slow down with a coffee

Is it summer yet? The Swallow Coffee shop, Shepherd’s Bush

Coffee Shepherd's Bush
Outside the Swallow Coffee Shop on Goldhawk Road

It was a spring day as we walked along Goldhawk Road towards the Swallow Coffee Shop. A sign, hanging above the door alerted us to the location of the cafe: an image of a swallow in flight, no name, just the image. A nod to the coffee houses of old perhaps that would advertise themselves with a picture above their doorway. The cafe is on the corner of Goldhawk Road and Richford Street and immediately strikes you as being more open and airy than some of the shopfronts we’d passed along the way. The counter is on the right as you go in and coffee is by Ozone.

The cakes looked good but sadly the tempting brownie was decorated with pistachio. Often I find that my nut allergy does have the incidental effect of keeping my waistline down. So sadly, once again it was just the long black that day. There is plenty of seating inside the Swallow cafe and we chose a table up the stairs, on a type of mezzanine level towards the back of the cafe. A map of London was on the wall next to us, which we studied a little in order to discover that a bit of artistic license had been taken with the geography. On the wall opposite, another map showed the region of Hammersmith. There is something interesting in the way that these maps were rendered. What was it that the cartographer intended to convey?

Lubrication station or plant stand
From mirrors to fireplaces and the nature of heat, what do you see in a coffee shop?

A sign above some plants indicated a “Lubrication Station”, perhaps needed by the Swallows on their hazardous migration to and from South Africa. Looking down towards the front of the shop it appeared that there was a mirror that I hadn’t previously noticed on the wall. It was a large, circular mirror. How come I had not seen it earlier as I walked in? And then it struck me, when I walked in, it was not a mirror but another framed map. It seemed as if it had changed its appearance because, from my location sitting towards the back of the cafe, the light was being reflected at a very shallow angle and so I was not able to see any of the ‘information’ behind the glass, only the reflections from the street. What appeared to my eyes as a mirror was in fact a map.

What do maps need to convey? A visual idea of the geography? Or perhaps, the way of getting from A to B. If it is the latter, there is no reason that the map should be geographically accurate and moreover, it could appear as a cartoon like strip of information so that you can ‘read’ your directions as you go along. We came across one such map a few years ago at St Michael’s Mount in Cornwall (see picture). Or, perhaps a more famous example of a geographically inaccurate but perfectly useful map is that of the London Underground. But then, the map may not be about getting from A to B at all but instead, should give an idea of the physical surroundings of a place or indeed could be intended to convey deeper  information such as the poverty maps of Charles Booth. Towards the end of the nineteenth century, Booth walked London mapping the levels of poverty (or affluence) in an area. You can access the maps here. In addition to seeing how some things have changed (or have not), the maps reveal how in London areas of relative wealth so often exist side by side with areas of relative poverty.
what information do we want a map to provide
A map at St Michael’s Mount in Cornwall offers an alternative depiction of the journey from A to B.

Booth apparently come up with the idea of the maps as he had disagreed with the suggestion that 25% of Londoners lived in poverty. And so he’d set out to conduct a statistical survey for himself. Categorising neighbourhoods into different groups according to relative income or wealth, he discovered that, in fact, 35% of Londoners were living in abject poverty, a worse result than he’d anticipated. His findings led to reforms such as the implementation of noncontributory state pensions and to the development of social surveys.

The work of Charles Booth somehow fits together with the research of John Snow who had similarly mapped the cases in the cholera outbreak of 1854 and so traced the source of the problem to the Broad Street pump. New fields of social research were being developed that relied on maps as a base for seeing the world. How we choose which information to include in the map (and by implication which to omit) and the way we choose to display that information, will affect how quickly our audience, or indeed ourselves, can understand the data presented. Some of our decisions are hidden but may affect how the data is later reported in the media. For example, did Booth define “abject poverty” for his maps in the same way as the previous efforts had shown “poverty” levels of around 25%?

In a world with ever growing amounts of data and eye-catching (click-bait) headlines, it is a problem that affects us still. What are the graphs and maps really telling us? Does the data really confirm our existing beliefs or is the devil in the detail of the display? If we find that our preconceived ideas are refuted (or perhaps worse confirmed), do we have the intellectual honesty to sit back, perhaps with a coffee, and question once more both our beliefs and the data that has challenged them? A cafe such as the Swallow, full of maps and prints, with plenty of seating and a light and friendly environment would be a great place to start.

