Fragrance is the smell of the dry grinds.

Aroma is the smell directly from the cup and is assessed before swallowing. This what we are scoring as we sniff and break the crust when cupping.

The Nose of a coffee is the gases it emits as we drink and swallow. Gases are pushed up to the top of the palate as you swallow. This is why we aspirate (slurp) when cupping. Remember coffee is the universal solvent and also dissolves gases. The aeration of coffee through slurping changes the vapour pressure in the coffee and forces many  gases that have dissolved to turn back into gases.

After-taste is an aromatic sensation. You have residue of coffee in your mouth and throat and this residue emits gases minutes after after you swallow. The tendency is for heavier molecules to leave more residue. This means there is a tendency for after-taste to include more dry distillation smells and less enzymatic ones.

Types of Smells

Divide coffee smells into three.

Enzymatic

Sugar Browning

Dry Distillation

The SCAA flavour wheel from the amazing Coffee Cuppers Handbook is divided into three categories of smell. It is assembled like this to help us understand roasting.

Enzymatic aromas have survived the roasting process without converting into something else. They smell of the living coffee plant and cherry.

Sugar browning caramelisation stage giving us smells of nuts caramel and chocolate.

Dry distillation is burning. This is either by design or accident. If a roaster seeks to reduce acid levels in coffee this will come at a price. Prufrock Considers Dry Distillation aromas to be undesirable. Imagine your coffee tastes very smokey. There is a point in roasting where coffee pops like popcorn. This is called the first crack. If you continue to roast for another minute or two the coffee pops again: second crack. After this point is reached there is no enzymatic material left and the aromas will be all the product of caramelisation and burning.

Flavour Taints

A good cupper needs to do some detective work. A taints wheel allows you to work backwards. You identify a taste, say it’s earthy. Then you locate a similar discripter on the wheel. Work inwards and you notice it’s moved towards fats absorbing odours. Towards External Changes. Imagine butter left open in the fridge next to some smoked mackerel also uncovered. Fats tend to absorb odours. Coffee beans can contain up to 17% fat. The only time coffee was likely to be left near soil is on the farm or at the mill. Many farms lack the infrastructure to build raised drying beds or concrete patios so the beans will have been dried on the naked earth.

Tipping

Perhaps you pick up a smokey carbony taste in what appears to be a very light roast. Beans are not perfectly round. Even the best roaster cannot prevent some slight uneveness in the roasting of beans as they are marginally different sizes and pointy at the tips. At origin beans are sieved through screens to help make them a more uniform size.

Specialty Coffee Association of America’s Grading Standards

http://www.coffeeresearch.org/coffee/scaaclass.htm

Specialty Grade Green Coffee (1):  Specialty green coffee beans have no more than 5 full defects in 300 grams of coffee.  No primary defects are allowed.  A maximum of 5% above or below screen size indicated is tolerated.  Specialty coffee must possess at least one distinctive attribute in the body, flavour, aroma, or acidity.  Must be free of faults and taints.  No quakers are permitted.  Moisture content is between 9-13%.

Premium Coffee Grade (2): Premium coffee must have no more than 8 full defects in 300 grams.  Primary defects are permitted.  A maximum of 5% above or below screen size indicated is tolerated.  Must possess at least one distinctive attribute in the body, flavour, aroma, or acidity.  Must be free of faults and may contain only 3 quakers.  Moisture content is between 9-13%.

 Exchange Coffee Grade (3): Exchange grade coffee must have no more than 9-23 full defects in 300 grams. It must be 50% by weight above screen size 15 with no more than 5% of screen size below 14.  No cup faults are permitted and a maximum of 5 quakers are allowed.  Moisture content is between 9-13%.

Below Standard Coffee Grade (4): 24-86 defects in 300 grams.

Off Grade Coffee (5): More than 86 defects in 300 grams.

