The Curious Barista's Guide to Coffee
Page 18
Grind: Coarse
1
Pop a paper filter in the filter basket and rinse with hot water.
2
Turn the Aeropress upside-down and insert the plunger cylinder about 10 mm/⅓ inch down into the base cylinder so that the gasket is secure. (A)
3
Place the upside-down brewer on a set of digital scales, so that the water and coffee can be added to the brewing chamber.
4
Weigh and grind 16 g/½ oz coffee and drop it into the brew chamber. (B)
5
Reset your scales and pour in 240 g (240 ml/ 8 fl. oz) hot water and stir. (C) (D)
6
Allow to brew for 3 minutes, then briefly stir again and clip on the filter basket. (E)
7
Turn the Aeropress over and gently press all of the liquid out – this should take no more than 20 seconds – into a cup or carafe. (F) (G)
8
Allow to cool slightly (while you clean up) and enjoy. (H)
VACUUM OR SYPHON BREWING
The first known vacuum pot (also known as a syphon) dates back to a drawing of a coffee maker from 1827 created by Professor Norrenberg of Tubingen, Germany. Following on from this there were a handful of patents filed in both Germany and France in the 1830s, many of them submitted by women, culminating in Lyon resident Madame Vassieux’s design of 1841, which consisted of a double-globe assembly, with a spigot in the lower globe to dispense the coffee, and a decorative, pierced-metal crown at the top. Amazingly, modern vacuum pots are virtually indistinguishable from Vassieux’s 170-year-old design. But besides being an innovative new method for making coffee, it is also thought to be one of the first brewers made from glass, a trend that continued through the 19th century, as glass in general became more readily available in Europe.
HOW IT WORKS
Both vacuum pots and atmospheric pressure pots work across two vessels that can be connected horizontally or vertically by a pipe with some kind of filter arrangement (usually cloth) on the end. The first vessel is set above a heat source and water is added. The second vessel contains the ground coffee. As the water heats in the first vessel, the steam pressure increases and the water is forced through the pipe into the second vessel to mix with the coffee. Once the heat source is extinguished, the pressure in the first vessel drops and pulls the brewed coffee through, filtering out the grounds on the way. In an atmospheric pressure pot, there is a cap on the spout, which is removed, causing the system to pressurize and the brewed coffee to filter through to the lower vessel by gravity alone.
The important point to recognize with all these brewing methods is that the water does not boil. There is sufficient steam pressure created by the hot water to push it from one vessel to the next. In fact, it is nigh on impossible to make the water boil in these devices, since the system is pressurized and the laws of physics prevent it. This is a good thing.
One of the main differences between vacuum brewing and other brewing methods is the consistency of temperature. In a French press, the extraction drops in temperature over time, and in filter brewing, it starts low and increases over time. In both instances, heat is lost to the brewing apparatus, the surrounding air and even the coffee itself. As we know from page 69, brew temperature is an important factor in quality extraction and the syphon is one of the only pieces of equipment that, albeit inadvertently, addresses the topic of stable brew temperature.
The result of this slightly different approach to brewing is, unsurprisingly, a slightly different-tasting cup. Vacuum-brewed coffee tends to pull out more of the dark caramel and rich, nutty characteristics in coffee. This is not to everyone’s taste, and often the difference is put down to technique, where it is more likely a product of the brewing temperature.
BREWING WITH A VACUUM POT
Makes: 2 cups
Brew ratio: 1:15 (66 g/2 ¼ oz: 1 litre/1 ¾ pints)
Grind: Medium
1
Weigh and grind 22 g/¾ oz coffee.
2
Boil the kettle with fresh filtered water then fill the lower vessel with 330 g (330 ml/11 fl. oz) of water. (A)
3
Fit a clean cloth filter to the upper chamber and place the chamber loosely over the lower one, then place the whole unit over a heat source. (B)
4
Once the water begins to boil, carefully secure the upper chamber on top (it’s important not to fit this too early; otherwise the brewing water will be too cool.) (C)
5
The boiling water will quickly begin to push upward into the top chamber. The filter can sometimes become dislodged at this stage, producing lots of bubbles, so use a spoon or paddle to centre it.
