Nice gallery, and writing on ergonomics; carpal tunnel syndrome.
Category Archives for Espresso geekery
Water and coffee: Water quality in brewing
Coffee as a drink, is mainly water, and the quality of water directly relates to the way we perceive flavours, this is important both in espresso and soft brewing.
The flavour of acidity in coffee is effected by the ph, and chemical make up of the water. High acid coffees can loose their acidic flavour because of water makeup, and espresso machines become scaled.
We all use industry standard filter kits on water for brewing, which are really just a starting point for treatment, but gets very expensive to go to next step.
lime scale build up
When you buy a Slayer, you only get a warranty when proper water treatment processing is done, in NZ this costs over $5000 to set up. This is the next step in filtration, but something which isn’t viable in a wholesale cafe market.
The new dual boiler espresso machines have flow restrictors with hot water running through them which scale up and block injectors quickly, causing regular problems in regions where water has a high TDS.
The water filters we use are Everpure 2CB-GW, which do the following:
- Reduces fine dirt and particles
- Carbon block filter polishes water for high quality beverage and food applications
- Reduces chlorine, taste, odor, and other offensive contaminants
- Reduces limescale build-up that can damage the machine
As you may know, even with these filter kits, lime scale does build up, and fast depending on your water content. So globally every espresso machine has this problem.
I wonder how water quality treatment in coffee will progress, will we see better filter kits at affordable prices, will we be running ‘bottled’ water through our espresso machines, or will we continue to need to de-scale espresso machines every year or so?
Roasting coffee for black or with milk.
I have recently decided to change our approach to roasting coffee, and want to relate it specifically to whether it is going to be drunk black or with milk.
I want to bring out the best flavour in each origin but it seems clear to me now that you want very different flavours in the coffee, depending on whether it has milk or not.
Black coffee I want the flavours to be fruity sweetness– like the coffee cherry looks like it might taste. But these flavours turn sour when combined with milk, so I want caramelised sweetness to work with milk.
This mindset covers soft brewing and espresso, and I am currently developing (june2012) new roast profiles for each origin: but on the whole the Americas will be both black and white, but some Africans may be black only.
This will be presented on our new retail bags as, recommended Black, recommended White.
During June July we are now receiving our fresh harvest of most origins. These will be tasting extra good while they are fresh, and I will use these as a conduit to roll out the new roast profiles, as they will all be tasting good and this will hopfully help customers with the transition.
The first question to ask someone is buying retail bags is “do you take milk with that?”, (where it used to be “is it for plunger or stove top…”) and lead people towards origins based on white/black, then we can better explane flavours, and encourage customers to be looking for fruit sweetness in acidity for black, and bitter sweet choc for milk etc.
This partly came from knowing our coffees make great espresso, and most of our business is espresso, but trying to make single origins really good with milk and black is not poss with many origins.
What this means is we will be doing Single Origin Espresso light roasts, which (for me) is a very exciting new flavour experience which works very well with most of our coffees!!
The Don and Taddesse roasts are the lightest they have ever been (just enter second crack) and we might find it usefull to mainly recommend blends to people who like the big bold “coffee” flavour, as these taste awse with milk!!
This enables me to bring out more interesting flavours for the black coffee roasts, not having to worry if about it being drunk with milk and customer thinking we don’t produce a great product.
I will still try to keep a spread of available flavour thru our origins, bringing out certain characteristics in each origin to get a good spread, but it is a move towards emphasising fruitiness in black coffee.
René
Paddle / pressure profile / pre-infusion brewing
Renés notes from talks with the designers and builders of:
Slayer, Marzocco, Synesso
Different ideas:
Pre-infusion with set pressure- just like the bloom stage of soft brewing, wetting the puck to swell it and fill all the gaps between grind, to ensure full saturation, to allow brewing to start without pressure so no channeling will occur. This also will stop “fine grind” being pushed thru the gaps to the bottom of puck and clogging, with PI they are trapped where they sit as the coffee swells.