Below is a chart for grading coffee beans. It is based on the primary defect and the number of defective coffee beans:

Primary Defects

Primary Defect	Number of occurrences equal to one full defect.
Full Black	1
Full Sour	1
Pod/Cherry	1
Large Stones	2
Medium Stones	5
Large Sticks	2
Medium Sticks	5

Secondary Defects

Secondary Defect	Number of occurrences equal to one full defect
Parchment	2-3
Hull/Husk	2-3
Broken/Chipped	5
Insect Damage	2-5
Partial Black	2-3
Partial Sour	2-3
Floater	5
Shell	5
Small Stones	1
Small sticks	1
Water Damage	2-5

What makes a coffee more Aromatic?

http://www.coffeeresearch.org/science/aromamain.htm

Freshness

There are two issues with coffee freshness. We are looking for an optimum displacement of time from roast. 100 days after coffee is roasted, it should have lost about all the C02 it once contained. As this gas makes its way out of the tiny cracks and caves inside a roasted bean, it brings aromatic gases with it. Studies by VST and Vince Fedele have indicated that a roasted bean contains such an abundance of C02 inside it as to be pressurised up to 12bars directly after roasting. 100 days later this pressure will have completely dispersed. Such a high pressure can cause water that is trying to get into grinds to dispel water as there is such copious out-gassing going on at the same time. For the kind of coffee we use, about 10days later seems to create the right balance of ease of extraction and intensity of aroma.

Green bean freshness seems to promote fresher aromas. The outsides of beans dry out as beans are stored and we have an expression Loomey to describe old coffee. Loss Of Organic Material.

Coffee that has passed the 12 month mark usually has a flatter aroma and will remind you of wood. The dryer outside roasts faster than the moister inside. This coffee is known as past crop. London has developed an acute consciousness of green bean freshness. Some of our best roasters have had a very hard time keeping any variety in their offerings from around Christmas time to April. This is no bad thing. I go out of my way to get a harvest map to every BRaT student that comes through our centre. A customer having an awareness of tropical seasons and our endeavours to keep ahead of the seasons forges stronger links to origin. We encourage our customers in auditing Roasters on quality and greens freshness. This is helping keep more sparkle in the coffees of London. 

The SCAA training Cupping form

Cup of Excellence Cupping Form

Brewer’s Cup Score Sheet

WBC Sensory Score Sheet

They all need the judges to say something about three things

Taste

Smell 

Texture

Divide taste into

Sweet

Acidic

Bitter

We’ll talk about salts in another post.

What makes coffee taste sweet?

There are more than 70 species of Coffea. The specialty coffee world is focused on Arabica. The specialty coffee world definitely looks for sweet varieties. The indigenous variety of Arabica coffee has been shown to be native to Ethiopia and is called Typica.

Typica is still widely cultivated across the tropics and prized for its high cup quality. Typica naturally mutated into Bourbon. This happened on Reunion island in the 19^th centuary and was a big turning point for coffee farming. It was sweeter than Typica.

Being sweet causes problems. Insects love sugar as much as we do. Bourbon and Typica are naturally high in sugars and are susceptible to pests. Most plants need insects to help them pollinate but Arabica is self pollinating. There are fewer insects at higher altitudes and it is no surprise that the heirloom Typica varieties found in Ethiopia are grow above 1200m in a much more insect free zone.

Most of us are new to specialty coffee and are only just getting to grips with varieties because we have recently started drinking coffee. Think about your experience with foods like apples. You would say a Russet was sweeter than a Cox. Apples grow all over the world but you never mistake a Russet for a Granny smith, or a Pink lady for a Golden Delicious whether it grew in New Zealand or Shropshire. Varieties greatly affect flavour and researching them will greatly enhance your coffee experiences. We are good with distinguishing apple varieties because we grew up with them. Varieties greatly affect flavours in and researching them will enhance your coffee experiences.

http://buy.stumptowncoffee.com/varietals/bourbon.html
http://genuscoffea.wordpress.com/coffea-article 

http://www.jimseven.com/2007/08/20/a-varietal-family-tree/

What makes coffee taste acidic?

