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Espresso Coffee Cart and Barista Hire |
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HOME ESPRESSO MACHINES |
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There are three basic types of electric home-use espresso machines on the market, the electric steam, the electric piston, and the electric pump/boiler. The last kind, the electric pump has both thermo block and boiler sub-types. There are also sub-categories of semi-automatic, automatic, super-automatic. Electric Steam This electric steam espresso machine works by first pouring water into a reservoir. The water is then heated to boiling. This same water is used to steam milk and brew the espresso. This method results in water pressure up to about 1 bar (some manufacturers claim 3.5 bar), which is well short of the preferred pressure for brewing espresso of about 8 bar. Many people use an electric steam espresso machine in order to get a slightly stronger coffee. However, getting the consistent good crema (or any crema at all) characteristic of a well-made espresso is next to impossible on this type of machine. You will not get quality café-style results with this type of machine.
Electric Piston The electric piston type espresso machine is a cool looking machine and can actually be a lot of fun to use, although some people are so enamoured by their aesthetic appeal that they put them on shelf display. These machines are actually capable of producing a pressure of about 8 or 9 bar, which is the benchmark of a genuine espresso drink. Like the steam boiler model, the water reservoir heats up for milk frothing, and the unit is quite capable of producing a tight milk foam (microfoam), given the right foaming artist! The pressure for brewing espresso is achieved by pulling on a hand lever, which is attached to a piston. The piston then pushes water through a heating element, through the coffee grounds, and into a waiting cup.
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Pump The pump espresso machine has made things much easier for espresso lovers. Electric steam machines don't make enough crema, while electric piston machines are not easy to operate. This type of machine has a pump that pulls water from a reservoir and dumps it into a tank that heats the water. Two separate thermostats control brew temp and frothing temp. When a button is pressed, the pump activates and an espresso is pulled or milk is frothed. Some pump machines use a boiler to heat the water. However, a boiler can take up to ten minutes to heat up. A later innovation with pump machines was the introduction of a heating element (thermoblock) that heats the water in a matter of minutes. Today's pump machines with thermoblock usually take between thirty to fifty seconds to heat up. Sounds great doesn’t it, but while pump machines that use boilers may take ten minutes to heat up, thermoblock machines are not without their shortcomings. So let’s look at both types a little closer. Firstly you will often see marketing blurb for pump espresso machines claiming 9 bar, 13 bar, 15 bar, etc. So, what's the difference? In practice there is none. ALL the pumps used in domestic machines are vibration pumps, usually made by either ULKA (the most common) or Eaton, and they are all fundamentally the same. As long as the machine has a pump, you can ignore the "Bar" ratings. It’s the heating technology used in pump machines where fundamental differences, which profoundly affect espresso production, occur. Where "Thermo block" technology is used the water is heated in a multi channel metal block with an exterior element. The total volume of water inside the block at any time is small, no more than 10ml, and the theory is that heating the block via an external element and pushing the water through at a set flow rate will produce the correct water temperature. The problem with these machines is that in practice the first water touching the coffee is too hot and the rest of the water usually too cool. And, the flow restriction reduces the pressure at the group, making normal extraction difficult. It’s for this reason that ALL thermoblock espresso machines use "crema enhancing" devices of various types.
When steaming with thermoblock machines the pump pulses small bursts of
water into the overheated block, which is then supposed to flash into
steam. In practice steam production tends to be feeble and "wet". |
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Pump Espresso machines with boilers tend to have one of three types of boilers:
All 3 boiler types have sufficient water volume to keep reasonable temperature stability throughout a double shot. When heated to steam temperature, the limited volumes of the smaller boilers can mean slightly less steam time and power, but all have enough for average use. The larger volume boilers tend to have a faster "recovery time" between shots and that bit of extra steam, so that you can produce 6 cappuccinos in 5 minutes for your dinner party. The GROUP is the bit of the machine that the portafilter (the thing you load up with fresh coffee grinds) locks into, where the water is pumped through a "showerscreen" on to the coffee. All thermo block machines have aluminium groups with stainless steel shower screens. The smaller stainless steel boiler machines also have aluminium groups and stainless steel screens. Gaggias have a brass group with a stainless steel screen; Brass boiler machines have brass groups with stainless steel screens. Portafilters are another point of differentiation; with (again) thermoblock machines tending to have cheap aluminium portafilters and quality boiler machines chromed brass portafilters. Excellent espresso production relies on thermal stability of all the components in the process. Copper and brass are best, which is why you find them in commercial espresso machines.
