quantum. Coffee

Varlamov A., Balestrino J. The physics of coffee making // Kvant. - 2001. - No. 4. - S. 2-7.

By special agreement with the editorial board and the editors of the journal "Quantum"

A traveler wandering from one country to another may notice that in this age of standardization and the dominance of transnational monopolies, when the same soft drinks are served in New York and Kathmandu, the coffee market remains surprisingly colorful and diverse. A drink from the same coffee beans is prepared and drunk differently in Turkey and Egypt, in Italy and France, in Finland and the USA. Ordering coffee in a bar somewhere in Naples, you will get an elegant cup a little larger than a thimble, at the bottom of which a thick drop of almost black color slowly sways, covered with an appetizing foam. However, if you make the same order in Chicago, you will receive a half-liter plastic jar filled with brownish hot water. We do not undertake to judge which of the drinks is tastier or healthier, but simply discuss the various methods of making coffee and the physical processes associated with them.

boiled coffee

This is one of the oldest ways of preparing a coffee drink, which has survived to this day in the north of Scandinavia. Roasted and coarsely ground coffee is poured into water in the amount of 10 grams per 150-190 milliliters of water and boiled in a coffee pot for about 10 minutes. Then the drink is poured without filtration into cups and settled for several minutes. There is no interesting physics in this process, and the authors refrain from commenting on the taste of this drink.

Paper filter coffee maker

Such a coffee maker is widespread in the USA, in northern Europe, in Germany and in France. Its principle of operation is extremely simple, and the process of making coffee takes 6-8 minutes. Coarse ground coffee is poured into a conical filter made of special filter paper. Further, hot water drips onto the ground coffee, “washes” it, seeps through the filter and is collected in a glass vessel. The result is a light coffee drink: only a few coffee oils seep through the dense paper filter, and coarse grinding and lack of excess pressure do not contribute to the complete extraction of all coffee aromas. The American dose is 5-6 g of coffee per 150-190 ml of water, the European one is 10 g per cup.

"Turkish coffee"

The description of the process of making such coffee is already worthy of attention. Coffee beans are ground into dust (fine grinding), and this powder, often along with sugar, is poured into a metal (usually copper or brass) cone-shaped coffee maker called a cezve. Then it is poured with cold water and immersed up to the very neck in hot sand (according to a different recipe, ground coffee is placed on the surface of already hot water). The heating of the liquid occurs due to heat transfer from the sand through the bottom and side walls of the cezve. In the absence of sand, you can use the low fire of a gas stove, electric stove, etc. As a result of the heating of the bottom layers, convection currents arise: the hot liquid carries coffee particles up to the surface, where, due to surface tension forces, they linger and form a “coffee crust”. Gradually, the contents of the cezve are brought to a boil: bubbles break through the crust, foam forms. At this point, the cezve is removed from the sand (or removed from the stove), as boiling "kills" the coffee. The procedure for bringing the drink to a boil is repeated two more times, which leads to the formation of abundant foam. The resulting liquid is poured into small cups and wait until the sediment goes to the bottom. The result is a delicious thick drink, especially if the amount of water was relatively small.

The disadvantage of this method is the presence of a suspension of coffee powder in the resulting drink, which gradually settles to the bottom of the cup. There is even a way of divination on "coffee grounds".

Italian mocha

One of the most common coffee makers for home brewing coffee in Italy is the mocha. It consists of three parts: a lower truncated cone (heater), where water is poured, a metal filter, where medium-ground coffee is poured, and, finally, an upper truncated cone, where the finished drink accumulates. This coffee maker is designed to prepare a drink of a certain consistency: water should be poured up to the level of the valve in the heater, the filter is filled up full - about 6 g per serving in 50 ml of water.

The process of making coffee in mocha is very entertaining. Coffee powder is poured into the filter and compacted, water is poured into the lower part of the mocha. Mocha is tightly twisted along the thread connecting the upper and lower cones. (The upper strainer covers the filter cylinder. Additional insulation from the external environment is a rubber gasket laid between the upper and lower cones.) The coffee maker is placed on a low fire. The preparation process consists in bringing water to a boil in the heater, then running it through coffee powder, further lifting the drink prepared in this way through the tube and draining it into the volume of the upper cone. After that, the coffee is ready for pouring (through the spout) into cups.

Everything seems simple and clear. But what is the “driver” of the described process? Of course, fire. First, the water is heated to a boil, then the process of boiling begins in a closed volume, where the water is given much more space than the steam above its surface. The temperature passes through 100 °C, the steam above the water surface always remains saturated, its pressure exceeds 1 atm and continues to grow. The external pressure, up to the upper level of the filter, is equal to atmospheric. Saturated steam with a temperature above 100 ° C begins to play the role of a compressed spring, pushing slightly superheated boiling water through the coffee powder contained in the filter. At the same time, all those aromas, oils and other components that turn water into a wonderful drink are extracted from coffee. It is clear that the properties of this drink depend both on the coffee powder itself, which is in the filter, and on the temperature of the water and the time it flows through the filter. The secrets of preparing a mixture of coffee beans, their roasting and grinding are the secrets of each manufacturer, based on talent, work and centuries of experience. What determines the time of liquid flow through the filter, we can understand without industrial espionage, based only on the laws of physics.