Acids in coffee are prized. Arabica coffee averages a pH of around 5. (7 is neutral, less than 7 is acidic.) Almost all drinks are acidic. Apple juice and orange juice are about 3pH. Acidity helps make foods and drinks interesting. It makes us feel they are fresh and palate cleansing and fruity and spicy. The thing with acidity is that we tend to enjoy it more if there is sweetness there in equal proportions to acidity. When this occurs we consider a drink to have balance. This is how you can interpret the Taste Balance category on the WBC Sensory score sheet.

Extraction levels affect acidity levels. During a part-tasting exercise the first sip of an espresso tasted in sections as it pours is very acidic. The second sip (lets say at 15 seconds over a 30 second 30g pour) can be shockingly sour. This suggests acids are easy to extract from coffee and come out faster than sugars and alkaloids. Under-extracted coffee might taste more acidic than properly extracted coffee. Malic acid’s melting point is 20degC so it is likely this is one of the first things to make it into the cup.

Altitude has a big impact on acidity. Slower growth seems to give a plant longer to store sugars in the seeds. Check out this article in Roast Magazine:

‘At higher altitudes we tend to produce coffees

higher in perceived acidity. Such that for every 100

meters gained in altitude we can expect a 0.60° C drop

in temperature, and for every 300 meters, a 10 percent

increase sugar production, namely sucrose. What does all

this mean? Higher acidity!’

http://www.roastmagazine.com/resources/Roasting101_Articles/Roasting/Roast_MarApr05_AlchemyPt1.pdf

Cross cultivation can improve plant hardiness and flavours. The Scott Labs scientists were trying to add a phosphoric acid tingle to their coffees. The Bourbon variety is wonderfully sweet but it is not the hardiest variety. Kenya grows two main varieties that are favourites with baristas. SL28 and SL34. SL28 is meant to be the better variety. It is sweet but it is also highly acidic by coffee standards. Perhaps the most acidic of all coffee varieties. It can vividly remind you of Red Currents and Citrus fruits. The variety is not a natural mutation like bourbon, but rather a hybrid. A mix of Yemani Typica and bourbon developed in the Scottish Laboratories (SL) between 1935 and 1939 in Kenya and Tanzania. SL28 and SL34 are both drought resistant and high yielding, they have genetics from Bourbon to bring sweetness to the cup and are more suitable to prevailing East African whether conditions with the Ethiopian Typica genetics from heirloom varietals that it was developed from.

Some coffees leave your mouth feeling just like you’ve eaten an apple. Apples contain malic acid.

This is one of seven principal acids found in coffee. There are 49 acids listen on the coffee research institute’s web page. Most roasters and resources make particular mention of Malic and another 6.

Chlorogenic acid is the most abundant. In Arabica it makes up about 7% of the dry weight of grinds. In Robusta it’s 10% on average.

‘there are basically two

families of these acids; mono-caffeoyl and di-caffeoyl. While

mono-caffeoyl acids readily decompose during roasting, those

of the di-caffeoyl family remain almost unchanged and have

been reported to impart a metallic-bitter taste. It’s no surprise

then that robustas, which exhibit a similar metallic taste,

contain a larger concentration of these acids than their arabica

counterparts.’

What causes coffee to taste bitter?

Robusta is indigenous to Rwanda and constitutes 45% of the worlds coffee production. It is not self pollinating and grows naturally at altitudes between 0-1000m. Plenty of pests at this altitude but Robusta has about half the sugars as Arabica and twice the alkaloids.

Alkaloids are bitter tasting compounds, widely found in plants with many pharmacutical applications. These are part of a plants natuaral defence against pests. Caffeine is an alkaloid, as is Chlorogenic acid. Chlorogentic acid in roasting breaks down into Quinic acid. Think quinine found in tonic water.

Over Roasting causes higher concentrations of quinic acid in the beans. Prufrock looks for an optimum roasting balance between very light roasting that may leave a chalky sourness and over roasting that will make the coffee much more bitter.

http://www.coffeeresearch.org/science/bittermain.htm

What makes coffee taste sour?