6
Lower the intensity of your heat source, or move it to one side, but do not extinguish it completely.
7
Add the coffee and give it a good stir. (D) (E)
8
Give it another stir after 30 seconds.
9
After 60 seconds, extinguish the heat source and allow the coffee to filter down into the lower chamber. (F)
10
Pour immediately to prevent the hot glass from scorching the coffee. (G) Allow to cool and then enjoy.
COLD BREWING
Not to be confused with iced coffee (see pages 166–7), cold brewing may seem like a backward kind of approach to a warm cup of coffee, but from a flavour standpoint, there is method in the madness.
Brewing cold results in the extraction of a slightly different range of flavour compounds than those associated with hot brews and similarly, in the drinking of cold coffee we can draw attention to distinct characteristics of coffee origin. Some people find cold brews slightly disappointing since they tend to lack acidity – a result of insufficient heat/energy in the brewing process – but the slant in perspective that they offer over hot brewing methods, for me, makes cold brewing a relevant alternative when exploring coffee’s vast dynamic.
Still interested? Great. There are a few different methods around for making cold-brew coffee. Most of them involve a classic filter approach, where gravity slowly pulls the coffee through a paper, metal or cloth filter over time. Now when I say ‘time’ I mean lots of time – usually over 12 hours. As we know from pages 69–71, rate of extraction is proportionate to heat. Low heat means low energy which, put simply, means things happen more slowly. If you’ve ever poured cold water over a tea bag by accident, you will have noticed this. In the case of cold brewing, the coffee will literally be materializing drip by drip. You can also use a French press or an Aeropress, or indeed any other brewer that doesn’t rely on heat to operate it.
An interesting twist on the cold-brew technique that has proven to curb some of the loss of acidity associated with the method, is to kickstart the operation with a splash of hot water. This initial ‘hot bloom’ helps with the outgassing of the coffee, but more importantly it improves both the potency and the speed of the early brewing process. Once bloomed, the remainder of the brew is done with cold water.
Once brewed, cold-brew coffee can be sealed and kept in the refrigerator for over a week, then simply heated or poured over ice when the feeling takes you. In light of this, I’ve noticed that more than a few cafés have started to load their fridges with their own unique cold-brew coffee product, bottled and branded and available for takeaway.
Although there are now a few products available suitable for cold brewing, they all work under similar principles. On the bottom is a collecting vessel that captures drips of brewed coffee; in the middle is a chamber with a filter and the coffee grounds; and on top is a chamber that holds the water, with a valve that controls how quickly it drips into the chamber below.
COLD PRESSURE BREWING
For a slightly more modernist approach to cold brewing, there is the option of using a cream whipper/siphon.
I have been using cream whippers to make infusions for a number of years now, and they have proven to be very useful tools for ex
tracting the flavours of one ingredient into another. In this method, the cream whipper is used like any other immersion brewer, carefully filled with the correct ratio of coffee and cold water. The unit is then sealed and ‘charged’ with 1–2 cartridges of compressed nitrous oxide (N2O). The gas itself is flavourless, but the physical effect that it has on the coffee and the water is of great interest to flavour enthusiasts.
It has been calculated that a typical 500 ml/17 fl. oz cream whipper, filled halfway, then charged with two 8-g/¼-oz N2O cartridges, would hold a pressure of around 11-bar/160 psi – above even that of an espresso machine (typically operated at 9-bar/130 psi pressure). That’s not to say that it is espresso that we’re making here, as it is the grind size that characterizes that kind of brewing (here we are using a coarse filter), but the pressure initially exerted on the liquid may be enough to force some of it into the coffee grounds – and then back out again once the pressure is released – to form a more complete extraction.