The Swallow Coffee Shop is at 75 Goldhawk Road, W12 8EH

Chemical extraction in a V60

chromatography, paper chromatography, V60

Brewing a coffee, insight into analytical chemistry

Ever considered the connection between your morning brew and a century old technique that, it is fair to say, revolutionised analytical chemistry?

Last week, a new coffee arrived in the post from the Roasting House coffee club, followed shortly by an email with details about that week’s coffee. This is not unusual, the coffee club means that a different coffee arrives every two weeks. What was slightly unusual was the email which started:

“There are some brief tasting notes on the bag of coffee we sent you, but before you go on and read the more detailed description, have a good taste of the coffee yourself….”

The opportunity to do so finally arrived and I prepared a V60. First measuring out the freshly ground beans, rinsing the filter, watching the bloom, then slowly pouring the remaining freshly boiled water onto the grounds, all the while noting the aroma.

Taking this opportunity to slowly prepare (and appreciate) a coffee, I noticed that some of the soluble elements in the coffee climbed the filter paper during the pour. A few hours afterwards, the paper had gained a circular rim of coffee solubles around the top of the paper. Although in many ways quite different, this effect was very reminiscent of the technique of chromatography.

Roast House coffee, tasting chromatography

The coffee in question. What tasting notes would you get if you slowed down and tried this one?

The biggest difference between the behaviour of the V60 filter and “paper chromatography” is that in the former, the bottom of the filter paper is continuously immersed in both the sample (coffee) and the solvent (water). In chromatography on the other hand, a drop of the sample (e.g. coffee or ink) is put onto the filter paper which is then placed in a solvent (e.g. water, ethanol). Different components within the sample travel different amounts up the filter paper depending on how soluble they are in the solvent and how they interact chemically with the filter paper. So different components will travel different distances up the filter paper before they get stuck while the solvent continues to travel up the paper. All else being constant, each component always travels a certain distance relative to the solvent and so this provides a way of separating chemical components ready for further analysis or identification.

Perhaps you remember using chromatography to separate the colours in an ink pen at school? The ink was spotted onto a piece of filter paper and then immersed in water. We watched as it separated into various colours illustrating the number of different dyes that had been used to make up the ink. When used professionally though, the chromatography technique can be used to investigate trace impurities in soil, air, drinking water etc. It has even been used to analyse the components in coffee. From something that can be done in school science, it is an incredibly powerful chemical technique.

What was surprising was that the technique of chromatography was not invented until 1903, while the idea of using paper in chromatography only came about in 1944¹. Those who first used chromatography as a method to identify chemicals (in plants), did so using columns of powder rather than paper. Paper chromatography was invented to investigate the separation of amino acids and specifically was used to understand the composition of the antibiotic tyrocidin¹. Just as the ink in our school experiments separated into different dyes, so the chemicals that they were investigating would separate into different components, different chemicals would stay at different heights on the filter paper.

Since its invention, the technique had been extended to include gas chromatography rather than just liquid and has been developed to be extraordinarily sensitive. It is now possible to analyse chemicals with a mass of just 10^-15 grammes, a quantity which is too small to even easily imagine. Even just a couple of decades after the invention of the technique it could be said:

“Amino acids… could now be separated in microgram amounts and visualised…. (Paper chromatography) would allow one within the space of a week [to do some analysis]… which until then could very well have occupied the three years of a Ph.D….”¹

V60 chromatography chemistry kitchen

A few hours later and the coffee had travelled up the filter paper with the solvent (water).

However, to return to the coffee. Through tasting rather than chemistry, I obtained a toffee aroma, with earthy notes and hints of redcurrant that evolved as the coffee cooled into a sweet toffee taste. The tasting notes further down the email on the other hand said:

“There’s a rich chocolate base, a kind of woody pine taste, sweet summer fruits, even tobacco. Remember, taste it before you judge it! Tobacco notes and woody pine don’t sound particularly appealing and maybe you don’t taste them at all!”

Much more descriptive than my effort. It seems I need to return to my V60 and improve my tasting ‘chromatography’. There are so many ways to slow down and appreciate a good coffee, what do you notice in yours?

A ‘coffee tasting wheel’ can be found here if you, like me, would like to improve your coffee tasting ‘chromatography’.

¹Chapters in the evolution of Chromatography, Ed. John V Hinshaw, Imperial College Press, 2008