Roasting has a role to play in optimising Citric Acid levels in the cup. Citric acid tastes sour. It is a positive sensation at lower concentrations. Medium roasts contain about half as much citric acid as green beans. Unripe coffee will have higher levels of citric acid. In a fruit, citric acid converts into sugar so if coffee cherries make it into the washing station unripe, you can expect sourness in the cup. The extreme of unripe is visably blonde in colour and we refer to these as quakers. They are sour and smell of peanut. Pick them out. Coffee scoring 85% and higher shouldn’t contain more than one quaker per kg.

If beans have fermented or been allowed to dry on the tree we encounter a much larger quantity of a familiar acid. Acetic acid is found in vinegar and is very sour. This is the fourth most concentrated acid usually found in brewed coffee.There are higher proportions of acetic acid found in washed coffees and very light roasts. It moderate proportions it can add a positive winey taste to coffee but it can certainly taste like ferment and in high concentrations is a fault. Roasters are tempted to roast darker to evaporate off this acid to reduce sourness. This certainly works. We are looking for coffees that through careful picking and processing have not develope an imbalance of acetic acid.

The other principal acid in coffee is phosphoric acid. It is tasteless but creates the tingle on the tongue that is prised in coffees like Kenyan SL28. This same acid is found in almost all fizzy soft drinks. More about this in Tactile

This is a very lengthy blog about water and sums up most of what we are focused on in our production of water on our RO. We have plans to market out RO water for customers to take home so they can brew with water that we have tried to optimise just for you. In the mean time, ask one of our baristas who might slip you a litre or two for the weekend.

Thanks must go to James Hoffman for the ball bearing analogy.

What’s in water?

Solvent

Water is known as the universal solvent as it dissolves more substances than any other solvent. It is what we use to dissolve coffee solids. Water can dissolve liquids, solids and gases.

Rain water dissolves CO2 in the atmosphere as it falls and becomes mildly acidic. The rain falls to ground and one of two things may happen to it before we are able to drink it. It may fall into a catchment area and be collected in a reservoire. Otherwise it starts to percolate through rock. Remember it’s now mildly acidic so it starts dissolving salts and minerals as it sinks into the water table.

Solute

Water will Like with whisky, it is the impurities that give water it’s flavour.

f the water is hard like London water, it contains a lot of dissolved material already such as

Calcium and Magnesium. This material is the solute. It is the solute that gives water it’s flavour and and alters it’s mouth feel. The dissolved coffee in a brew is also solute.

Check out Prufrock’s Jeremy Challender on the BBC Breakfast’s water tasting panel this May.

http://www.bbc.co.uk/news/magazine-22247668

http://www.everpure.com/know%20your%20water/Pages/Whats-In-My-Water.aspx

What is optimum?

The Speciality Coffee Association of America have set a standard for water in brewing coffee.

http://scaa.org/PDF/ST%20-%20WATER%20STANDARD%20V.21NOV2009A.pdf

Prufrock follows this guide but we are OK with softer water as low as 80ppm. We certainly prefer neutral water 7pH. Brewing recipes are optimised with the brew water through trial and error. Optimum extraction may require a slighly different grind size, contact time or water temperature depending on the brew water’s chemistry.

Hard water/Soft Water

For coffee brewing the important thing is not too much mineral content (above 150parts per million) and not too little (below 80 parts per million). The problems at both ends are to do with under-extraction. We find water is a better solvent around 120-150ppm. But we find 150ppm begins to cause scale formation in equipment.

Excessively hard water cannot dissolve as much coffee as quickly it as it is already full of minerals. Too soft and it expends most of it’s energy holding itself together so is not as good a solvent.

To explain this properly consider you had a bunch of ball bearings, all with a magnetic charge. They represent water molecules. Water molecules are attracted to each other through hydrogen bonds. Hydrogen keeps grabbing on to Oxygen and for every one Oxygen atom, you’ve got two Hydrogen so there’s a real tussle going on. All your ball bearings are clumped together.

Now lets say you threw in a little sprinkle of plastic beads. These represent the dissolved minerals in hard water. The beads prevent the water sticking together quite so much as they are in the way.

If we threw a massive amount of beads into the mix, the ball bearings would be smothered and it would become harder for them to stick to each other or to anything else. This state represents what happens when you try to brew with very hard water full of minerals.

