving) which then help define the drink. It really is no use saying, 'It should be served in a 150ml cup' if that means that 90% of cafés are serving it in the 'wrong' way.

The neat thing about trends is that they are always changing — and I actually think we are on the cusp of another shift. The truth is that speciality coffee people start most of the café trends which have anything to do with amplifying and differentiating the coffee experience. They push the boundaries and take the time to educate their customers (for which they are often criticised) but in the end, because their ideas are sound and based on taste, eventually other cafés follow suit — all the way down the chain. And when finally the whole industry is on board, it's time for another change: enter the next trend here.

Here is where I think the flat white is now, and where it is going in the future.

Name: That's easy! It's not changing and it's probably the only thing you can be certain of.

Flavour expectation: It's currently one of the milkiest drinks on the menu, equal to or slightly stronger than a latte. I do think this will change in the future. I predict that speciality cafés will slowly ditch the latte glass and replace it with a similar or slightly larger bowl, more like the American-style latte. This would mean that we may also see flat whites really live up to their 'wiki definition' of being different to lattes by being served in a 150ml cup. Then they would become a stronger tasting drink. (Smaller cup = less milk = same coffee = more flavour.)

Cup Size: Let's be honest here — the average flat white (I would like to highlight the word 'average' here) is served in a 180ml-210ml wide-brimmed bowl. It's a milky drink and very much a replica of the rest of the world's lattes, hence why I think it hasn't really taken off anywhere else. It's a bona-fide 'double-up'! As I mentioned above, as lattes move to cups, flat whites may move to smaller cups. Let's wait and see, hey?

Coffee: This is a tricky one as there are now so many different styles of coffee service. One shot is not necessary equal in value from café to café, not to mention the fact that some use a double shot and some use a single as a standard base. Is it a short and tight pour (ristretto), longer and faster pour (espresso) or somewhere in between (add in your own ideas)? The style of shot, combined with the style of coffee and the style of roast, means there is potential for a wide range of results. I guess this is where your own subjectivity comes in. Cafés create what they think is best, and you buy what you think is best. They will never get it 100% right, but nor will you, so don't expect every single coffee experience to wow you. Take some time to find the local café that suits you best.

Milk: We always say 'no foam' but it's actually better described as a thin layer of foam. Just enough to give it a slightly creamy texture when you bring it to your lips, but not enough to feel like a babychino! An easy visual cue of good FW milk is when the top layer is glossy, with a nice layer of wet foam consisting of tight bubbles which you can barely see immediately after it's poured.

Temperature: Same as for all your other coffees, the temperature should be 70 degrees Celsius max. Not scalding hot! If you want to burn your lips, order a long black and skull it the moment it hits your table. I mean, I just don't understand the milk burning argument. I just get these vague memories of burnt milk and oatmeal as a kid and I can't relate to people wanting that flavour. I know it's a sore spot for some, but that's my two cents worth and I'm sticking to it.

In summary, you can expect a single/double shot ristretto/espresso base in a ceramic cup anywhere from 150ml-220ml, with a thin layer of foam (if your barista is good) and, potentially, a pretty piece of latte art on the top at a very reasonable 65 - 70 degrees Celsius.

So you'd better think twice before you throw your hands up in horror, and understand that there are no RULES. Just enjoy it!

This article was originally published on the Five Senses Coffee website: The Truth about the Flat White.

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The Espresso Menu Explained

Posted by Matthew Patrick McLauchlan on

© Image provided with permission by Matt O'Donohue from Abstract Gourmet. All rights reserved by photographer

It is easy to forget, for a native speaker, that the lingo of coffee can be complex and confusing. Try explaining to a freshly arrived tourist that they can’t just order “a coffee”, before leading them through the Byzantine laws and sub-clauses of the modern coffee menu, if you need to be reminded. Furthermore, each café is free to make their own decisions about what these different coffee words mean, and the common definitions shift over time and from place to place. In this article I won’t be diving into the history of these drinks, or attempting to explain how we got where we are now. Instead, I’ll aim to provide a practical guide to the state of the specialty menu as it is now, and what it might look like in the future.

Black Coffees

Espresso/Short Black
The simplest drink to prepare, an espresso is a single shot of coffee, usually served in a small demitasse cup. The term short black is used interchangeably with espresso, although I have heard of people adding extra hot water when a short black is ordered. Recently, cafes have started to experiment with the cups the espresso is served in. An espresso served in a wider cup or glass allows more aroma to reach the drinker, whilst serving the espresso in a room-temperature, or even chilled, cup will drop the temperature of the coffee faster and create a different sensory experience.

