la marzocco Strada EP + CW 2 Group Espresso Machine Instruction Manual
- June 13, 2024
- la marzocco
Table of Contents
la marzocco Strada EP + CW 2 Group Espresso Machine
Product Information: La Marzocco Strada EP
The La Marzocco Strada EP is an espresso machine that allows for pressure profiling in coffee brewing. It offers advanced technology and features to enhance the brewing process and create a customized coffee experience. The Strada EP incorporates various brewing variables such as pressure, flow, temperature, and extraction time, which can be adjusted and controlled to achieve different flavors and characteristics in the final espresso. This machine is designed for professional use and is ideal for coffee shops, cafes, and other establishments that prioritize precision and consistency in their espresso preparation.
Product Usage Instructions
Introduction
The guidebook serves as a foundation for using and exploring the capabilities
of the La Marzocco Strada EP. It is recommended to use this guidebook in
conjunction with the La Marzocco Profile Editor, which provides additional
control over the brewing process.
Historic Espresso Technology
The guidebook provides an overview of the evolution of espresso machines,
including vertical boiler machines and piston lever machines. Understanding
the history of espresso technology helps in appreciating the advancements
offered by the Strada EP.
Grind
This section discusses the importance of grind size in espresso brewing. It
provides insights into the recommended grind settings for achieving desired
extraction results with the Strada EP.
Coffee Dose & Brew Ratio
This section explains the relationship between coffee dose and brew ratio in
espresso brewing. It provides guidance on selecting the appropriate dose and
brew ratio for different espresso styles using the Strada EP.
Temperature
The temperature plays a crucial role in espresso extraction. This section
covers the impact of temperature on flavor profiles and provides instructions
on setting and controlling the brewing temperature with the Strada EP.
Extraction Time
The extraction time greatly influences the flavors extracted from the coffee.
This section explains how to adjust and optimize extraction time using the
Strada EP for achieving desired taste profiles.
Pressure & Flow
Pressure and flow rate are essential variables in espresso brewing. This
section guides users on adjusting and monitoring pressure and flow using the
Strada EP to achieve specific flavor characteristics in the espresso.
Initial Stages of Extraction
This section delves into the early stages of espresso extraction, providing
insights into pre-infusion techniques and their impact on flavor extraction.
It explains how to utilize the Strada EP’s features to optimize the initial
stages of extraction.
The Golden Profile
The “Golden Profile” refers to an ideal espresso extraction profile. This
section discusses the key parameters and techniques required to achieve this
profile using the Strada EP.
Comparing Coffee Styles
This section explores different coffee styles and their unique
characteristics. It provides a comparative analysis of high solubility/low
density, medium solubility/medium density, and classic espresso styles.
Conclusion
The guidebook concludes by summarizing the insights gained from the previous
sections. It emphasizes the importance of experimentation and customization in
espresso brewing using the Strada EP. For more detailed information and
instructions, please refer to the complete user manual provided with your La
Marzocco Strada EP machine.
Introduction
This guide is designed to serve as a foundation as you begin to use and
explore the capabilities of the La Marzocco Strada EP, and pressure as a
variable in espresso coffee brewing.
This guide is dedicated to the baristas for which the machine is named: The La
Marzocco Street Team. The street team first assembled in April 2009. The
initial meeting involved 20 passionate professionals gathered in a conference
room during the Specialty Coffee Association of America’s Expo in Atlanta,
Georgia. After
a few hours of discussing the features and capabilities of the ultimate
espresso machine, the group had compiled a white board full of ideas that
would serve as the foundation for the development of the Strada EP. The Street
Team discussion continued in an online forum, and the membership continued to
grow. By the time the project was completed, over 300 baristas from around the
world had contributed input and feedback. The Strada is the physical
embodiment of what the Street Team came together to create. It is an espresso
machine designed by baristas for baristas.
Still, the Strada was designed to be a dynamic platform, flexible enough to
enable a barista to apply variable pressure in order to draw out the intended
flavor and texture of the coffee being prepared. To fully understand its
capabilities and how it might most effectively be employed, one must
understand how espresso technology started and how it has evolved over the
last century. The Strada is an espresso machine for the baristas of today, but
its story begins with the first espresso machines ever built.
Historic espresso technology
Vertical boiler machines
Vertical boiler machines were the first coffee machines made for espresso.