Temporary Hardness/Permanent Harness

Boiling water gives you the difference here. Minerals drop out of the solution and form scale. The permanent hardness is what’s not precipitated out of the water after boiling.

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How to taste water?

Pure water is odourless and tasteless. When tasting water you are trying to zone in on impurities. Hold it in your mouth for at least five seconds before swallowing. This should allow you to perceive

more gases, and give your taste buds more time to determine tastes.

How to smell water?

Sample your water in a tall glass only about one third full. Sniff actively; several short sniffs to get gasses up to your receptor cells at the top of the soft palate. You can’t smell anything that isn’t a gas.

Water that is good for coffee should be odourless with no smell of sulphur. We know water can dissolve gases so like we do when cupping coffee, we can aspirate water and by nebulising it into tiny droplets we can try to extract some gases out of it that we can then smell.

Flavours in water

Follow this link for a water flavour wheel and a comprehensive list of likely sources of tastes and odours in water.

http://dwi.defra.gov.uk/research/completed-research/reports/0820.pdf

Tastes

Salty: might be caused by Chloride in ground water

Bitter: most likely be caused by Calcium Carbonate or Sulphate.

Sour: Magnesium is considered to have a sour taste though it is an alkaline mineral.

Sweet: Aldehyde. (Aldehydes are used in making perfumes and get into public water as a bi-product of the chlorination of amino acids.)

Aromas

Earthy/musty: bacteria

Chlorinous: Chlorine and Chloramine in antibacterial treatment.

Grassy woody: Algae and bacteria. Leeching of chemicals from grass.

Swampy:Sulphurous/decaying

vegetation/septic/Bacteria.

Fragrant: Aldehydes from Ozoneation water treatment.

Fishy: Algae

Medicinal: Phenols, Chloramine (Chlorine with Ammonia added to make it degrade slower)

Chemical: Phenol, Iodine, Flouride

More on Taints

http://www.jwrc-net.or.jp/aswin/projects-activities/rd_files/jp-sg_symposium/2012_07_04.pdf

This link for comprehensive courses in water management

http://water.me.vccs.edu/courses/env110/ENV110Lessons.htm

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How to talk about water

Most literature on water’s aroma is focussed on taints and the word odour replaces aroma.

As with espresso evaluation, it is necessary to describe odour, taste balance and tactile characteristics of body, round and smooth.

Salty taste will generally mean acidic, bitter taste will mean alkaline. Hard waters will usually seem to have more body than soft waters.

PH

Potential Hydrogen. More Hydrogen plus (H+) Ions means more acidity. More Hydroxide Ions (OH-) means more Alkalinity or basic. The pH scale is logarithmic. A change of 1 number on the scale of 1-14pH means ten time the number of H+ or OH- ions. 0 is acidic, 7 is neutral, 14 is basic.

http://anrcatalog.ucdavis.edu/pdf/8118.pdf

Prufrock notices a significant drop off in coffee flavours if water has a pH of over 8pH. Some

great baristas we know favour slightly acidic water for brewing ( though not below 6pH) but as a rule, pH7 has been our preference.

Dissolved Oxygen?

Plants and animals consume oxygen in water. Warmer water contains less dissolved oxygen.

Running water from a stream contains more dissolved oxygen as it is churning. Think fish tank.

At the water treatment works (read on) water is churned for the purpose of dispelling dissolved CO2 which raises pH levels.

High oxygen levels or churning helps us in brewing as it helps dispel C02 faster. This is still debated. Here is an experiment at Counter Culture that found a majority of people preferring samples prepared with water that had boiled for one minute over water that had been brought to 200deg F then brewed but the least favourite was prepared with water that had been boiled for 5min.

http://www.trifectaexperience.com/uploads/documents/b9d7b1ff-6b99-4082-982e-b3930d6a0072.pdf

TDS

Total dissolved solid. Everything in the water other than H20 and solid particles. So that’s the minerals, salts and metals. We have an RO system because we can’t effectively lower our TDS below 200ppm without one.

