Until the 40s of the last century, the technology of making coffee was based on the passage of hot water through ground coffee with the help of pressure that was created with steam. This piston design was significantly improved by Achille Gaggia in 1948. The new model provided a more concentrated and flavorful coffee with a thick foam. This coffee was called espresso that is translated from Italian “under pressure.”
Improvement of coffee machines continued to develop actively. In 1961, the Faema E61 coffee machine was created. This prototype gained fame under the name Faema Legend.
This model first used a separate brewing group that is not connected to the boiler and remains warm due to the circulation of hot water. This heating system provided a constant water temperature that is ideal espresso making.
Cappuccino is an espresso option in English-speaking countries. The recipe for this coffee is based on the addition of milk, which is an old tradition in these countries. Today there are different methods of making milk foam.
Latte was invented in North America and is based on the addition of syrup.
The high popularity of coffee provided a high demand for coffee machines. Of course, the market reacted adequately and today offers a huge assortment of different devices. The abundance of proposals sometimes makes it difficult to choose the optimal model of coffee machine.. Of course, the price, functionality of the coffee machine and its technical characteristics are the main selection criteria.
Espresso models have a complex mechanism for water heating and pressurization. Water is heated up to optimum temperature in a boiler, is directed on dispensing group under pressure 15 bar and is passed through the ground coffee. The number of servings depends on the number of dispensers. Water is heated through wall of heat exchanger inside boiler up to 115-120 degrees with the help of electric heat elements. The high pressure prevents boiling. The boiler is made of steel or copper. Hot water is usually additionally used for cup heating.
Operation of heating elements is controlled with the help of thermo sensors for providing a constant temperature in the boiler. One-way valve provides a constant pressure in all groups.
This technology provides extraction degree up to 25%. For comparison, this value for other technologies is 15-18%. The duration of one cycle usually does not exceed 20-30 seconds.
Creating high pressure.
Espresso coffee makers are divided by principle of pressurizing on Steam-Espresso and Pump-Espresso.
Steam-Espresso models provide necessary pressure with the help of steam during boiling water.
They are well suited for coffee making up to 4 cups.
Pump-Espresso devices provide the operating pressure by means of a special pump.
Such method is more economical. It provides a more high quality beverage and a high speed of coffee making. But the cost of such models is higher.
Espresso coffee machines are subdivided by design on the carob, combined and automatic models.
Carob coffee machines are well suited for one or two espresso coffee cups. These devices have a special holder for ground coffee. Extraction efficiency and coffee taste essentially depend from the pre-pressing ground coffee. Therefore, coffee is carefully compacted. Optimal results are achieved at the exact according dimensions of pestle and holder. The relative complexity of a pre-pressing is disadvantage of such devices.
The material of holder also affects the palatability. Metallic holder provides good heating the coffee powder. In this case, the coffee has a thick lush foam and rich taste. Plastic is considerably less efficient due to low thermal conductivity. The low price and ease of use are the main advantages of such models.
Combined models consist of two parts that provides making coffee by traditional recipe with the help of drip method or making espresso coffee.
Versatility is their main advantage. But every part requires a separate care and various grinding coffee. The care complexity is their main drawback.
Automatic models provide automatic mode for espresso, cappuccino, latte, etc. The device self-grinds coffee beans, calculates the portions, delivers hot water or steam into the cup, dumps the residues into inner container and is cleaned at the end of the day. Full cycle of making coffee lasts only 30-40 seconds.
Such model always uses freshly ground coffee and do not requires the user to skills. The high cost and the need of periodic care (decalcification and cleaning coffee oils) are their disadvantages.
Modern models use ground coffee, coffee beans, coffee pods or coffee capsules.
The cost of the model without built-in grinder is minimal.
Models with built-in coffee grinder use the ground coffee and coffee beans.
Built-in coffee grinder is equipped with steel or ceramic millstones. Steel millstones are resistant to mechanical stress. But models with ceramic millstones work much quieter.
A wide range of coffees and the maximum preservation of its aroma and flavor are the main advantages of models with coffee grinder.
The high cost and the need of regular cleaning are the main drawbacks.
Coffee pods are the pressed ground coffee. It’s made as a single tablet weight of 7 grams (one serving).
The tablet is placed in filter paper. Coffee pods are designed for espresso. The coffee taste in such models depends only on coffee. Some models can use coffee pods and ground coffee.
Ease of use, economical expenditure of coffee, a convenient accounting its consumption, convenience and ease of cleaning are its main advantages.
The relatively limited assortment of coffees, lack of adjustment of coffee strength and relatively a high cost of one serving are the drawbacks.
Capsular models use special plastic capsules with tamped freshly ground coffee.
Such packaging reliably retains the taste and aroma of coffee.
During making coffee, the air jets pierce in capsule and stirred its contents. The used capsule is automatically ejected from the coffee machine. The coffee grounds are collected in a separate container. Accordingly, its volume affects the periodicity of its cleaning.
The compactness, convenience and ease of use are the advantages of capsules.
The high cost of one serving, the impossibility of using the ground coffee and a lack of unification for capsule sizes are their disadvantages.
But today these problems are partially solved. For example, the market offers compact devices for making capsules. The work of such a compact model is demonstrated on video.