vrijdag 26 juni 2015

KdW Speedster with "Lever Style" hand pump pressure

A year ago I wrote a blog about Jip van Neerven, who was working on a modification of a Kees van der Westen Speedster espresso machine for his graduation project.
Jip van Neerven and modified Speedster
Today, having graduated, he presented the machine with his beautiful modification during the big exhibition of all graduated of his year.

Detail of pressure chamber device

Switches to open/close the pressure valves
The magnificent Speedster is already a fairly silent machine in the standard version with a rotation pump, but now the pressure needed to extract coffee is generated by a simple bicycle pump and no motorized part is active at all, much like in a lever espresso machine.

Pressure setting slider

Jip van Neerven explaining his work
The Jip-Speedster emulates a lever in more ways than just the pure "silent mode". It also mimics much of the beautiful pressure profile that makes many people love espresso from lever machines.

The bicycle pump is actually used to pressurize two chambers in the tall and slender steel column that's towering over the Speedster. Target pressure is about 10 bar.

The reason for having two chambers, one big, one smaller, instead of just one pressure source: once a the valve of a chamber is opened and the pressure used to push water of 92.5ºC through the coffee puck, the pressure drops somewhat in the big chamber (say from 10 to 9 bar). If one opens the valve of the smaller chamber, this pressure drop is much more significant.

Bicycle pump pressure gauge
This helps to get an extraction resembling a lever machine profile: pre-infusion at line pressure, extraction starting at 9 bar, slowly dropping and then, switching to the second chamber, a pressure further declining towards the end of the espresso shot.
Pressure gauges on the chamber column
Jip invited me to do some more testing soon. Today, he only had a very dark roast on the grinder with beans that glistened from coffee oils, so any subtleties in potential taste would remain hidden. We will next test with some different beans!

Some of the heavy Jip van Neerven coffee tampers

In the video, Jip explains how he has mainly focused on the technical aspects, wiring, hydraulics, and has yet to learn about coffee, so he is definitely not posing as a coffee connoisseur and he is not all all pretentious about such things. He enjoys learning and told me he looks forward to my comments later on when we can work together.

I think it's a brilliant test bench of hardware and I applaud Kees van der Westen for making all that hardware available for this project. He is not at all afraid that people will damage his brand image and I think that's a very generous standpoint.

Kees is abandoning his Idro lever production and I like it that there are others, even with his full and loyal support, to acknowledge the beauty of lever extractions, who like to experiment to emulate this.

Jip, meanwhile, is also developing a much smaller machine, La Pavoni size, with such pressure profiling.

The Netherlands is breeding espresso innovators, like Jip van Neerven and Wouter Strietman of the ES3, who also enjoyed his internship at Kees van der Westen's workshop, and who even works with KvdW's metal work engineer.

woensdag 24 juni 2015

A visitor from Costa Rica

From Hungary, Laczkó Gábor emailed me last night to tell me there is a young coffee farmer currently in Amsterdam and he suggested we meet, so we did!

On her way to a swimming competition in Alkmaar, Marianela Montero took a small detour to my house to taste some espresso from Burundi beans that I roasted a few weeks ago.
Marianela Montero and Patrick Brouwer enjoying coffee
Patrick Brouwer, a colleague who came to pick up some materials, also joined in.

After her graduation from the National University of Costa Rica’s International Business and Trade School, Marianela has been traveling the world over the past year, exploring the coffee world abroad. This trip has taken her to Little Italy in San Diego where she worked at a roastery. She also had the opportunity to visit the recent SCAE event in Seattle, further expanding her already vast network of friends and colleagues. Ultimately, she plans to take all she learned back home and help to grow the market for the farms of her family.

I suggested that while still in Amsterdam, she should meet Kees Kraakman of Stadsbranderij Noord who knows how to connect a number of micro roasters. They could be great business partners in the future.

There's a feature about Marianela on the San Diego Coffee Network site:

She also has her own blog / website: http://cafeticanela.com
Marianela Montero & Frans Goddijn
Wishing Marianela all the best and hoping to meet again and share more coffee talk!

zaterdag 20 juni 2015

The Instant Nespresso Experiment

Text: Jan van der Weel
Pictures: Frans Goddijn

James Hoffmann recently wrote a very interesting article about Nespresso. One of his findings was the extreme high extraction yield of Nespresso. Nespresso coffee extracts better on low end equipment than most high quality coffee in combination with high end brewing equipment.