Suspended Solids

These are undissolved particles that float in the water be they bacteria or colloids. Suspended solids cause higher turbidity in water. (light absorption). They can add to water’s texture but are generally undesirable as they can carry pathogens that are harmful to health and will block the membranes in carbon blocks faster.

In unfiltered water there are two types of organism- the cyano bacteria known as blue/ green algae, and actino mycetes, responsible for the damp or earthy smell.

Dr Andrea Dietrich, professor of civil and environmental engineering and a water tasting expert at Virginia Tech in the US comments:

‘What people describe as an earthy or musty ‘taste’ will usually occur in water as a by-product of the ecology.

Given that odours can cue recall of a memory – an “earthy” flavour might evoke the joys of the hills and valleys to one person, but an unpleasant damp-in-the-basement experience to another.

http://en.wikipedia.org/wiki/Suspended_solids

How do filters work?

Most filters involve activated carbon in the form of granules, powder or a block which is effective in removing excess salt and other dissolved minerals, taste and odour, heavy metals, micro-organisms, nitrates and pesticides. Carbon from things like burnt coconut shells is extremely porous and is therefore very good at absorbing chemicals, bacteria and minerals. A gram of activated carbon can have a surface area in excess of 500 m2.

Ion Exchange Filters

Most filters like Britta Jugs or the scuba tank looking cartridges commonly used in cafés contain lots of tiny resin beads that attract and capture the the positively charged calcium and magnesium (carbonates) as they move through the system. The resin has a negative charge. It is this that attracts the positive charged calcium and magnesium. The beads have a coating of sodium. This is released as the calcium is attracted. Sodium is a soft material and takes the place of the hard material. The SCAA recommends less than 10mg per Litre of sodium for optimum extraction and taste of coffee.

Water softeners like this do not filter water. They just replace hard ions with soft sodium ones. They certainly improve the taste of London water and can reduce harness fairly effectively but we have found they cannot reduce London’s hardness which averages 320ppm much lower than 200ppm which means scale is still an issue.

http://en.wikipedia.org/wiki/Ion_exchange

http://www.everpure.com/know%20your%20water/Pages/Understanding-Water-Softening.aspx

Reverse Osmosis

In nature water moves through a semi-permeable membrane to create a balance in concentrations of solute and solvent. That’s why salinity in waterways can kill aquatic plants as they loose their pure drinking water into the salty waterway.

Reversing this process by using pump pressure means pure solvent H2O will gather together as almost pure water. Water molecules are smaller minerals so the membrane perforations are small enough to only allow H2O through.

The system then allows us to create a blend of pure RO water and source water. The source water is partially filtered for taste and odour through activated carbon

We use an Everpure MRS 600 RO system.

http://www.everpure.com/know%20your%20water/Pages/Whats-In-My-Water.aspx

Large Scale Treatment

Chlorination can deal with fishy, grassy, or flowery odours and with iron and hydrogen sulphide (Rotten egg smell). Follow the link for a great diagram and description of water treatment plant processes.

http://water.me.vccs.edu/courses/env110/lesson1.htm

On a massive scale, the treatment of water is much the same as what happens inside a filter cartridge. Water is first churned to dispel CO2. The main difference here is the use of Chlorine or Chloramine for disinfection purposes. Carbon sedimentation is used to clarify the water and remove bacteria, minerals and suspended solids. Ion exchangers are not generally used as they are expensive so our tap water in London averages around 8.2pH which is most unsuitable for coffee.

London is considered to use fairly low Chlorine levels.

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This recipe is included in the recently published for Hario in Brewed By Hand’s waterproof brew chart.It also features amazing recipes from James Hoffman on the V60, Ross Brown of Brown’s of Brockley on the French Press and James Bailey at Workshop Coffee on the beautiful Hario Woodneck.

Safety: When heating it is important to have the filter fitted properly to the base of the upper chamber and clamped to the bottom of the stem with the steel chain resting on the floor of the bottom chamber. This chain provides a nucleation point for bubbles to form as the water reaches 100degrees Celsius. This prevents the water from getting superheated which can cause the glass chamber to crack.