Long Black/Americano
The long black is usually a double espresso, poured over hot water. The espresso is traditionally poured directly on to the water, although this is primarily for aesthetic reasons (to keep the crema intact,) and you could make an argument that it tastes better all mixed in. The ratio of coffee to water varies, but I think somewhere in the 1:1 to 1:2 range tastes delicious. It is really important to get the temperature of the water right. Just like your milk coffees, long blacks should be at a drinkable temperature when first prepared, I don’t want to burn my tongue anymore!


© Image provided with permission by Emily Bartlett. All rights reserved by photographer

Milk Coffees

Flat Whites/Lattes/Cappuccinos
Let’s get this out of the way: they’re basically all the same. While that might hurt to hear, it’s the truth. We’ll talk about why soon, but first let’s look at the “differences.” flat whites, lattes and capps are generally comprised of a single shot of espresso, topped up with steamed milk, served in a cup 150ml-200ml in size, although your mileage may vary. In most cases, lattes will be served in a slightly larger glass, while the capp and flat white are in the same ceramic cup. The cappuccino (usually) gets a dusting of chocolate powder too. The last difference is in the foam level, with the flat white sitting at around 1/2cm of foam, the latte at 1cm and the capp at 1.5cm, but again, this will vary wildly between cafes and baristas.

So, all three of these drinks boil down to espresso mixed with about the same amount of milk. Granted, the amount of foam will affect both the textural experience and strength of the drink (more foam equals less milk equals more strength.)The difference is often minimal, however and anyway, is there a “best” amount of foam? What amount of foam is the most delicious? I want that one.

Macchiato
You’ve probably heard that Macchiato means “stained” in Italian, and this is true. At its simplest, a macchiato is a single espresso with a small amount of milk and a “stain” or “spot” of foam on top of the coffee. Of course, it’s not really so simple, there are actually many variations on this drink, which seems to fluctuate wildly according to location. Some common varieties are the “short macc topped up,” which is a single espresso in a demitasse topped up with milk; the “long macc traditional,” which is a double espresso in a latte glass with a dash of milk and foam; and the “long macc topped up,” which is the same drink, topped up.

Piccolo Latte
Piccolos are lattes made with less milk. They’re either identical to a short macc topped up, or in their own, slightly larger than an espresso cup but smaller than a latte glass, cup.

Babycinos
A babyccino order can be an irritation to many baristas, however a perfectly made babyccino can be a thing of beauty, and bring a lot of joy to our smallest customers. The babycino should be almost entirely foam because babies get enough milk in their day to day. The foam should be dense and at a cool temperature, with a light dusting of chocolate. Syrup in the bottom is cheating and can lead to sugar-related meltdowns later in the day.

The Future

The problem with modern menus is that they provide lots of drink options, with little in the way of meaningful choice. Drinks that may have been historically different (big, milky lattes; cappuccinos with mountains of foam; small, dense flat whites) have been homogenised into drinks that are more delicious, but fundamentally the same. I believe the coffee menu should be designed actively, not just by serving what everyone else serves, but with a focus on engaging your customers’ minds and palates. One approach is to pare the menu back to the basics, and offer a minimum of drinks that are all delicious and show your coffee at its best, for example just offering black and white coffee instead of an endless list. Although this is not a new idea, it’s one that hasn’t caught on as big as it could have. Another approach is to add drinks that are meaningfully different. Adding signature-drink/cocktail-type concoctions to the menu is something people are already playing with, and it’s a fun way to experiment with new flavour experiences. We’re already offering different coffees, could we extend this to offering different espresso styles on the same menu? And while I’m asking for stuff, can we get more espresso tonics please? They’re delicious.

The counter-argument to all this is that customers like having this arbitrary choice, that they enjoy the ritual of their morning cup of coffee and will be upset if some upstart barista tries to get in their way. People tend to project their personality onto their favourite drink and derive satisfaction from that. In fact, drink choices can help to define a person’s personality, both internally and externally. Maybe they like being a serious “long macc drinker,” or a happy-go-lucky “latte lover.” And that tradition is truly valuable and not something to be thrown away lightly. Not every café needs to be challenging the status quo, but every café owner should be thinking about it, and considering how they’d like to present their product. Change has to be made with a light touch, and excellent service is the only way to smooth out the bumps in the road. We can create new traditions, perhaps more meaningful ones, or maybe we’re ok with the old ones?