In the middle of the nineteenth century, French engineers A. Darcy and J. Dupuy made the first experimental observations of the movement of water in pipes filled with sand. These studies laid the foundation for the creation of the theory of filtration, which today is successfully used to describe the movement of liquids, gases and their mixtures through solids containing interconnected pores or cracks. In addition to creating the first perfect water supply system in Europe in the city of Dijon, Darcy formulated the so-called linear filtration law, which today bears his name. It relates the volumetric flow rate of the liquid Q through a sand filter whose length L, and the area S, with water level difference Δ H above the filter and at its base:

\(~Q = \frac(k_f S \Delta H)(L)\) .

The filtration coefficient included in this formula k f depends both on the nature of the porous medium and on the properties of the flowing liquid. These properties can be easily separated:

\(~k_f = \frac(k \rho g)(\eta)\) .

at the same time passing from the level difference characterizing a specific filter to the pressure difference on both sides Δ R = ρqΔ H:

\(~w = \frac(k)(\eta) \frac(\Delta p)(L)\) .

Here \(~w = \frac QS\) is the so-called filtration rate, which shows how much liquid flows through a unit area of the filter surface per unit time, the coefficient η characterizes the viscosity of the liquid, and the coefficient k is a characteristic of only a porous medium and is called the permeability coefficient (it has the dimension of area). It should be noted that permeability, expressed in SI units, is usually very small. So, for coarse sandstones it is 10 -12 - 10 -13 m 2, for tight sandstones 10 -14 m 2. In the oil field, a special unit is used for the permeability coefficient - darcy (D): 1D = 1.02 10 -12 m 2.

Let's try to apply Darcy's law to the study of our mocha. For example, it is interesting to know to what temperature the boiling water at the bottom of the coffee maker overheats. Let us estimate the pressure difference between the lower and upper sides of the filter using the Darcy formula:

\(~\Delta p = \frac(w \eta L)(k) = \frac(m \eta L)(S \rho kt)\) .

The characteristic dimensions of the filter for mocha for three servings are as follows: L= 1 cm and S= 50 cm 2; mass of coffee m= 150 g runs over t= 3 min. We can take the permeability coefficient of the same order as for coarse sandstone: k≈ 10 -13 m 2. Density of water ρ \u003d 10 3 kg / m 3. One must be careful with viscosity, as it is highly dependent on temperature; nevertheless, in tables of physical quantities one can find that η (100 ° C) \u003d 10 -3 Pa s. As a result, we get Δ R~ 10 4 Pa. The corresponding boiling point of water, according to the well-known plot of saturation vapor pressure versus boiling point, is T* = 105 °C.

So, we figured out the normal process of making coffee in an Italian mocha. However, there are grim rumors that at times these coffee makers go rogue and turn into bombs, threatening kitchen ceilings and walls, not to mention coffee drinkers nearby. Why and how can this happen?

It is clear that, first of all, the emergency valve, made in the lower part of the mocha, can become clogged or oxidized precisely in order to release steam in case of unplanned overheating. Therefore, old coffee makers become dangerous. The second reason for the "catastrophe" may be the obstruction of the filter itself, filled with coffee powder. There may be various reasons for this. The most exotic, in the spirit of a detective about the life of the Neapolitan mafia: a sophisticated killer clogged the upper tube with drunk coffee left in an unwashed coffee maker from yesterday. More realistic is this: densely packed (unknowingly to make it stronger) coffee powder too finely ground for mocha becomes impervious to water. Under the action of continued heating, the pressure in the lower vessel will grow unacceptably high, the water will break through a channel in the filter and tear the top of the coffee maker off the thread. What is the reason for such impermeability of the filter?

It turns out that the whole point is the limited applicability of Darcy's law. Indeed, the linear law of filtration is written without taking into account capillary phenomena. A porous medium can be represented as a complex system of interconnected voids and capillaries. A liquid can flow through a capillary with a radius r only when the pressure difference at the ends of the capillary exceeds \(~\frac(2\sigma)(r)\), where σ - coefficient of surface tension. The pressure difference at the ends of the capillary can be estimated as \(~\frac(\Delta p)(N)\), where Δ R is the pressure difference across the filter, and N- the average number of capillaries that fit on the thickness of the filter. Take for evaluation N~ 10, ∆ R~ 10 4 Pa, σ = 0.07 N/m. We obtain that already at the average capillary radius r~ 0.1 mm, some of them may be blocked for the flow of liquid at a normal pressure difference across the filter.

At first glance, there is nothing wrong with this - after all, some of the capillary pores will turn out to be of a larger radius and will be able to pass liquid. However, a closer analysis shows that this may not be enough. It is necessary to require that the fraction of open pores be greater than some critical value. Otherwise, the open pore system will not permeate the filter from one boundary to the other; moving through these pores, we can only take a few steps and inevitably run into an impenetrable capillary. It is said that in this case the system of open pores lost its “connectivity” and ceased to permeate the entire space, it was split into many small groups of pores connected to each other (such groups are called clusters).