“This is pretty impressive work for 12 seconds of brewing. If you’ve played with things like the EK-43 then your target extraction range probably moves from 18-22% of the Gold Cup standards, up towards maybe 20-24%. If this is your window then a Nespresso capsule hits that window regardless of where you pull it, between about 25g of liquid and about 60g of liquid.”
Nespresso cups opened up to test roast color on the Tonino device
He wrote that there’s a lot speculation about the technology Nespresso uses. That inspired us to read into coffee patents that might explain this phenomenon. Reading these patents made very clear that the coffee industry is technologically very advanced. We saw many interesting coffee patents that are owned by Nestlé, the producer and brand owner of Nespresso. We specifically read the patents that were related to ground & instant coffee coffee. 

A few findings from this small desk research. One Nestlé patent is about the improvement of the aroma and flavour of instant coffee. This can be improved by spraying an aroma containing substrate to instant coffee. The patent states that it is equally applicable to other beverage powders such as roast and ground coffee powders. Another Nestlé patent is about the improvement of the taste and aroma instant coffee. This can be improved by adding ground coffee to instant coffee. One thing became clear after reading the patents. We don’t have to assume that industrial instant, ground or whole bean coffee is 100% pure. Things might not be as they seem.

Maybe not all of the technology that Nespresso uses can be found in patents. After reading the patents and rereading the James Hoffmann article a very simple idea popped up in our minds.

Maybe Nespresso is adding instant coffee to the Nespresso cups to increase the extraction yield?

This idea is so simple that it could be easily tested. Two days later we did an experiment to test this hypothesis.

We made a few assumptions for the experiment. First we thought that ground coffee would be very difficult to extract in cold water (room temperature). Secondly we assumed that instant coffee would be easy to extract in cold water. By diluting regular ground and Nespresso coffee and comparing the extraction yields we would be able to check if we were on to something. We also checked the extraction yield of instant coffee, to check our second assumption.

To be sure that all of our samples would be properly mixed and measured, we would put them in the laboratory centrifuge.
We needed Nespresso, regular ground coffee and instant coffee for the experiment.  We decided to use Nespresso coffee that was supposed to be lightly roasted. The sales person of the Nespresso Boutique in Amsterdam’s PC Hooftstraat advised us to try the Nespresso Cosi. My girlfriend Aura and I sipped the coffee and we both agreed that it tasted like lightly roasted coffee and that it matched the advertised flavour profile.
Pure, lightly roasted East African, Central and South American Arabicas make Cosi a light-bodied espresso with refreshing citrus notes.
Besides Nespresso I bought a package of Nescafe instant espresso coffee at the local supermarket. The other coffee we used was an Ethiopian Limu roasted by the Dutch Bocca coffee roasters. For the experiment we used filtered water with a TDS of 260. Extraction yields were calculated by using a 4th Generation VST LAB Coffee Refractometer and the VST CoffeeTools android app.

Nespresso grounds ready to test

Before diluting the three coffees in water we first measured the color of the coffee with the Tonino color meter. This gave some unexpected results. When measuring the Nespresso Cosi the display showed a score of 31. This scores means that the Tonino color meter ‘sees’ a very dark roast instead of a light roast.
31 points on the Tonino roast color analysis device
This was rather strange. What makes a light Nespresso roast to look like a very dark roast? The Nescafe roast scored 86 points on the Tonino. That score equals a medium light roast.
Nescafe solids ready for color analysis
86 points on the Tonino

What makes this light Nespresso roast look like a very dark roast?
Next was the preparation of the samples. We prepared 7 samples. The first two samples were made by diluting Nespresso with cold water. The first sample was shaken and the second was stirred. We wanted to know what method gave the best extraction yield. The best method would be used in the preparation of the following samples.