This all sounds rather great on its own, but there are other forces at work here, too. After the initial pressurising of the vessel, the airspace, liquid and coffee will seek to reach equilibrium. This is where the pressures of all three components are equal and can take some time, depending on how the solution is agitated. Under such immense pressure, nitrous oxide will dissolve into the brewing water (like an unopened bottle of carbonated water) and even into the solid cavities of the coffee itself. Both water and coffee then become highly pressurized materials. When the gas from the unit is quickly released, the coffee and water (crucially in that order) will rapidly depressurize. Suddenly then, for a very short period of time, the coffee is at a higher pressure than the brewing water and is bursting to get out. This is very good news for flavour extraction. The violence of depressurization fractures the coffee on a cellular level, causing a huge and sudden increase in surface area and potential volatile extraction points.
This process is known as nitrogen cavitation, and despite having been used in coffee circles for some three or so years now, for me it remains one of the best untapped potentials for delicious coffee out there, hot or cold.
BREWING WiTH A COLD BREW DRIP
This formula makes a concentrate that can be diluted or iced-up to taste.
Brew ratio: 1:5 (200 g/7 oz: 1 litre/1 ¾ pints)
Grind: Fine filter
1
Place the brewer on a set of digital scales. (A)
2
Grind 100 g/3 ½ oz of coffee and place it in the cold brewer. (B)
3
If you wish to ‘hot bloom’ your coffee, set the scales to zero and pour 180 g (180 ml/ 6 ¼ fl. oz) of hot water over the grounds; give the grounds a stir.
4
Fit the chamber on top and set the scales to zero, then add 500 g (500 ml/17 ¾ fl. oz) water, or 320 g (320 ml/11 ¼ fl. oz) if you followed the ‘hot bloom’ method in step 3 (C).
5
Adjust the valve (D) so that the water drips about once every second (E)
6
The brewing process should take 12–24 hours (F).
7
Keep the brewed coffee in the fridge and dilute, or ice, to taste (G). I recommend diluting this recipe with two parts water to one part concentrate.
A WORD ON COLD BREW CONCENTRATES
Your cold brew concentrates will hopefully taste delicious when diluted correctly, but it doesn’t have to stop there. If you’re finding things a bit flat, you can always try a squeeze of lime to bolster the acidity.
Pining for some sweetness? Try blending some with ice and a touch of agave nectar (10 g/¾ oz per 100 g/3 ½ oz of cold brew concentrate) to sweeten it up. Add some single/light cream in there (15 g/½ oz per 100 g/3 ½ oz of concentrate) and you’ll have the most delicious ‘Iced Latte’ you’re ever likely to encounter. Crack open some dark or golden rum and add 20 g/¾ oz per 100 g/3 ½ oz of concentrate to the mix and you’ve got a delicious post-dinner treat that will keep in the refrigerator for over a week.
COFFEE-BASED DRINKS AND DESSERTS
09
STRAITS 7
I was first introduced to this espressobased drink when I was in Singapore, at the famous Oriole’s café and roastery. The ‘Strait’ part of the name is taken from the Singapore Straits, and the seven comes from the use of seven secret ingredients to build the drink. It’s unusual to find good cafés deviating from the conventional family of espresso drinks at risk of tampering with the nuances of their cherished product and upsetting the coffee classicists, so I was quite keen to try this one. It turned out to be delicious: fudgy, wholesome and moreish in a very guilty kind of way.
Discerning the ingredients was not all that easy however. Obviously there was coffee in there and water to brew the coffee, but there was also something milky with a sweetness and a lingering spice. I had to ask three different members of staff before I found anyone willing to even entertain the idea of sharing the secrets of the drink, but following an incognito meeting in a dark alley behind the shop, where I persuaded a nervous bartender to write the ingredients down, I left with a scrap of paper with seven scrawled words: coffee, water, milk, condensed milk, salt, pepper and sugar. No quantities, mind you – that bit I had to work out for myself.
INGREDIENTS
SERVES 1
30 g/2 tablespoons condensed milk
100 g (100 ml/3½ fl. oz) whole milk
5 g/1 teaspoon granulated sugar (or to taste)
a pinch of finely ground black pepper
a pinch of fine salt
30 g/1 oz espresso
1 Add the condensed milk, milk, sugar, pepper and salt to a steel jug/pitcher and stir until combined. Leave to one side while you extract the espresso. Steam the milk mixture to 65°C/150°F, then pour into the espresso in your preferred fashion.