The properties of systems with broken or limited connectivity are studied by a special section of statistical physics called percolation theory (from percolation- leakage). The critical concentration (share) of elements at which the system loses connectivity is called the percolation threshold. The theory of percolation studies not only the conditions for stopping the flow (current, fluid) through the system, but also the properties of the so-called weak flow, i.e. just above the percolation threshold (when the flow goes through a small number of through capillary passages). It turns out that the dependence of the flow rate on the concentration of free pores (which in our case depends on pressure) has a complex power-law character (with a fractional exponent), i.e. is not at all like Darcy's law, which comes into force only when the flow occurs through a developed system of permeable pores.

But back to our coffee filter. In this case, the proportion of permeable pores depends on the pressure difference across the filter and on the average pore radius, which, in turn, depends on the degree of coffee grinding. With excessive grinding of the powder, the average pore radius decreases, and their number on the filter thickness increases; as a result, the system may be impermeable up to a threshold pressure difference of several atmospheres. And then the following may happen. In a filter compressed by excess pressure, the average pore radius will decrease even more, which will lead to an increase in the threshold pressure difference, and this will further press the coffee in the filter ... In short, a vicious vicious circle is formed: the temperature in the lower vessel will increase, along with her pressure will rise. Finally, at a certain pressure, the water will nevertheless break through a channel for itself and break through the filter. At best, you will get bad coffee - after all, only a small part of the powder was used, and the temperature is too high. At worst, the pressure will rise so much that the thread will not withstand, and the coffee maker will explode.

Let's estimate the maximum (theoretical) damage that a mocha can cause by turning into a heat bomb. We will proceed from the worst: everything that could become clogged is clogged, and 150 g of water are heated in a closed volume, not much larger than the volume of the water itself. At a temperature of the order of critical (where the vapor density is compared with the density of water), which for water is equal to T k \u003d 373 ° С \u003d 646 K, all water will turn into steam. Further heating is possible, but the mocha itself will begin to glow - this has never been seen before. So, for the marginal estimate, let us assume that the corked mocha is heated to a temperature of the order T= 600 K. Having written the Mendeleev-Clapeyron equation, one can easily estimate the pressure in the lower part:

\(~p = \frac mM \frac(RT)(V)\) .

Assuming m= 150 g, V\u003d 200 cm 3, M= 18 g/mol, R\u003d 8.31 J / (mol K), we find that R~ 10 8 Pa \u003d 10 3 atm - this is a pressure of the order of the pressure at the bottom of the Mariana Trench. And the energy stored in a coffee maker at this temperature is an impressive \[~E = \frac 52 pV\] ~ 50 kJ, so the explosion would have dispersed individual parts of the mocha to speeds of the order of hundreds of meters per second.

From the above estimates, it is clear that the thread will not withstand much earlier. But the powerful force stored in the coffee maker due to excessive heat is also obvious: it is really more than enough to not only splash the entire kitchen with a failed drink, but also cause other troubles. So keep an eye on the valve, choose the right coffee grind, pour it into the filter without a slide and, most importantly, do not tamp.

Coffee in mocha is strong and aromatic, without sediment, but still inferior in taste to espresso coffee, which is served in a good bar. The main reason for this, apparently, is the relatively high temperature of boiling water forced through the filter by superheated steam. Therefore, the recipe for improving the quality of coffee when preparing it in mocha is as follows: put the coffee maker on a very low fire. In this case, the filtration process will be slower, however, the steam in the lower vessel will not overheat too much.

Probably, very good coffee can be made in a mocha, being in a mountain climbing shelter: there the external pressure is noticeably lower than 1 atm, and, for example, at the height of Everest, the water boils at 74 ° C - so overheating the water in the mocha will just bring the temperature to the optimum 90 - 95 °C.

Antique Neapolitan coffee maker "Napoletana"

This coffee maker resembles a mocha, but uses gravity filtration instead of pressurized steam filtration. It also consists of two vessels placed one on top of the other, and a filter filled with coffee between them. The water in the lower cylinder is brought to a boil, then the coffee maker is removed from the heat and turned over. Filtration occurs under the pressure of a water column of the order of several centimeters, so that Δ R does not exceed 0.01 atm. The process of making coffee here is noticeably slower than in mocha. We can experiment with making the same amount of coffee in both coffee makers and, based on the inverse proportionality of coffee brewing time to applied pressure, based on Darcy's law, check our previous estimate of the pressure in the mocha heater. However, in practice for "Napoletana" coffee is chosen with a coarser grind than for mocha, otherwise the drink will be ready only after half an hour and will turn out to be cold.

Connoisseurs say that coffee from Napoletana is tastier than from mocha: there is no detrimental effect of overheated boiling water on coffee.

However, the high pace of modern life does not leave time for a philosophical conversation on the terrace overlooking Vesuvius and the beautiful Gulf of Naples, in a pleasant expectation, when you finally get a cup of healthy drink. This luxury remained in old paintings from Neapolitan life and in the creations of Eduardo de Philippe.