Post infusion with set pressure- allows the bar pressure to be reduced at end of the shot- to be able to continue extracting good solubles and flavours out of the coffee without over-extraction with high pressure, just like a lever espresso machine
– direct response in bar pressure, relating to changes on made on paddle, visible on manometer,
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Slayer: Jason Prefontaine
Slayer has a 2 stage brewing potential, pre-set on both stages- ie 3 bar, 9bar
It uses a mechanical brew head (and paddle) to switch between 2 pipes feeding hot water,
Stage 1- is Pre-infusion (using an adjustable tap inside machine) set on eg:3 bar,
Stage 2- to select main brewing pipe, eg:9 bar.
Towards the end of shot you can return paddle to stage 1, but it won’t simply return to 3 bar, can vary greatly in post-infusion stage due to residual pressure remaining in puck. So post-infusion isn’t very reliable/ useful.
Weakness- mechanical brew head requires bi monthly seal changes inside head, requiring full machine shut down.
totally manual means its not possible to perfectly replicate shot profiles in cafe.
Recommends only using one brew head at a time as muli use will reduce overall pressure on each group due to only 1 pump. (same as most machines which don’t have pump per group)
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LM: Scott
La Marzocco Strada (MP) Mechanical paddle and (EP) Electronic paddle
MP- has a variable brew pressure paddle, and manometer dial on top of each group to see pressure changes. But usability is very hard as the amount of room you have to move with paddle from 0 to 9 bar is about 1cm, I couldn’t get any useful pre-infusion from these machines, would always show no pressure on dial or quickly ramp up to 9 bar. Therefore this seems useless to me, and almost everyone I’ve talked to doesn’t use pre-infusion on these machines.
EP- Uses a geared pump to progress “varied pressure brewing” (unique to EP I think) it electronically changes pump speed to deliver diff bar, all water is delivered via one feed.
Uses electronics to program different brew pressures during extraction. You can chose any pressure settings, or run shots manually with paddle. No manometer dials on group heads. This machine is touted as designed for pressure profiling, but would be best used for pre and post infusion.
Weaknesses:
Both Strada’s also have wear issues with the mechanical group head, need seal replacement regularly requiring full machine shut down, and has wear / casting issues. Also paddles don’t like hard use, it misaligns internals making the paddle useless till repair replace internal parts which have bent or broken.
Recommends only using one brew head at a time as multi use will reduce overall pressure on each group due to only 1 pump. (same as most machines)
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Synesso Hydra: Mark Barnett,
Hydra uses the 2 pipe water feed to separate bar pressure.
Stage 1: pre-infusion on inline pressure
Stage 2: even ramp up to 9 bar, taking a few seconds
Stage 3: Extraction at 9 bar
Stage 4 post-infusion on inline pressure
All stages have adjustable taps to change bar pressure.
The Hydra has an electrical switch assembly not mechanical so group head requires no maintenance!
Volumetric is programable to run these pressure settings and stop shot.
Paddle groups can be programed to have first 3 stages programed (you push paddle all the way across) and the ability to start post-infusion when ever you like, by swinging paddle back to stage 1, then off.
Paddles prefer gentle use also, but won’t damage internal parts if heavy handed.
Hydra has a pump per group designed for simultaneous group brewing- no pressure loss.
All these machines have similer modern tech- Saturated group head, PID temp controls, dual boiler etc
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Pressure profiling and pre-infusion has to be replicable every time to get flavour consistency, ie electronically controlled, This eliminates Slayer and MP. The EP has mechanical group which by all accounts needs regular servicing, but has great LM tradition of quality,
By all accounts full pressure profiling opens a can of worms, too many variables during changes of pressure. None the rockstarts of espresso I spoke with at SCAA had anything good to say about Pressure profiling relating to cafe service, but they agreed pre and post infusion has merits if it can be replicated every time.
René
The Cooling Tray Sessions 
