Espresso machine

An espresso machine (usually Espresso Machines Coffee Machines are meant ) is generally a device for brewing espresso and other coffee specialties.

Principle of operation

In the espresso machine water is heated in a gas or electrically heated boiler or heat exchanger to about 90 ° C. and passed below about 9 bar pressure through finely ground espresso coffee. The pressure is generated either by a lever or an electric pump. Technically obsolete are systems in which the pressure is recovered by water vapor ( high temperature and low pressure) and a hydraulic device from the line pressure ( too high a water consumption).

A patent is pressed at the water using a piston at high pressure through ground coffee, Gaggia Achille had 1938 registered. According to legend, it was at first surprised that the extracted beverage to increase the pressure suddenly a frothy crown, called crema received. Dama Lige espresso drinkers were even so skeptical that machine manufacturer initially their espresso " with natural crema " (Italian:, con crema naturale ') praising so as not to be suspected of using chemical additives.

In order to prevent the ground coffee is swirled in the brewing chamber and the espresso so that would be weak, the coffee powder is called with a tamper, and coffee or espresso masher masher pressed. In fully automatic machines this is done by a stamp, at the same time the brewing water comes from.

History

Attempts to produce espresso with the machine, go back to the 19th century in general, have been patented as different designs. As a challenge was creating the necessary Drucks. As the inventor into force in Italy Angelo Moriondo, in 1884 a patent filed. Luigi Bezzera should have been shown at the World Exhibition in Paris in 1855 a prototype, but this could only market from 1901.

Since the 1950s, there were up to Italy but also in France and Spain, many smaller companies made ​​the espresso machine. The first German portafilter coffee machine for home use was the Aracati in the 1950s. The Italian units displaced equipment from other countries due to the better price -performance ratio.

Models

Professional espresso machines are typically used in coffee shops, although particularly in the to-go area ( gas stations, standing cafes ) are more likely found fully automatic machines, mainly because they can be operated without instruction. Machines for home use have come in recent years increasingly in vogue. We distinguish between the following construction:

Portafilter

(often semi-automatic ) sometimes work as professional catering equipment with a removable filter holder, which is filled with coffee grounds and fixed by means of a bayonet fitting in the instrument. You need to be supplemented with a separate coffee grinder, provided that the coffee should be freshly ground and the mill is built into the unit. In these machines, the operator can influence a variety of factors that are decisive for the quality of the result: the grinding degree, quantity, and amount of compression of the ground coffee in the filter holder and the duration of the brewing time. Thus it is possible with practice, optimally align the expiry on the quality of coffee used and to achieve a better result than with a fully automatic machine.

Most traditional espresso coffee machines work with an electric pump to generate pressure, but there are also models available that use a manually operable lever for it ( manual lever machines). Represents a technological breakthrough in 1961, the gaming Faema E61, which at that time new brew group, is even today used recognizable by their characteristic chrome, protruding from the brewing head unit in many espresso machines. The E61 has a built under the boiler spring loaded chamber for smoother pressure rise ( pre-infusion ), a controlled by eccentric valve, residual pressure derived after brewing in the drip tray and on machines with a heat exchanger, a thermosyphon, which keeps it hot at a standstill upside down and the water in the heat exchanger partially protects against overheating.

Many providers of smaller budget models offer traditional espresso coffee machines, the ( often called " crema valve " in English mostly " pressurized portafilter " or " pressurized baskets ") in the filter holder or the strainer, a pressure valve included; thus the water flow is released only when the pump has built up a pressure of less than 10 bar. Specifying 15 bar refers to the theoretical maximum pressure of the pump, which is only achieved if the water can not drain away. The correct brewing pressure is at about 9 bar, but set the bar for most household sewing machines to 12. This valve is used to produce a crema -like layer on the surface of coffee, even when using pre-ground coffee deposited or even without the need for the grind must be matched to the machine. This " crema " but is more of a coffee foam instead of a true emulsion of coffee oils, dissolves faster and has virtually no taste. Therefore, it is also often the talk of " fake crema ". The same technique can also be found in most household coffee machines.

Centrifuge machine

Not generate pressure, but have a small centrifuge, in which the ground coffee is, and which is flowed through by means of the centrifugal force from the heated water. This type of formulation has the advantage that the so -working machines very cheap to make and require very little maintenance.

These machines are enjoying in the lowest price segment a large popularity as they provide a decent quality espresso for very little money. Machines and high-quality espresso coffee machines are inevitably expensive because of the complex technology.