"Espresso"

Not all Neapolitans were patient even in past times. They say that in the last century, one of those residents of the capital of the kingdom of the Two Sicilies, who could not calmly wait at Napoletana, convinced his friend, an engineer from Milan, to design a fundamentally new coffee maker that prepared an individual portion of a wonderful aromatic thick drink for half a minute.

Every cup of good coffee is a repository of the secrets of growing and harvesting coffee beans, preparing the mixture and roasting it, grinding... Behind the pinnacle of coffee art - a small cup of Italian "espresso" - there is also high technology. The espresso maker, which is also called espresso, is much larger and more impressive than its counterparts described above. Typically, such machines are found in bars and restaurants, but for connoisseurs and coffee lovers, there are also home versions of this machine. The company "La Pavoni", which has been producing such coffee makers since 1905, is one of the oldest, and its products are known all over the world.

In espresso, water with a temperature of 90 - 94 ° C is forced under a pressure of 9 - 16 atm through a filter with coffee powder of special grinding, even finer than for mocha. The whole process takes 15-25 seconds, resulting in 1 - 2 servings of coffee, 20 - 35 ml each - for you personally and maybe for your interlocutor. The process of liquid flowing through a filter with coffee powder is described by the same Darcy law as in mocha, however, the pressure difference applied to the filter is ten times greater here, and the temperature, on the contrary, is below 100 °C. These parameters are specially selected in such a way that the high temperature does not destroy the unstable fractions of the coffee drink. The relatively short time of interaction of water with the powder, together with high pressure, leaves everything superfluous in the powder and extracts all the best from it: coffee oil emulsions form the density of the drink, which cannot be achieved in any other way; its aroma is preserved by the presence of a foam that does not allow the volatile components to disappear. "Espresso", oddly enough, contains less caffeine - due to the short contact of water with the powder (20 - 30 seconds versus 4 - 5 minutes) in the filter and the smallness of its volume, all the caffeine does not have time to be extracted.

The first espresso was exhibited in Paris in 1855. In modern stationary devices that make up the equipment of bars and restaurants, water is supplied under the necessary pressure using a special pump available in the design. In a classic espresso machine, hot water from the heating cylinder, when the handle is raised, fills the chamber above the filter and is then pushed through the filter manually by lowering the handle; high pressure is created due to the dynamic resistance of the coffee filter and the effect of a lever that multiplies the force of the hand.

It is interesting to observe the behavior of the coffee stream flowing down from the spout as the cup is filled. At first, this jet flows well, then weakens and at some point turns into drops. The authors observed the same phenomenon in the mountains: the sun warmed the snow on the roof, and a stream of melt water flowed down the icicle either in a stream or a drop. Let's try to estimate the critical volume flow of water Q k , at which the mode change occurs. For simplicity, we will talk about the icicle, although the results will be applicable to the coffee maker.

Let the stream of water slowly flow down the icicle. It is clear that as long as the volume flow of water is very small, the jet will not work. Indeed, at the end of the icicle, water will collect into a drop, the drop will slowly grow, reach a certain critical size, break off ... and the process will repeat. Since we agreed that the water consumption is very small, the process can be considered almost static. Under equilibrium conditions, the detachment of a drop occurs when its gravity mg exceeds the surface tension force \(~F_(\sigma) = 2 \pi \sigma r\) acting along the perimeter along the constriction (we designated its radius r):

\(~mg = 2 \pi \sigma r\) .

The time of "filling" such a drop is obviously equal to

\(~t_k = \frac(m)(\rho Q_k)\) .

It is clear that the process of detachment of the drop also takes some time. The drop under the action of surface tension and gravity is almost in a state of equilibrium. But when its mass reaches a critical value and the surface tension can no longer compensate for the force of gravity, the bridge breaks. Typical jumper break time τ can be obtained from considerations of the theory of dimensions: a liquid with viscosity η must be moved a distance of the order r under the action of surface tension forces with a coefficient σ . Let's write the equation:

\(~\tau = r^(\alpha) \eta^(\beta) \sigma(\chi)\)

and compare the dimensions of the right and left sides:

C \u003d m α (kg / (m s)) β (kg / s 2) χ.

From here we get

\(~\begin(matrix) 1 = \beta - 2 \chi \\ 0 = \alpha - \beta \\ 0 = \beta + \chi \end(matrix)\) ,

\(~\alpha = \beta = -\chi = 1\) ,

\(~\tau = \frac(r \eta)(\sigma)\) .

Now it is clear that the change in the regimes of the droplet and the jet occurs at such a volumetric flow rate of water, when the next drop does not yet have time to come off, as a new one already runs, i.e. at

\(~t_k \sim \tau\) , or \(~\frac(m)(\rho Q_k) = \frac(r \eta)(\sigma)\).

Expressing the mass of a drop from the condition of its equilibrium in terms of the force of surface tension, we find the final beautiful formula:

\(~Q_k = \frac(2 \pi \sigma^2)(\eta \rho g)\) .

However, operating not with the volumetric flow rate of water, but with the mass flow rate, one could immediately obtain this formula from an analysis of the dimensions and the remark that Q k should not depend on the size of the icicle tip (the icicle melts and the tip “adjusts”). In the case of a metal spout of a coffee maker, its size, in principle, can affect the value of the critical flow, but not much, so the estimate found for the icicle is quite applicable to the spout of a coffee maker.