2 It should come as no surprise that this drink cries out for a sugary treat to be served alongside it. My personal preference leans towards a nice crumbly shortbread biscuit. Do it now!
STEPHENSON’S IRISH COFFEE
This is the second book in which I have featured an Irish coffee, and if you’ve read my comments on the drink in The Curious Bartender: An Odyssey of Whiskies, you will no doubt find this an ironic turn of events.
My passion for cocktails, whiskey and coffee ought to elevate my personal appreciation of the Irish coffee above all other worldly things. In fact, the opposite is true. I possess such a senseless hostility towards this iconic drink that an Irish bartender presuming to serve me one would be reduced to tears by cold stare alone – did I mention that I am of Irish descent? And so the paradox deepens…
Recently my distaste has developed into a morbid curiosity. It has become a personal mission to make this drink taste good, while at the same time convincing others that the classic version is bad.
You see, on paper Irish Coffee should work. We have the combined powers of fat, sugar, alcohol and caffeine – some of life’s greatest pleasures – all working towards a common goal of deliciousness. But in mixing sweetened coffee and whiskey together we discover not a grand unification but an abomination of epic proportions. Nuances are lost, subtleties abandoned and we are left with only wood-flavoured coffee and hot alcohol fumes. The purpose of the cream is to temper the heat of the coffee and the burn of the alcohol – a kind of chilled safety blanket – but the damage has been done and no amount of cream can save us. The problem lies less in the ingredients and more in the execution: balance and ratio have been sacrificed for simplicity and ease of service.
My new recipe is effectively a reverse of the classic where warm whiskey-flavoured cream is floated on top of chilled sweetened black coffee. The effect of warm cream on the lips is far more pleasant than dipping your lip into cold cream on top of a classic Irish Coffee only to have it burnt a moment later by the hot coffee underneath. I have also mixed the whiskey with the cream, rather than the coffee, since together these two have proven a powerful affinity (see exhibit A: Bailey’s).
For the co
ffee I recommend using something a little darker roasted, as it’s chocolate, caramel and vanilla characteristics we’re looking for here. Brew as iced coffee, or cold drip, then sweeten it slightly in the service of after-dinner appeal.
INGREDIENTS
SERVES 1
FOR THE COFFEE
150 g (150 ml/5 fl. oz) cold drip/ chilled black coffee (see pages 142–5)
5 g/1 teaspoon granulated sugar (or to taste)
FOR THE CREAM
300 ml/10 fl. oz whipping cream
100 g (100 ml/3½ fl. oz) Teeling Single Grain Irish Whiskey
0.8 g/1/32 oz xanthan gum
20 g/¾ oz granulated sugar
1 Brew the coffee using your chosen method and sweeten to taste.
2 Use a balloon whisk or a free-standing mixer to whisk the cream, whiskey, xanthan gum and sugar until fully combined and smooth.
3 Carefully lay the cream mixture on top of the coffee using a wooden spoon or a ladle. Alternatively, if you happen to own a 500 ml/ 1 pint cream whipper and a nitrogen oxide (N2O) cartridge, add the cream to the whipper and charge it with one 8 g/¾ oz N2O cartridge. Hold the whipper in a warm-water bath or pan at 60°C/140°F, and shake briefly before dispensing onto the surface of the drink.
Note: Both elements of this drink can be stored for up to a week in the fridge, then built together to order.
COFFEE LIQUEUR
High-strength alcohol has many uses, but one of its better functions is as a solvent. Like water, alcohol relieves coffee of its flavourful compounds, and in many ways it does it better. Alcohol is better at extracting coffee oils, has the ability to form stable emulsions (known as nanoemulsions) with those oils, and is useful in the fight to preserve fragile soluble matter once appropriated. The higher the strength, the better the job it does, so my recipe calls for the strongest alcohol you can get your hands on – don’t worry, it’s cut down to drinking strength before serving!