Weighing off Nespresso grinds

Sample shaken, not stirred, ready to centrifuge

Coffee sample centrifuge at work

Out of the centrifuge

The other samples consisted of diluted Nescafe Espresso and diluted ground coffee. We made three samples of ground coffee with a different coarseness. In table ‘results experiment’ you can see the results of the experiment. The results do confirm that you can easily make coffee from instant coffee and cold water. The results also show that by stirring and centrifuging finely ground coffee you can extract up to 14.5% from the grounds. This was really something we had not expected. We thought that this value would have been much lower.

VSTlabs refractometry

Stirred sample

This experiment does however not show that there is instant coffee in Nespresso.

Table: results experiment

Dry coffee weight (gr)
Water (gr)
Mixing method
Measured TDS
Extraction Yield
Nespresso Cosi
Nespresso Cosi
Nescafe Espresso 100% Arabica
Nescafe Espresso 100% Arabica
Limu (Bocca Coffee Roasters), espresso ground
Limu (Bocca Coffee Roasters), finer ground
Limu (Bocca Coffee Roasters), even finer ground


Samples of Bocca roasts out of centrifuge

Nescafe samples

The experiment did not show that there’s instant coffee in Nespresso. The experiment however did show some remarkable results. At first we find it rather strange that the color meter measured lightly roasted Nespresso as dark roasted coffee. We can not explain this phenomenon.

Secondly this experiment shows that ground coffee seems to be quite easily extractable by stirring and centrifuging. Maybe the process of making a cold brew coffee can be sped up by such a kind of method. Maybe this is worth further investigation. Centrifugal brewing is something that has been done in the past. Douwe Egberts has even made a cheap home espresso machine that was built upon this principle.

The experiment shows that ground coffee seems to be quite easily extractable by stirring and centrifuging.
Thirdly the experiment seems to indicate that something else is going on. We are looking forward to the upcoming posts by James Hoffmann about Nespresso. Maybe he will be able to explain what’s going on.

Sediment at the bottom of centrifuged Nescafe solution

Nescafe sediment droplet in the sun
Nescafe sediment droplet after some minutes in the sun

dinsdag 16 juni 2015

Wall mounted espresso grinder made from scrap parts

Peter van der Weerd from www.kafko.nl tells me how he got an old broken fully automatic "egro" espresso machine. He took it apart , set aside the rotation pump for later use and built his own wall mounted espresso grinder using parts of "egro" grinder segments of the automatic.

He made the wall mount himself, replaced the ball bearings, added a timer doser and a nice old "coffee" switch, added a hopper from another scrapped machine and now he has his own little handy espresso grinder to test the espresso machines which he repairs every day in his workshop:

Getting the new anti-vac on my old La Pavoni

Most La Pavoni home levers have the pressure relief valve but no anti-vac so at startup you need to release some steam to get up to the correct temperature and after turning it off the lever is sometimes "sucked" upwards by the under-pressure in the boiler.

La Pavoni puts more modern valves on their new models. These have two-in-one: it's a pressure relief valve that opens when a maximum pressure is reached, to avoid breakage, it releases some steam during warm up and it allows air to get sucked back into the boiler when cooling down.

A fine reason to go visit Peter van der Weerd in his www.kafko.nl workshop, and enjoy his company, chatting about things related to coffee machinery, life, family, pleasure... and coffee.

Peter van der Weerd upgraded my old La Pavoni Pro with this new valve and in the process he did a check up of the machine, replacing a rubber seal in the boiler cap and also replacing the heating element which had suffered some overheating in the past and turned out to have less than "infinite" electric resistance which might cause a shock someday.

Taking off the old pressure relief valve

Steam wand & old pressure relief valve off

Taking a look at the bolt inside the boiler

Taking off the pressure gauge

Preparing to take off the heating element

Looking from the open bottom up to the bolt of the oldvalve

Taking off the old valve

getting the new valve ready

Inside of the new valve, check the anti-vac

close up of anti vac

Holding the bolt to fasten the new valve

Sliding on the new valve combination


New element in, connecting the copper tube to the OPV

Copper tube to OPV fastened

Bending the copper tube

Machine on, checking for any tiny steam leaks

New rubber seal on cap

Shortened the inner bolt a bit
Checking the new combi valve:

The old over-heated element, looking red hot

Over-heating made it soft and flexible

Easy to bend by hand after overheating