Instant coffee

The constant rush of modern life has led to the emergence of instant coffee. It is made from real coffee, which is ground and kept at high temperature and very low pressure. Water sublimates, and the remaining powder is placed in a vacuum package, where it can be stored for a very long time without losing its properties. Before use, it simply dissolves in hot water.

Variations on the theme "espresso"

With an espresso coffee maker and a good coffee blend, you can make a whole range of coffee drinks. So, in an Italian bar you can get: caffe'ristretto- "shortened coffee", made with a normal amount of coffee, but less water; caffe'lungo- "long coffee", prepared with a normal amount of coffee, but more water; caffe'machiato- the same "espresso", but with the addition of a small amount of milk; caffe'coretto- "espresso" with the addition of liquor, whiskey or vodka. Deserves special mention cappuccino” -“ espresso ”, poured into the bottom of a medium-sized cup and poured on top of milk, whipped with hot steam to a state of airy foam. A good bartender can pour this milk over coffee so that the first letter of your name written in brown on a white background appears on the surface. Or you can just sprinkle the snow-white foam with cocoa powder or chocolate chips.

Finally, they say that in Naples in some places they still serve caffe prepagato. It looks like this. A well-dressed signor comes in with a companion or a friend and orders: “Three coffees! Two for us and one caffe prepagato". After a while, a tramp or just a poor man walks into the same bar and asks if caffe prepagato. And the bartender pours him a free cup of fragrant espresso. Naples remains Naples...

The Neapolitan coffee recipe is nothing exceptional, but this drink is famous all over the world and is considered unique. It is not the recipe that makes it so, but the method of preparation. Neapolitan coffee cannot be made without a special coffee pot - a geyser coffee maker. Outwardly, it resembles two vessels connected to each other with a “layer” of a small container with filters into which coffee is placed. Passing through this container, the water is saturated with the taste and aroma of coffee. The result is a fairly strong drink with a delicate foam. It is served hot.

Technology Features

As already mentioned, the main thing in Neapolitan coffee is the way it is prepared, but there are other secrets. If you want to get a truly tasty, aromatic drink, it is advisable to take into account all the little things.

Any kind of coffee is suitable for making Neapolitan coffee, but not too finely ground. If the grind is very fine, coffee will fall into the main container, which will make drinking the finished drink not so pleasant. For this reason, medium grind coffee is preferred. However, many people prefer to use finely ground coffee, not being lazy to strain it later. This is also acceptable.
Coffee will have a richer flavor if ground before brewing and stored in beans.

A geyser coffee maker needs to be able to use it correctly:

Pour water into the lower container (without a spout) up to the mark (no more and no less, regardless of how many servings of the drink you want to brew).
Pour the powder into the coffee container. The container must be full, but it is impossible to strongly compact the coffee in it, otherwise the liquid will pass through it for too long. But if the coffee is not tamped at all, there may be no foam, this also does not hurt to take into account.
Screw on the top tightly. Your safety depends on the reliability of the fastening.
Put the coffee maker on the stove or turn it on if you have an electric one.
After the characteristic hiss tells you that the drink is ready, remove the coffee pot from the heat and turn it over, wait until the coffee is filtered (this takes up to 15 minutes), then pour it into cups. In some modern geyser coffee makers, there is no need to turn over, since the liquid enters the upper part and remains in it already during brewing.

It is advisable to pour coffee into warmed cups. This will allow him to stay hot longer and exude a charming fragrance.
The quality of the water is also important for the taste of the drink, and for the life of the coffee maker. Therefore, before cooking, it is desirable to soften the liquid, for example, by passing it through a special filter.

Neapolitan coffee is often made black, but cappuccino or latte are also possible. However, they can only be cooked in a device with a special valve. In any case, Neapolitan coffee is a very strong drink, it is undesirable to drink it for people with a tendency to hypertension.

Neapolitan coffee recipe

finely ground coffee (preferably for brewing in a cup) - 18 g;
medium grind coffee - 12 g;
softened water - 0.2 l.

Cooking method:

Fill the bottom of the coffee maker with water to the desired mark. The capacity of the tank may be different, if your coffee maker does not hold 200 ml, but more, then the amount of coffee should also be adjusted.
Mix approximately equal parts of fine and medium ground coffee (2 teaspoons each). Set aside a teaspoon of finely ground coffee for now.
Pour the blended coffee through a special tube into the container provided for it, lightly tamping.
Attach the coffee filter to the top of the water container.
Screw on the top tank tightly.
Turn on the appliance or put it on fire. After signaling that the drink is ready, turn the appliance upside down, if it is provided by the manufacturer (this information is contained in the instruction manual for your coffee maker).
Warm the cups and pour half a teaspoon of finely ground coffee into it.
Pour the prepared coffee into cups.

Serve Neapolitan coffee immediately after it has been made. It takes a long time to cook, and if not served immediately, it will turn out to be too cold and therefore less tasty.

If you want to make Neapolitan sweet coffee, the first small portion, about 20 ml, should be poured as soon as it is ready and whipped into foam with two tablespoons of sugar. This foam decorates the drink after it is poured into cups.