Coffee machines

Coffee machines can broadly apply to as " espresso machine", they allow more or less fully automatic espresso coffee at your fingertips. The ingredients Fresh apply above all to be very user-friendly. However, they allow only a very limited influence on the course of preparation and therefore the quality of the result. In many models, a coffee grinder is integrated, so that each portion is freshly ground and brewed, which is beneficial to the taste. In some devices, the brewing unit can be removed with little effort and cleaned, which is optimal in terms of hygiene. Other machines allow automatic cleaning and descaling, but are more prone to mildew, or other repair costs causing contamination may. In fully automatic coffee machine part, a high susceptibility and low durability in relation is criticized to the often high price. The quality of the fully automatic machines is more in the preparation of coffee cream or Schümli, a "real" espresso in the Italian style, however, can not these machines often (contrary to the representation in the self-promotion of the manufacturer) produce. This is due to the brewing unit of plastic that would not withstand the necessary brewing pressure, which is necessary for proper espresso preparation. Massive group heads made ​​of metal are found almost exclusively in gastronomic variations.

Outline professional espresso machines

The abbreviations for professional espresso machines differ from the usual for home espresso machines.

• Manual or piston espresso machines: For the typical piston engines are meant portafilter, which were common in the 1950s and 1960s. Here, the pressure is required for the extraction of the coffee, is applied by means of a piston and a long lever attached thereto. Many coffee lovers claim that this is the best type of espresso machine. Many manufacturers produce today (10/ 2007) of these machines, but only in small numbers.

• Semi-automatic machines: These are different from the reciprocating engines in that the pressure is applied here by an electrically driven pump ( diaphragm pump or volumetric pump). They have a single switch to operate with which this pump just on and off can be.

• Fully automatic: this is meant in the catering exclusively portafilter machines, which - in contrast to the semi-automatic - Measure the amount of water electronically and stop the pump by itself after a certain amount. The picture shows an example of a fully automatic M32 bistro with a brewing unit ( manufacturers: Cimbali ).

• Super fully automatic machines: These machines were not invented until the mid-1990s in the restaurant business. You can automate the entire espresso preparation and have one or more built-in grinders for different types of coffee. The complete process ( milling, pressing, extraction, Sud emit ) is fully automated at a touch. As the term " fully automatic " was already occupied, for this was going on automated equipment, the term " Super Fully automatic" marked.

• For several years, systems that automatically froth milk exist. This milk is drawn from a container, foamed by a steam jet with air, heated and passed via a line directly into the cup. This system ( cappuccino maker ) is found both in super automatic as well as in automatic and semi-automatic machines. The portafilter was reserved so far the Turbosteam system ( the company Cimbali ), in which the operator has to provide only a jug with cold milk under the special nozzle. By pressing a button, hot steam will shoot out of the boiler and compressed air from a compressor into the milk until a sensor detects exceeding a preset temperature. The foam thus produced is at the correct setting creamy, fine pored and better tempered than that of a cappuccino maker.

All these machines are still available in different group numbers (1 to 5). Subgroup is defined as a unit of heat exchanger, boiler group, strainer and filter holder ( and fully automatic dosing of a flow meter, electronics and control panel ).

For water heating, there are different systems:

• In the early days almost only Einkreissysteme were built, where the scalding water was taken from a cauldron. However, one has to make a compromise between brewing temperature and a sufficient volume of steam. (Household machines can be of a low brew temperature to a high temperature steam switch )
• Currently the most widespread are two circuit systems, in which in a cauldron (2-20 l ) of water is heated to about 120 ° C, controlled by means of the steam pressure by means of pressure switches. Because the tank is filled up to about two-thirds, formed with the resulting vapor pressure a water phase (bottom) and a vapor phase (top). Through lines here can be taken for foaming tea water and steam. Is let into the boiler per group, a heat exchanger, which can accommodate only a few hundred milliliters of water and through which the water of the associated brew group is headed. Thus for brewing only fresh water and no boiler water will be used.
• For several years, the dual boiler technology is on the rise. Here there is a large steam boiler and one or more small Brühkessel whose temperature is completely independent from the boiler and very consistent.
• Since boiler machines, the boiler must be 15-30 minutes in the preheated and home use espresso machine should not be left permanently switched on, Thermoblock Espresso machines are becoming increasingly popular. This eliminates the boiler, the water is heated directly in an electric water heater and promoted by vibration pump. Such espresso machines can already prepare two minutes after turning on espresso, but do not have Brühdrucksteuerung.

The heating of the boiler is usually electric. Many gastronomic two-circuit espresso coffee machines are also available with additional gas heating, which at low current connections such as can also be operated at beach bars alone or for faster heating up from cold along with the electric heating.