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The moka pot is a stove-top or electric coffee maker that brews coffee by passing hot water driven by vapor pressure and heat-driven gas expansion through ground coffee. Named after the city of Mokha, it was popularized by Italian people aluminum vendor Alfonso Bialetti and his son Renato starting from 1933. It quickly became one of the staples of Italian culture. Bialetti continues to produce the original model under the trade name "Moka Express".
Spreading from Italy, the moka pot is today most commonly used in Europe, Latin America, and Australia. It has become an iconic design, displayed in modern industrial art and including the Wolfsonian-FIU, the Cooper–Hewitt, National Design Museum, the Design Museum, the London Science Museum, The Smithsonian and the Museum of Modern Art. Moka pots come in different sizes, making from one to eighteen servings.
The original design and many current models are made from aluminium with Bakelite handles, though they are sometimes made out of stainless steel or other alloys. Some designs feature an upper half made of heat-resistant glass.
There are three major components in a typical moka pot:
When the lower chamber is almost empty, bubbles of steam mix with the upstreaming water, producing a characteristic gurgling noise—a signal that brewing should be stopped. Navarini et al. call this the "strombolian" phase of brewing, which allows a mixture of highly heated steam and water to pass through the coffee, which leads to rapid overextraction and introduction of undesirable flavors.
Unlike a standard percolator, the moka pot never sends brewed coffee back through the coffee grounds.
A number of physics papers were written between 2001 and 2009 utilizing the ideal gas and Darcy's laws, along with the temperature-dependent vapor pressure of water, to explain the moka pot's brewing process.*A. Varlamov and G. Balestrino, La fisica di un buon caffè , Il Nuovo Saggiatore: Bollettino della Società Italiana di Fisica 17(3-4) , 59–66 (2001)
Moka pots are sometimes referred to as stove-top espresso makers. However, a typical moka coffee is extracted at relatively low pressures of , while standards for espresso coffee specify a pressure of . Therefore, moka coffee is not considered to be an espresso. Typically, the moka pot uses a ratio of coffee to water, by mass, of approximately 1:10, resulting in a brew with approximately 3–4% dissolved solids. In comparison, espresso is "stronger" with 9–10% dissolved solids, and drip-brewed coffee is "weaker" with approximately 2% dissolved solids.
Samuel Parker, a coppersmith from Middlesex, England was granted a patent on January 11, 1833, for a tabletop machine which used a brewing method that sends self-pressurized hot water from a sealed vessel vertically through a bed of packed coffee grounds into a collector, as an improvement on the coffee percolator. Parker's "Steam Fountain" was sold starting in the 1840s, featuring a cylindrical body with two concentric vessels: an inner boiler and outer collector, topped by a glass dome which served to redirect the brewed coffee into the collector. It later became known as the "Vienna Incomparable". Similar steam pressure-driven devices were invented in Paris by Alexandre Lebrun (1838) and in Berlin by H. Eicke (1878).
Alfonso Bialetti popularized the machine for home use, initially marketing the Moka Express starting in 1933, but relatively few were sold until his son Renato embarked on a major marketing campaign after the latter took over the family business in the 1940s, including the commissioning of the company's iconic mascot, , in 1952. According to the company, the design of the original Moka Express has not changed since its debut. Bialetti Industries applied for a patent in 1946 describing an apparatus which uses the same brewing method but arranges the vessels side by side, rather than stacking them vertically.
Among the variations to the moka pot design that have been introduced since the 1930s are those that integrate an electric heating element in the boiler, expedite brew time, create milk froth, and allow microwave brewing.
To expedite brewing, a weighted valve called Cremavent has been added as a pressure regulator on top of the nozzle that allows pressure to build up inside the water tank in a manner similar to a pressure cooker. As pressure builds up more quickly in this method (since there is much less leakage of vapour) compared to the standard moka pot, it reaches the level required for water to rise through the ground coffee in a shorter time. The result is coffee brewed at a higher pressure and temperature than the standard pot, making it more similar to espresso and therefore with more visible crema.
Another variation (the Bialetti Mukka Express) allows for milk to be frothed and mixed with the coffee during brewing.
Moka coffee characteristics
Brewed coffee flavor, including that of a moka pot depends greatly on bean variety, roast level, fineness of grind, water profile, and the level of heat used.
Maintenance
Moka pots require periodic replacement of the rubber seal, a scouring of its removable filter, and a check that the safety release valve is not blocked. All parts of the pot should be scrubbed by hand using a mild detergent, as aluminium moka pots are not dishwasher safe. bialetti.co.nz thekitchn.com Running the pot through the dishwasher generally results in corrosion and oxidation of the protective oxidized layer of aluminium, leaving freshly exposed aluminium to react with the air, creating a dirty, reactive, and blackened surface.
Aluminium migration
The potential for toxic amounts of aluminium migration being created by brewing an acidic beverage in an aluminium pot have been scientifically investigated, and determined to be "negligible" – falling below 1% of recommended total weekly intake level once a new pot has been used. Summary: An initially low level of aluminium migration (of under 3% recommended total weekly intake (TWI)) occurs after the first use of a new pot, after which the level stabilizes below 1% TWI, decreasing with each observed use; migration after dishwasher cleaning increases to a maximum observed level of just under 4%, and thus dishwasher cleaning is strongly discouraged. Following the pot's stabilization at below 1% with regular use, migration rose to a maximum observed level of just under 4% after a dishwasher cleaning, resulting in dishwasher use being strongly discouraged.
History and variants
Pot sizes
Moka pots are sold in various sizes based on the number of demitasse cups they produce, measuring approximately per cup. The following table lists sizes for some popular Bialetti Moka pots:
+ Bialetti Moka pot sizes
! rowspan=2 Cup size
! colspan=4 Aluminum ("Moka Express" / Moka Induction / Brikka / Dama / Mini Express / Break)
! colspan=4 Stainless steel ("Venus" / "Musa" / "Kitty")
See also
Further reading
External links
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