Neapolitan coffee almost always has a delicate foam, its rich taste and bright coffee aroma captivate. So do not be surprised that the method of preparing a drink, once used only in one place, is now known throughout the world.

For millions of Italians, coffee - be it espresso, macchiato, cappuccino, at home or in a bar, at breakfast or after a meal - is an inseparable companion every day.

History of coffee

Espresso / Shutterstock.com

The Italian word "caffè" comes from the Turkish "kahve", which, in turn, comes from the Arabic "qahwa". The first variety of the plant whose beans were used to make a drink was Coffea arabica (Arabian coffee tree); today, along with it, Coffea robusta (Robusta coffee) is also used.

The Italian gastronome Pellegrino Artusi, in his famous work The Science of Nutrition and the Art of Cooking Delicious Food (1891), argued that the best coffee is made in the Yemeni city of Mocha, so that it was Yemen that began to be considered the place of origin of the coffee tree. From Arabia, the custom of drinking coffee quickly spread to Egypt and the Ottoman Empire, and then to Italy, through the mediation of the merchants of the Venetian Republic.

Venice, Piazza San Marco. Cafe Florian, one of the first in the world

The first Italian coffee house opened in 1683 in Venice, on Piazza San Marco, and a century later there were more than two hundred such establishments throughout the country. Some - they were called "Philosophical coffee houses" - acquired an intellectual component: outstanding thinkers and philosophers gathered there.

However, very soon, coffee fashion spread from Italy to the rest of Europe, as well as America, and establishments called "cafes" or "coffee houses" began to appear in many countries, where intellectuals and wealthy representatives of the bourgeoisie often gathered. So now it seems hard to imagine that at first many Europeans did not particularly like the new oriental product: in Italy, for example, this Muslim drink caused some rejection. The situation changed only in 1600, when Pope Clement VIII declared coffee suitable for Christian consumption.

Naples and coffee

© winehistory.it

"Let's have some coffee!" This is the most frequent sentence that can be heard throughout Italy. But it is especially popular in Naples, where the tradition of espresso has taken root, which has become a real ritual, which is observed every day, in free time or at work.

Coffee was brought to Naples by Maria Carolina of Austria: having married King Ferdinand IV in 1768, she brought a widespread Viennese custom with her to the city.

The most important milestone in the history of Neapolitan coffee was the invention in 1819 of the so-called "cuccumella" (cuccumella) - a Neapolitan coffee pot, which, thanks to a double filter system, made it possible to alternate the Turkish method of preparation (brewing) with the Venetian (infusion). With such a coffee maker, it became possible to prepare coffee at home; in the 20th century, when the Neapolitans successfully mastered the bar coffee machine for espresso (invented in Turin in 1884), the cuccumella was replaced by a more modern version - the moka.

Recipe for the perfect coffee

What is the secret of Neapolitan coffee? The real secret is in the Neapolitan coffee blend and its special roasting, which gives the beans a slightly darker color than in other regions of Italy and the world. A couple of days after such roasting, the essential oils contained in the beans are felt much brighter, and the beans themselves give the drink their aroma better.

Naples has a lot of tales and traditions associated with coffee. One of the most common - the tradition of "hanging coffee" - testifies to the generous nature of the locals. Its essence is that a person, entering a bar, pays immediately for two cups of coffee: he drinks one himself, while the second is intended for anyone who asks.

Cafe Gambrinus

© winehistory.it

Gran Caffè Gambrinus is an old Neapolitan cafe on via Chiaia. It is named after the legendary king of Flanders Gambrinus, who is considered the inventor of beer. "Gran Caffè Gambrinus" is one of the first ten cafes in Italy and is part of the national association of vintage cafes.

© slowitaly.yourguidetoitaly.com

The English writer Oscar Wilde used to visit this cafe. And in the era of fascism, its importance in public life was so great that Gambrinus, along with other institutions popular among left-wing intellectuals, were completely closed. Today, the coffee and pastries here are just as delicious as they were in the old days, and the setting retains its lovely ambiance.

Step 1: Grind the coffee beans.

One of the secrets of making this amazing coffee. This is a special apparatus - a coffee maker, which consists of two vessels, between which there is 2 grids - filters, where finely ground Neapolitan coffee is poured and, unfortunately, without this device, it is impossible to brew real Neapolitan coffee. But do not be discouraged, such a coffee maker can be bought in supermarkets and online stores.

To get started, take a package of real Neapolitan coffee and open it with scissors. Take a bean grinder and grind the beans to a powder.

And the second secret, in order for coffee to be a success, grind coffee through a coffee grinder twice, first the grains and then the resulting mass.

Step 2: Prepare the Neapolitan coffee cup.

Take a cup with thick walls. Why thick walls? Because coffee in such a cup will cool down more slowly, and you will be able to stretch your pleasure from drinking it. And 1 more secret - dial half a teaspoon fresh, freshly ground coffee and pour it into a clean, dry cup.

Step 3: Brew coffee.