This article was originally published on the Five Senses Coffee website: The espresso menu explained.

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Espresso Shot Troubleshooting

Posted by Matthew Patrick McLauchlan on

Espresso shot troubleshooting

It doesn’t take much for a day to turn from smooth to turbulent when you’re working in a café. I guess it is just part of the rollercoaster ride that defines the hospitality lifestyle! one of the things that can start the slippery slope towards anxiety is a coffee pour that just doesn’t add up — or a question posed by a customer that you just can’t explain.

Here we’ll take a look at some typical espresso-related problems that can be easily solved by a bit of basic troubleshooting.

THIN ESPRESSO

  • First check the roast date of your coffee. If your coffee was roasted more than three weeks ago, it will lack viscosity.
  • Next examine your shot speed. If the shot is pouring too slowly, it will appear thin and oily. Remember, a coarser grind equates to a faster shot, and a finer grind is slower.
  • How’s your volume? Remember that the end of the espresso is signified by the third colour change. If your shot is running past the end of the second change, you may need to adjust your volumetric settings.
  • You may also need to check the temperature and pressure of your machine. This is easy to do on more modern machines. Generally the temperature will sit between 92C - 96C. Then there are the two pressure settings on your machine. One is the steam pressure which should sit between 1 - 1.5 bars and the other is the pump pressure which should be nine bars while it is pumping. (Don?t read it while the machine is idle, as you will only be reading the line pressure.)

CREMA

BUBBLY / QUICK DISSIPATION

  • First take note of your coffee’s roast date. When coffee is roasted it produces carbon dioxide as a byproduct of the roasting process. If the roasted coffee is too fresh, you will experience a lot of bubbles or quick dissipation. Allow the beans a couple of days to settle and degas in order to obtain a more stable crema, however, keep in mind that coffee will go stale 21 days past the roast date. In addition, the longer you allow your coffee to de-gas, the more the flavour will be changed as well.

NO CREMA ON A LONG BLACK

  • This can also be associated with quick dissipation, where the crema disappears quickly — see ‘Quick Dissipation’ above.
  • If there is absolutely no crema, this can be caused by stale coffee. Again, check to make sure your coffee is within three weeks of its roast date.
  • Evaluate how you are storing your coffee. Remember, it needs to be in a cool, dry place — not in excessive heat or in the refrigerator. Both of these will cause the immediate decay of your coffee.
  • If you have a Synesso or Expobar, check that the brew temperature is correct. On the Synesso, it is easy to accidently switch off the black element breaker when cleaning underneath the machine, so make sure it is switched to the left.
  • This is a bit of a weird one — but make sure you don’t have any detergent residue on your cups!

SHOT CHANNELLING

  • Remember, the idea of an espresso coffee machine is for water to flow at proper pressure though a given amount of coffee. Shot channelling is when the water doesn’t have an even press through the coffee puck — it either goes around the coffee or through an easy path within the coffee puck.
  • To evaluate the evenness of your extraction, the best tool is the Naked Portafilter, which enables you to analyse the flow of water through the coffee puck. (For more information on this, check out the Naked Portafilter story I wrote a while back.)
  • Make sure you have the correct amount of coffee in the basket for your machine – the puck should be firm with a spongy surface.
  • Ensure that the basket is not wet. Because the water coming from your machine will follow any damp path, a wet basket will encourage all of the water to go around the puck rather than through it.
  • Your tamp needs to be level. Otherwise, all of the water will take the path of least resistance, which is through the thinnest part of your puck.
  • Don’t tap on the side of your portafilter. Tapping on the side just makes your puck look pretty, it doesn’t make the coffee taste better. What you are risking is either breaking the seal of coffee with the edge of the basket or forming a crack through the centre of the puck, both of which will result in an uneven extraction.

EARLY BLONDING

  • If your coffee blonds too early, you risk reducing the body and sweetness of your coffee, resulting in a bitter or ashy flavour.
  • Stale coffee will also blonde early. Check your roast date and storage.
  • Examine the speed of your pour. If your shot is too fast, the coffee will blonde sooner.
  • Evaluate whether your shot is channelling — see ‘Channelling’ above.
  • Check your machine temperature.