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So what sort of machine do you need? For the home enthusiasts wishing to produce their own espresso drinks, the first consideration is "What sort of machine do I need?" The simple answer is "One with a pump." So called Steam Espresso units produce coffee that is similar to that from Moka/Espresso Pots; strong coffee but not espresso as it is currently defined. Only units with electric pumps or lever-operated compression can reach the 9 bar pressure level for true espresso. Pump espresso machines can vary in price from a few hundred to over 2000 dollars, depending on the materials used and the levels of gadgetry built into the machines, but it's important to recognise that a single group commercial machine can be purchased for less than a fully automatic home unit. In the long run, the commercial machine will make better espresso with far less maintenance than the automatic. The two largest manufacturers of domestic espresso machines are Saeco and Krups. In general, the Saeco machines in a given price bracket will outperform the similar Krups unit in terms of reliability and espresso quality. There are a number of smaller manufacturers with home units which are better than either Saeco or Krups, and often cheaper as well, and it's worth looking up internet reviews of domestic espresso machines at http://www.coffeeco.com.au/, http://www.coffeekid.com/ or http://www.coffeegeek.com/ before committing your cash. If I were shopping for a home espresso machine today I would be looking for one that includes a brass boiler, stainless steel body and professional standard portafilter, and a minimum of gadgets like "crema" and "froth" enhancers. Thermoblock Machine Update Most domestic coffee machines using thermoblock technology use just one thermoblock for heating using two thermostats – one for brewing and one for steaming – thus you can only brew or steam milk at any time – not both. However, in the latter part of 2005, Sunbeam released an espresso machine (the EM6900), with two thermoblocks – one dedicated to brewing and one dedicated to steaming.- thus allowing you to extract coffee and steam milk at the same time. You can read Alan Frew’s detailed review of this machine at http://www.coffeeco.com.au/articles/sunbeam.html. Alan rates the machine a 7/10. Personally, if I had the $700 or so needed to buy the Sunbeam EM6900 I would buy a Rancilio Silvia. The Silvia has been around for years – is a proven reliable performer – and produces a damn good espresso at home. After the Silvia, it’s a big leap in dollars to the next better machine ($1500+ RRP). And, if you want a Rolls Royce coffee machine that makes coffee to die for and a machine you’ll be able to pass on in your will, there’s always the ECM Giotto machine at $2550. PortafiltersThe portafilter is the part of the espresso machine that holds the coffee. When choosing a machine it is important that you know what kind of portafilter it has. There are three basic types, commercial, pressurized and pod. The first two accept ground coffee and the last works only with pods. There are also adapters for some machines - which convert the portafilter to another style. Understanding the differences between the portafilters will help you choose the right espresso machine. If it too hard to use, does not give you the control you need or is too limited in what coffee you can use; it will drastically affect the success you have with your espresso machine. True espresso is brewed at approximately 8 atmospheres of pressure. If you brew with less pressure your coffee will be weak and unsatisfying. If you brew with too much pressure the coffee will be bitter. So, play close attention as to how each type of portafilter functions and match that to your needs and expectations.
The commercial style portafilter is designed work like those used in commercial espresso machines used in cafes and restaurants. They are usually 58 millimetres in diameter (vs 53 mm for other types) and weigh up to 500 grams or more. They are usually made of chrome plated brass which is used for its' heat stability properties and durability. The greater diameter creates a larger surface area, which aids in the extraction process as well. This type is widely known for the excellent coffee that it can produce. At first, they can be finicky and difficult to operate. The reason for this is the critical nature of the pressure required to produce a proper espresso. In order to obtain this pressure the user must understand the steps in loading and packing the portafilter with coffee ready for extraction, which we will cover a little later. How do you know when the right pressure has been developed? By timing the shot. Use 30 lb tamp pressure and 7-8 grams of coffee and the extraction should take 20 to 30 seconds for 30 mls of espresso. With a little experience you will be able to tell by watching the pour. It will appear as golden-honey. The crema that forms in your cup will be a marbled foam that indicates you have achieved Java Heaven. So, the finer the grind and the harder you tamp the denser the coffee becomes and thus the greater the backpressure. Of course, the opposite holds true for a coarser grind and lighter tamp. A commercial style portafilter is commonly considered the gold standard for brewing the best espresso. The process can seem complex at first but it is really not difficult once you understand the process. You will find that this is the only portafilter available with the "Prosumer" models as well as lower priced espresso machines by Gaggia, Rancilio and FrancisFrancis. Pressurised Portafilter This type of portafilter creates the pressure for you. It’s not dependent on your tamping and grinding correctly. They have a device that will only allow the water to pass when the appropriate pressure has been developed. These systems were created to make it easier to obtain good coffee. Espresso is known for it's intense flavour, but many users came to think that it was nothing but bitter . Had they known how to make some simple adjustments they would have saved their pallet. To bypass this experience the pressurized portafilters were developed. Some use a valve and others use a special filter basket. The result is the same for both, proper pressure development and excellent espresso. You do not need to be as concerned for following the prescribed steps for extracting coffee. Just load the coffee grounds in the portafilter, give it a light tamp and go. Like the finicky commercial type handles the pressurized have their shortcomings. The pressurized portafilters are generally lightweight by comparison and normally run no larger then 53 mm in diameter. They are made of aluminium and plastic which are not as good at maintaining heat stability and the not as durable as the commercial types. It is also difficult to tell if you are getting the optimum results from the coffee. Where it is easy to tell with the commercial portafilter - you can tell simply by watching the espresso pour - the pressurized system has a tendency to mask these visual clues. Espresso machines with pressurized portafilters are: Saeco, La Pavoni (non-manual), Solis (uses a pressurized filter basket), Capresso & Krups Pod Portafilter Like the name implies, these portafilters are designed for Pods. What are pods? They allow you to escape the mess of ground coffee by pre-packaging the coffee into sealed filter paper. The coffee has already been ground and tamped (packed). All you do is place a single pod into the portafilter and lock into the espresso machine group. Turn on the pump and stop at the desired level. Remove the pod like you would a tea bag and you are done. The ground are all self contained. Seems really simple and it is. Pods made by Illy will work on FrancisFrancis machines as well as Saeco and Lavazza pods will fit as well. Pods come as single shot only and can run up to 4 times the cost of ground coffee. However, the quality is generally quite good, and little preparation knowledge is required, while clean up is the simplest of the semi-automatics. Other machines that are designed to accept pods are: Gaggia (with an optional pod adapter) & La Pavoni. The Solis machines will also work well with pods. Notwithstanding the benefits of pods, my personal opinion is that fresh ground coffee made in a commercial standard portafilter still produces better results. Adaptors
If you find that you
love one machine but it doesn't have the portafilter style you are looking
for. It is possible that it may have an adapter, or even an extra
portafilter. Many machine manufacturers recognized that consumers want
flexibility and designed ways to turn a commercial or pressurized into a
pod portafilter.
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