Separate the two halves of the coffee pot, the bottom without the spout from the bottom with the spout. Pull out the filter. Unscrew the filter cap and pour into it 2 tablespoons fresh finely ground coffee and close the filter cover. Pour into bottom cup without spout 200 milliliters of water. Do not fill the bowl above the level of the vent hole! Place the filter back into the container filled with water. Screw the bowl with the spout onto the bowl filled with water. In this case, the nose should look down. Turn on the stove to a strong level and set the coffee maker on it. Bring the water to a boil, when it boils, you will hear it by the characteristic gurgling sound. Remove the coffee maker from the stove. As soon as the steam comes down from the vent, and this will happen after about 30 - 40 seconds, turn the coffee maker upside down and let the coffee pass through the filters, drop by drop, for 7 - 10 minutes. Remove the top block and pour yourself a cup of aromatic coffee through a sieve. The raw coffee that remains at the bottom of the cup will rise up, stir the resulting aromatic mass with a teaspoon and wait 1 moment, until fresh coffee settles to the bottom of the cup. The fresh aroma of brewed coffee and a light but quite perceptible aroma of freshly ground coffee combine and you will feel an indescribable fan of smells of real Neapolitan coffee.

Step 4: serve Neapolitan coffee.

Neapolitan coffee served hot. It is poured into thick-walled cups so that it retains its temperature and can be infused for 1 minute with fresh ground Neapolitan coffee beans. This type of coffee is served without sugar. Jam, sugar, crackers, or whatever is sweet, are placed separately in plates or vases. A pleasant drink for the morning time of the day to cheer up and fill up with strength. Bon appetit!

- − Sometimes for those who like it sweeter, sugar is allowed in Neapolitan coffee, but it is not put in a cup of coffee after the drink is prepared. Sugar is poured into a bowl with water, brought to a boil and passed through coffee filters. It makes a very sweet and delicious coffee.

- − In order to brew Neapolitan coffee, you do not have to use Neapolitan coffee. In the presence of a Neapolitan coffee maker, this drink can be brewed with any very high-quality type of coffee.

- - Do not change the above recipe while preparing this type of coffee, as you may get either too bitter or too bland, not brewed.

- − Why should coffee be filtered after it has been brewed? This process is necessary so that there is less unnecessary sediment in the cup. The old boiled coffee is removed and the broth itself is poured into the bowl, it is infused for 1 minute with fresh ground coffee, which eventually settles as sediment at the bottom of the cup, but at the same time gives freshness and astringent aroma of coffee beans.

01.04.2013 11:30

I have seen the image of this coffee maker countless times on the Internet. But fate somehow did not push me with her in reality ...

« Caffetiera Napoletana". Behind it is a whole layer of culture of the bright and distinctive southern Italian region of the province of Campania - Naples.

"New City" Neapolis or elegant-sounding in the local dialect as"Napule" is a region with a full-fledged coffee history worthy of a separate book. I will return to this wonderful city in my stories, and today - a story about a GREAT, but almost gone coffee maker - "Caffetiera Napoletana".

This Neapolitan lady is not from these parts. In fact, she is French. Yes, yes, it was there that its prototype was born almost two centuries ago, and it was called the “French filter coffee maker” (“Caffettiera Francese a filtro”), sometimes adding the definition of “two-story” (“a due piani”).

How this French creation got to Naples is not known for certain, but since the influence of the French kings has always been strong in these parts (since the time of the Sicilian kingdom), in general, there is nothing surprising in such assimilation.

In the Neapolitan dialect (now increasingly referred to as the "Neapolitan language"), this coffee maker is called " cuccuma" or " cuccumella". There is a claim that it comes from the Latin word "cucumis" - "cucumber" - after the elongated shape of the coffee maker.

I don’t know, but I think that this is no longer so important, because 9 out of every 10 Neapolitans I interviewed (and in total I “tormented” 30-35 people on this topic) could not remember« what is the name of the traditional Neapolitan coffee maker?» - even when I showed the purchased for yourself here in Naples "kukumu" ...

Moreover, every third after the words " traditional Neapolitan coffee maker"tried to show me moka (most often - Bialetti), being in full confidence that this is the famous" caffetiera Napoletana ". Oops...

Here, with sadness (or maybe not with sadness), we must admit that in Neapolitan houses, where mocha Bialetti began to penetrate from the second half of the last century, the latter won an almost unconditional victory. Moreover, Neapolitans (like many Italians in general) believe that only Bialetti can be a moka - the image of this brand is so strong...

There are reasons for this - traditional moka is more convenient in almost all aspects, but there is such a thing as TRADITION. It is thanks to her that the "Neapolitan" is still alive. Although memories of her are becoming more and more the lot of older generations.

An important note should be made here: THERE IS NO 'moka Napoletana'! Should I say or just moka"(as an option -" moka Italiana ")- If is it about moka, or " Napoletana" (as an option- "Caffettiera Napoletana")- if it concerns the heroine of our story. Because sometimes in notes I meet such« mixture» - this is both terminologically incorrect and culturally incorrect.

The very first Napolitan taxi driver told me the difference between using a "moki" house and a "napoletana" house. I will not venture to judge the authenticity of the statement below, but a few more times I heard similar characteristics from Neapolitans.