HARSH OR BITTER

  • Make sure that your coffee is within three weeks of the roast date and that it has been stored correctly.
  • Remember that the shot speed and the colour change of your coffee must always be accurate. A shot that is too slow or pulled too long will cause the coffee to turn bitter.
  • Check that the temperature of your machine hasn’t changed.

SOURNESS

  • This can be caused by coffee that is a little too fresh. Try aging your coffee for a couple of extra days (never longer than three weeks though) to stabilise your coffee.
  • Check your shot speed — a fast shot can cause sourness.
  • Make sure your temperatures are set correctly.

As you can see, most of these problems can be easily avoided with fresh coffee, proper storage, and adequate technique. The use of a temperature stable, multi-boiler machine is also important, for a single boiler heat exchange machine will naturally fluctuate in temperature and result in an inconsistent flavour. Multi-boiler machines are more stable and consistent with the water temperature they deliver.

If all else fails, give us (or your local technician) a call. When the problem goes beyond general troubleshooting, your technician will be able to make a more detailed assessment of things such as your pressure gauge and grinder burrs. It’s all in the pursuit of great coffee.

This article was originally published on the Five Senses Coffee website: Espresso Shot Troubleshooting.

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Does the VST Basket Live up to the Hype?

Posted by Matthew Patrick McLauchlan on

 VST

VST baskets are not a new piece of equipment by any means. Since their release around 2-3 years ago, many cafés and home espresso enthusiasts have been sold on the idea of a precision-engineered, optimised filter basket and have switched their standard, machine-included baskets for shiny new VSTs.

For a seemingly simple set of changes, VST baskets carry plenty of claims which seem to justify investing in them. They address the lack of quality and consistency in the filter-basket manufacturing process and they are designed as a filter basket with precise dimensions, standardised filter holes and a target dose mass for each basket.

In the time that I’ve been using them I’ve encountered mixed responses from those who have made the switch. Some users claim greater consistency and the ability to extract their shots in greater volumes without negative effects on flavour; other users have switched back to their old baskets, disappointed with their results and often citing inconsistency, shot-channelling, sloppy coffee-pucks and confusing extraction flow rates as good reasons to stop, cease and desist. Still others really can’t see any difference at all, and wonder why they’ve just spent over $90 replacing their three filter baskets.

So what’s the deal here? Are they better, or aren’t they? Do we really need them in order to get excellent results?

Well, the quick answer is no. The definition of what constitutes a great espresso is not universally agreed upon. That being said, the above questions and the ‘no’ conclusion might also be a little out of context when it comes to VST baskets.

As we have found, the real benefits of using VST baskets comes about when we start to measure, record and experiment with our brewing parameters and are thus able to assess what they can and cannot do for a coffee programme. So we set out to test VST baskets in terms of what sort of consistency they produce over a range of extractions, and whether they are as finicky and inconsistent to use as some have claimed.

Testing the VSTs Using Richard Muhl’s crazy shot brewing device and a Synesso Sabre in our Victorian Training facility, we set about testing just how consistent VST baskets are and found it was easy to obtain consistency and repeatability in our results by exercising due care and employing repeatable practices.

To put this in context, we need to define exactly what we are testing. Filter baskets act as the environment where it all takes place to produce the filtered, emulsified, diffused beverage we know as espresso coffee. VST baskets are designed with specificity in mind in terms of how much coffee mass we should be dosing, and have filter holes which are sized and distributed specifically to result in a particular extraction yield range of 18-22%, across a range of brew ratios when we adjust our grind particle size to match.

“Whuh?” you may exclaim!

Dose mass This is the amount of coffee we use, expressed as weight. VST baskets are designed to work within a 3 - 4 gram range of dose weights and are manufactured in several sizes. Most filter baskets are purposely or inadvertently designed with this attributed, but VSTs also have filter holes which match the target coffee mass and particle size to deliver specific results.

Brew ratio This is the amount of coffee mass that goes into the basket vs. the beverage mass that comes out. For example, a fairly standard espresso shot uses a 1 : 1 ratio. (This is considered to be a ristretto shot by VST standards.) Or you can think of it as 20 grams of coffee mass vs 20 grams of extracted beverage. Different brew ratios will have different levels of concentration or strength.

Yield % This is the total amount of diffused elements obtained from coffee during extraction. Put simply, it is the maximum amount of a coffee’s mass which is removable. It’s usually around 28%, but we don’t want all of that.