1. Temp: 94degreesC
Syphon is our most temperature stable brew method. Water boils in the bottom chamber and is delivered into the top chamber ready for coffee to be added. Warm air bubbles fizz up through the stem that prevent the temperature profile from dipping. The temperature would climb very gradually but we can ease turn down the heat source by half and hold the water temp wonderfully stable at 94degreesC.

2. Dose: Coffee 15g (fresh)-Brew water 230g (pH Neutral, ppm 80-120)
With Syphon you can add a small amount of coffee to a large amount of hot water which flattens out the temperature profile even more.

(Drip coffee has a very contoured temp profile as we are gradually adding water to coffee rather than coffee to the water.)

3. Time
Bring your Syphon to the boil with the top chamber loosely sitting in the bottom chamber without being sealed. Once water in the lower cavity has hit a rolling boil, you can gently seal the top cavity to the bottom cavity. The bottom cavity will pressurise and expanding air will displace the water up the stem into the top chamber. Reduce heat by half and brewing can commence.
0 sec: Add the coffee and with minimal agitation, ensure all the grinds are wet.
30 sec: The stable temp needs a stable method. Stir with a cross shape (North, South, North, South, East, West, East, West) only to break the crust. Not too vigorous. Nothing you can’t replicate.
1min: Remove from the heat source (the small amount of water in the lower cavity can be a bit hot so it’s best to remove the syphon from the burner). Give the slurry one gentle 360degree circular stir to induce the draw-down and to make an even dome shape out of the coffee bed. This helps ensure equidistant paths through the grinds en route to the bottom chamber to promote more even erosion of grinds.
1:30sec: Draw-down complete. Immediately remove the top chamber that contains the spent grinds.

4.Grind:
We grind around the same size we do for a 2min pour-over but remember contact time and grind are optimised for flavours, taste and texture through trial and error. Experiment with longer and shorter contact times with correspondingly coarser and and finer grinds. Syphons prepared with longer steep times tend to have a rounder, smoother mouth-feel but perhaps less aroma. Most baristas tend to favour shorter contact times.
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Here are some questions we were asked by Esquire recently concerning some research they were conducting into trends in coffee. As it is Summer we thought you might like to hear about our thoughts on cold brew.

Firstly, do you know how long cold brew has been in the UK?

Cold brew methods emerged in the UK around the summer of 2010 and where informed by the uniquely independent Japanese coffee culture. Much of the brewing equipment that wasn’t homemade was developed in Japan harnessing its beautiful glass blowing traditions.

How exactly does the cold brew process work?
There are two categories of cold brewing; drip and immersion. The drip method quite literally calls for cold water to be added drip by drip through a precise flow restrictor into a bed of ground coffee that is suspended above a filter. Gravity fed liquid coffee then collects in a jug underneath. The drips need to be dispersed evenly across the surface.
With our Hario (TM) brewer, drips are landed onto a steel pin that cascade in smaller droplets across a paper filter that is laid over the coffee bed. This prevents the uneven erosion of grinds.

Prufrock’s method calls for a two second interval between drips over a period of approximately four hours.

Try collecting the brew in sections (say every half hour) and liquid blending separate parts of the extraction to optimise the taste and strength. We brew with the target ration of 65g/L but entry level brewing equipment won’t give pinpoint control of the drips per minute rate. Liquid blending allows us to zone in on optimum extraction rather than just sticking to a set brew ratio.

An easy immersion method is the Toddy (TM) performed with a very fine-mesh nylon sack of coarse (cupping) ground coffee steeped to taste in cold water for several hours. Use a ratio of around 70/L. Drain all the liquid from the grinds once the desired taste is achieved. The toddy much like an home brewing keg has a tap at the bottom for draining. For greater clarity, fine sediment can be filtered out after brewing is complete with a paper or nylon filter. Better still, fine particles can be sieved out using a 1/4mm screen prior to brewing. Store in the fridge for not longer than two days.

How does it change the taste of the coffee?
Expect much less aroma and muted acidity but a syrupy port-like textural quality that makes a great substitute for Campari in a Negroni and mixes fantastically well with tonic. For best results choose brightly acidic and lightly roasted coffee and grind fresh.
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