Virtually every family that has a caffettiera Napoletana also has a moka.

The taxi driver mentioned above defined the purposes of their use as follows: “In moka we make coffee when we want to make a small amount of coffee - just for ourselves or a maximum - for ourselves and one more person. And from “napoletana” - when a company comes, or just when a lot of people drink coffee.

But, for example, my wife, who drinks 7-8 cups of coffee a day, prepares it from “napoletana” just for herself. And since “Napoletana” is usually large, she prepares a full coffee maker, pours some of it for herself, sugars and drinks, and leaves the rest and drinks it right cold a little during the day ”(here I note that other narrators still reheat this coffee, although they prepare it in exactly the same way "in reserve").

I have certain doubts that my readers will prepare coffee from "napoletana", but still I will tell you about the method of making coffee in it. There are a couple of colorful moments here that are not inherent in other coffee makers.

Again, in fact, "napoletana" is one of the variations of filter coffee makers and uses the physics of boiling water and gravity. By the way, inside the view Napoletana There are a huge number of subspecies of coffee makers.

So it consists"napoletana" of 5 components:

1. A container for water, which is filled with it to a small hole (usually it is recommended to fill in water half a centimeter below).

2. The coffee container is a kind of filter with holes for water to pass through it.

True, this is not quite a filter in its pure form, but rather- a certain cylinder with a filter in the upper part ...

Which is inserted into the water tank.

3. Top filter cover- with a thread - it is wound on top and closes the structure.

4. Top- she is at the bottom of my photo- with spout (this is due to the specifics of turning the coffee maker over during preparation, but more on that- below)).

5. I said items- five, but The 5th element can be called a regular lid, which is covered with ready-made coffee in the part of the coffee maker in which it will be after preparation.

Grinding for “napoletana” is used very fine (this is interesting, because for ordinary filter coffee makers, which essentially have the same principle of operation, coarse grinding is needed).

Coffee is poured into the filter with a slide, and, as in the case of moka, it is not rammed.

Caffettiera Napoletana comes in a variety of sizes, and again, as with moka, the size here is "per number of cups".

So, water is poured into the bottom of the coffee maker, coffee is poured into the filter, the design is assembledand put on fire.

A characteristic feature here is that "napoletana" is put as if« upside down» : the spout of the coffee maker looks down (at the end of preparation everything will fall into place), and both handles are aligned in one vertical line (this is necessary in order to make it easier to turn the coffee maker over later).

Coffee in "Napoletan" is prepared on a gentle fire - usually so that the flame does not go beyond the size of the bottom of the coffee maker.

After 4-5 minutes, the water begins to boil. Usually this moment is determined by ear (although a thin stream of steam from boiling water is sometimes visible visually).

The coffee maker is removed from the fire, and then immediately, firmly grasping it with both hands, very SHARPLY ( important!) flip,

At this point, a few drops of coffee may leak out of the hole in the water container - it's okay - this is normal.

And after that, the “napoletana” is placed on the table, waiting for the coffee to be filtered (water seeps through the coffee). This is the longest moment in the preparation - the coffee dripping time through the filter can last from 5 to 10 minutes...

It is interesting that a couple of people somehow vaguely mentioned that the water is boiled SEPARATELY and then just poured on top. I think you can do it that way, but it's too easy. And why then fence the whole structure? ..

Yes, one more important point: after the coffee maker is turned over - the Neapolitans often put a piece of paper folded into a cone and bent at the end at the end of it - so that the aromas do not come out of the coffee being prepared. It's interesting - we just PLUG the nose, and the Italians pack it tighter, believing that you can't lose even a milli-dose of aroma...

Such a cap is called "cuppetiello".

The episode with him was very spectacularly shown by the outstanding Neapolitan film actor Eduardo de Filippo in the comedy “Questi fantasmi” (“Ghosts”), when in the famous scene with coffee he sits on the balcony and most colorfully describes the poetry of the Neapolitan coffee maker, with “cuppetiello” on its spout.

I watched this episode ten times in a row, at least. And I watch it over and over from time to time. Because, my God, with what love de Filippo talks about making coffee! And in general, n and in my opinion, this scene is the BEST coffee scene in EVERYTHING of world cinema. I am 100% sure of this... Of course, to fully understand it, you need to know the Italian language and hear the Neapolitan specifics of speech, but even without this, the episode is permeated with love for coffee, which is impossible not to feel...

Apparently, this is because, as the Neapolitans say: “A che bellu cafe sol a napl o san fa!” - " Such fine coffee is made only in Naples!»

One Neapolitan guy told me that he remembers from childhood how his grandmother, when she made coffee for herself, gave him a piece of bread (crust) with a drop of coffee and a little sugar on it, and for many years it was a kind of lunch treat for him .. .

Well, where else can you find such memories? ..

And let "caffetiera Napoletana" require more fuss and time, and let her still lose to her relatives in the espresso line and even to her own sister-moke - I think that sheremained undefeated andstill doomed to immortality.

Because "Napoletana" is not a coffee maker, it is- HOLY RITUAL...

by Sergey Reminny. Coffee Expert. Coffee Blog