These machines were typically comprised of one, vertical boiler, which was
kept very hot (somewhere around 104c or 220f). The machine was heated using
either gas flame or charcoal, making the baristas job even more difficult. The
brewing temperature could also be manipulated by adding cold water through a
manual inlet valve.
When making espresso, the water moved through the coffee at 1.2 bars of
pressure. The dose of coffee depended on the manufacturer, and was anywhere
from 20 to 40 grams of coffee. The grind of the coffee was coarser than we see
today, and the extraction times averaged 60 seconds.
The resulting beverage was around 90 ml (3 oz.) in volume. The coffee was dark
in color. The body was thin, and flavors were of ash or burn. There was no
crema present on this coffee. The beverage was somewhere between brewed coffee
and espresso as we know it today.
Piston lever machines
The first lever machines were designed and created by Antonio Cremonese, who
was also the first to patent this design. However, the rights to the technology
were sold to Achille Gaggia in 1936 after Cremonese died.
Lever machines were the first espresso machines to produce crema. This was
foreign to coffee drinkers at the time and it initially was referred to as
foam or scum, which conjured something less than delicious. Gaggia, who was a
good salesman, began calling it “crema,” or custard, making it sound delicious
and desirable.
Piston lever machines were introduced as single boiler espresso machines. A
mercury pressure switch was used to control pressure of the boiler, giving
some automation to how these machines were managed. The brew temperature was
95-98c (203-208f).
In 1936 the coffee market was very unstable. With coffee prices on the rise,
these machines became popular because you could make espresso with less
coffee. The dose used for an extraction was 12-14 grams of coffee for a double
extraction. A double espresso was roughly 30 ml in volume.
Rotary vane pump machines
Most espresso machines being used today use a rotary vane pump to
pressurize the extraction. Initially, this technology was introduced to simply
make the barista’s job easier and more efficient. A mishandled lever machine
could be quite dangerous, as the lever could shoot back up if not engaged
properly. This led to many serious barista injuries. Using a rotary vane pump,
the barista could engage the extraction simply by pressing a switch.
The most common setting for espresso machines today is 9 bars of pressure. 9
bars has been chosen as the pressure, as 9 is roughly the mathematical average
of the pressure used with a lever machine.
The first of these machines was the Faema E61, named after a total eclipse
which occurred in Italy the same year (eclipse of 1961). Initial machine sales
were not very successful, as the pump pressure dramatically changed the way
the coffee tasted. It took roughly 10 years before coffee roasting was changed
to catch up to the technology of rotary vane pump espresso machines. However,
with time, this has become the most current way that we brew espresso coffee.
Strada ep technology
The Strada introduces three advanced components, never before seen on an
espresso machine.
Mechanical gear pump
Each group has its own mechanical gear pump, built into the espresso machine.
These pumps are incredibly reliable. The technology is adopted from
applications where reliability is essential, such as dialysis in medicine or
for hydraulic helicopters.
It is the gear pump that allows the barista to have full control of the
pressure being used to brew espresso.
Membrane potentiometer
Although each group head is controlled by a paddle, it is actually a membrane
potentiometer which activates the brewing of the espresso. This form of
electronic control is very similar to the click wheel of an early generation
iPod. On the iPod, you use your finger to trace the click wheel, allowing you
to navigate electronic menus. With the Strada, the paddle traces the
potentiometer, allowing the barista to control the Strada. Each group head and
steam wand have their own potentiometer for electronic operation.
Potentiometers are designed to have a very long lifespan and are rated for 100
million use cycles.
They also require no maintenance.
Electronic steam valve
The steam valves featured on the Strada EP are electronic, and do not
require any kind of rebuild. With proper maintenance and an annual cleaning of
the valve, these valves will have an incredibly long lifespan. It is this
electronic valve that gives the barista the ability to precise control of how
much steam is released from the boiler to the steam wand.
Brewing with the strada ep
Our experience & research
Creating the Strada EP was only the beginning. As we have seen throughout the
history of espresso coffee, changes in machine technology can create other
challenges in coffee brewing. As an espresso machine manufacturer, we want to
make sure the people using our machines are able to easily make delicious
espresso. For that reason, we wanted to learn as much as we could about using
variable pressure in espresso, so that we could be a resource to Strada EP
owners.
Our explorations started in February of 2011, when a group of two World
Barista Champions, two industry thought leaders, and two La Marzocco after-
sales managers gathered together in Italy. For three days, they dissected the
various stages of extraction, observing how pressure affected each one. Their
work laid a strong foundation for other team members around the world to
continue to build how they would use the Strada EP.