Generally with espresso, a reading of the Total Dissolved Solid % (the amount of solids present in our brew) is attained using refractometery. Using the initial dose mass, we can then calculate how much of our coffee’s diffusible content has been removed. Historically, a range of 18-22% of the coffee mass has been deemed to be the spot to hit in terms of flavour. The TDS % differs depending on how diluted the espresso is, and directly correlates to concentration or strength.

Filter holes Filter baskets have holes which allow brewed liquid to pass through them. The more total surface area these holes provide as an escape route for water, the faster our flow rate will become.

Think of it like this: if we have two filter baskets filled with equal amounts of coffee which are tamped in exactly the same way and one of the baskets has more holes than the other, then in that basket the water will have more chance of escaping during the extraction process, and the overall flow rate of our beverage (weight over time) will increase. If all other parameters are stable, then dose mass, distribution and grind size should be the only factors influencing the amount of beverage mass we achieve over time.

Or not? Judging by the feedback I’ve heard so far, results are up and down with VSTs. Thankfully, our testing on VSTs shows that stable brewing parameters are very easy to achieve using VSTs. In fact, after using them for a few weeks of training I am more than convinced that they are delivering more consistent results than our previous baskets, not to mention some amazing tasting shots.

In both VIC and WA, we found that keeping the parameters consistent was the key to ensuring they behave in the same way each time we extract. Furthermore, the way we initially dialled in our parameters (in terms of dose volume, mass and particle size) was critical to ensuring that they behaved in a stable fashion.

If the way we set these baskets up determines what sort of results we can attain, then it’s crucial we understand what we are looking to achieve.

Filter baskets are just a small part of making espresso coffee. So let’s look at some of the brew parameters which are directly affected by a filter basket. Let’s put things in context in an unashamedly complex fashion.

Dose mass, volume, headroom and saturation. Simply put, the dose is the mass of coffee we end up with in our portafilter for an extraction. This can be a fairly accurate and repeatable parameter if we weigh it while dialling in the grinder. Also, there are suitable and unsuitable doses for each individual filter basket, a concept which is based on the idea that the relationship between the following parameters is commonly linked:

Ground coffee volume vs. grind particle size The finer we grind coffee, the more efficiently it will fit together when compressed and the less space it will take up. Put another way, if we are measuring and setting the dose by weight, this means that when we adjust our grind finer, the level at which the coffee sits in the basket will drop even though the weight of coffee has not changed. Of course, it works in the opposite way if we are grinding coarser. We principally use the size of our grinds to affect the rate at which our espresso flows. However, the same extraction process is also affected by the depth at which coffee sits in a portafilter due to saturation and headroom (see below).

So why does this matter? Well, water behaves in interesting ways during the extraction process and those effects become fairly evident when we analyse the effects of headroom.

Headroom Headroom is the space above where the coffee sits level in the basket. Headroom ultimately dictates how much or little space coffee has to expand during the extraction process.

Coffee tends to expand considerably when it is extracting, and it needs a little space to do so without impacting or restricting the water flow. If we use too much coffee when dosing, then we limit the space that coffee can expand in, which conversely affects how evenly the saturation process (see ‘Saturation and Resistance’ below) can occur. If we use too little, we allow the coffee to expand to a point where water can easily bypass the grounds below, also affecting how evenly water flows throughout the extraction process.

This means that for every filter basket, there is a volume of coffee which will allow a homogenous saturation, and a matching grind setting which will provide us with extraction flow rates and yields that are most desirable. There is a tipping point when saturation becomes inconsistent, but it’s also worth noting that a range of dose volumes work well for a given basket.

Saturation and resistance Saturation and resistance are other factors which are affected by the dose mass, volume and grind. Within the extraction process, water generally travels around the edges of the basket and eventually makes its way through the centre of the shot as resistance is built up from extraction pressure and the coffee itself. The more depth we create from our dose volume, the more we exaggerate this effect; the less depth we create, the faster this process can occur.

The best way to use VSTs If you’ve been following the gist of this article so far, you can probably tell I’m in favour of VST baskets. My only advice would be to experiment when setting them up to get optimal results.

We’ve found that VST baskets produce impressive results in terms of repeatability, attainability and flavour, but it all comes back to our ability to adjust and refine in order to achieve these results. The variables involved in espresso can often outweigh the ease of practice: if a filter basket can help us attain specificity and repeatability, then using them makes our goal of producing amazing espresso easier to accomplish.

This article was originally published on the Five Senses Coffee website: Does the VST basket live up to the hype?.

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