For this book, we compiled many of those methods and techniques and have laid
out a simple way for a new Strada EP user to be able to approach pressure
profiling.
Clear objectives
Unlike the espresso machines of the past, the Strada EP gives you total
control over pressure. This is very exciting, but can be equally intimidating.
Without an idea or objective in mind, it is easy to waste time and coffee
without achieving the desired outcome.
Here, we provide you with a starting point and a framework for exploring the
capabilities of variable pressure in espresso preparation.
Objective 1 – to brew espresso with flavor that reflects the experience of
cupping the same coffee.
Objective 2 – to brew espresso that tastes delicious and balanced, whether the
coffee has been roasted for espresso or not.
Identifying the variables
It’s important to consider all the parts of the espresso extraction process
that we have control of. A great barista understands how to manipulate each of
these variables to achieve optimum flavor of an espresso.
Grind
Coffee Dose & Brew Ratio Temperature
Extraction Time
Pressure & Flow
Grind
What we simply call grinding coffee, engineers refer to as comminution.
Comminution is essentially the reduction of a material into small particles or
fragments. We grind coffee into smaller fragments in order to increase the
amount of coffee bean surface that can interact with water and be extracted
during the brewing process. Comminution facilitates the transfer of soluble
and emulsify-able substances into the brew.
Grind, and grind adjustment, is one of the first variables we learn about in
becoming baristas. When we adjust the grind, we change the size of the surface
area that is available to make contact with water.
Coffee dose & brew ratio
Brewing quality espresso requires using the right amount of coffee. The right
amount of coffee can be determined by what basket is being used. La Marzocco
makes portafilter baskets in 7, 14, 17, and 21 gram sizes. For the best
extraction quality, we recommend using the listed dose, +/- 1.5 gram.
To get the most precise measure of finished espresso, it is recommended that
you use a scale to measure the beverage weight of an espresso. This is easily
done by placing a cup on a scale capable of measuring to .1 gram, and taring
it to 0. Extract an espresso into the cup and return it to the scale to see
your beverage weight.
Our brew ratio references the ratio of dry, ground coffee going into the
portafilter to the beverage weight of our finished espresso. 17 grams of dry
coffee packed into the portafilter brewed into an espresso that weights 34
grams is a ratio of 1:2. This resembles a traditional style of espresso.
Decreasing the ratio to a 1:1 (17 grams to 17 grams) is much closer to the
classic idea of a ristretto espresso. Increasing the ratio to 1:3 (17grams to
51 grams) resembles a lungo espresso.
Of all the variables, choosing the brew ratio can have the greatest overall
effect on the finished product. It greatly impacts all elements of the sensory
experience of the beverage.
Temperature
In the Strada EP, individual coffee boilers for each group head not only
contribute to greater temperature stability, but they also enable the barista
to set different temperatures for each group head. Each group head features an
LCD screen that displays the temperature of water flowing from the group to and
through the coffee.
Brew water temperature is important because it affects the efficiency with
which the water can extract the coffee. Water with a higher temperature has
more thermal energy, and therefore it creates a greater chemical reaction
within the coffee. A simple degree of change in brew temperature can
dramatically effect the flavor and body of an espresso.
Extraction time
Extraction time is the amount of time it takes to brew an espresso from the
moment the pump is engaged. Extraction time affects how much of the coffee is
being extracted. A faster extraction time means the water is passing through
the coffee at a higher rate, pulling less from the coffee, and leaving
desirable compounds behind. Slowing down the extraction increases the contact
time of the water with the coffee, increasing the number of compounds being
extracted from the coffee.
Pressure & flow
One key to understanding how to use the Strada EP is how pressure and flow are
connected. The data displayed on the Strada EP LCD screen refers to the
pressure reading at the coffee bed. When the portafilter is removed and the
pump is running, there is no resistance. Therefore, the display reads 0 bars.
Any other espresso machine will show 9 bars on the pressure gauge, even
without resistance. The difference is the place within the hydraulic system
where the pressure is being measured.
With the Strada EP, pressure and flow are directly connected. As pressure
increases, the flow of water in the group head increases so that pressure can
build. The Strada EP is designed to run the same pressure curve time and time
again.
What this means for you:
- If the dose or the grind of the coffee is changed, the resistance in the coffee bed is changed.
- If the resistance in the coffee is reduced, the Strada will increase flow to increase pressure, so the pressure curve is maintained.
- If the resistance in the coffee is increased, the Strada will decrease flow to decrease pressure.
- The change in flow to compensate for the change in resistance will increase or decrease the volume of espresso brewed by the pressure profile.
Initial stages of extraction
In researching the effect of pressure on brewing espresso, we decided to put
our initial focus on the first third of the extraction. This is the time when
the water begins to pour from the group and begins to interact with the
coffee. Water flowing from the group, but not at full pressure is called
preinfusion. There are a number of espresso machines that allow the barista to
control this.
Preinfusion, or a gradual increase of pressure and water applied to the
coffee, can positively impact the flavor and quality of extraction. If you have
ever cupped coffee, or brewed a French press or pour-over, you have probably
seen the chemical reaction of coffee meeting hot water. The coffee swells up,
so much so that some call this the blooming of the coffee. Preinfusion helps
achieve a similar result.
Using the Strada EP, we consider preinfusion to be the initial part of a
pressure curve where the pressure is below four bars. Longer preinfusion times
can make delicious coffee. However, it is important to be aware that
preinfusing the coffee for too long can make the coffee swell and bloom too
much, and may lead to channeling (where water passes through the coffee
without extracting).
Nonetheless, we found that using a gradual increase of pressure helps us to
repeatable brew tasty coffee.
The golden profile
Taking note of how preinfusion positively affects the brewing of espresso, the
pressure profile illustrated here shows a simple rise in pressure to a peak of
12 bars, then a gradual reduction in pressure over the second half of the
extraction. Our early research in exploring pressure profiling using the Strada
EP found this profile to consistently generate delicious coffee.
Comparing coffee styles
As the “Golden Profile” was tested over time, it became apparent that what was
initially considered
the perfect profile, was not necessarily the best fit for every coffee.
Further testing proved that the profile was least compatible with coffees of
medium and dark roast.
Comparing various roasts of coffee, you can see how light roasted coffee is
very dense, where dark roasted coffee is not. One way to see this clearly is
to weigh 10 grams of lightly roasted coffee and put it next 10 grams of dark
roasted coffee. Though the weight is the same, the volume of dark roasted
coffee will be much higher.
Not only is lightly roasted coffee more dense, but it is also less soluble.
Solubility is defined as the property of a solute (coffee) to dissolve into a
homogenous solution (espresso) with a solvent (water). In other words, less
soluble coffee is more difficult to extract than more highly soluble coffee.
Roast level is not the only cause of different densities in coffee. Much of
the variation can also come from where the coffee is grown, the variety
involved, and even the processing. There are many variables within the coffee
chain, and that is what makes coffee exciting and fun.
High solubility / low density
Recognizing the difference in various coffees, we decided to try cutting the
peak of pressure to six bars. We have found that this profile is great for
coffees with a higher solubility (dark-roasted or less-dense coffees). The
lower pressure seems to be gentler on the coffee, extracting the flavors we
want while minimizing the flavors that are less desirable.
Medium solubility / medium density
For coffees with medium characteristics, we find that peaking at 9 bars works
very well.
Classic espresso
As mentioned before, we focused on the two goals of brewing single origin
espresso that had flavor that reflected how a coffee cups. One might wonder then
what to expect with coffees roasted for espresso. Almost every espresso is
roasted and blended for traditional espresso machines. For these coffees, we
believe the profile below is best. It is built to extract coffee in a way that
is very similar to the La Marzocco Linea Classic.
In conclusion
The end of this book is only the beginning. The profiles here are a place to
start and a framework for you to begin experimenting with your coffee.
Once you have tried these profiles you can try variations such as moving the
peak point of pressure around in the extraction time. Peaking at 15 seconds
vs. 10 will alter the flavor. You might find this changes the taste balance and
brings out more sweet, bitter, or acidic qualities of the coffee.
Another variation to try is holding a peak of pressure rather than hitting the
peak and immediately ramping down. Holding at 6 bars for 5 seconds might pull
out some more interesting cup characteristics.
We encourage you to try different things and find what works best for you and
your coffee. Remember, the Strada EP is all about the barista. The machine is
simply a tool for you to unlock all the magical flavors of your coffee.
Thank you for joining us on this new adventure of coffee brewing.
-La Marzocco
References
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