Instant coffee
Encyclopedia
Instant coffee, also called soluble coffee and coffee powder, is a beverage derived from brewed coffee bean
Coffee bean
A coffee bean is a seed of a coffee plant. It is the pit inside the red or purple fruit often referred to as a cherry. Even though they are seeds, they are referred to as 'beans' because of their resemblance to true beans. The fruits - coffee cherries or coffee berries - most commonly contain two...

s. Instant coffee is commercially prepared by either freeze-drying or spray drying
Spray drying
Spray drying is a method of producing a dry powder from a liquid or slurry by rapidly drying with a hot gas. This is the preferred method of drying of many thermally-sensitive materials such as foods and pharmaceuticals. A consistent particle size distribution is a reason for spray drying some...

, after which it can be rehydrated. At least one brand of instant coffee is also available in concentrated liquid form.

Advantages of instant coffee include speed of preparation (instant coffee dissolves instantly in hot water), lower shipping weight and volume than beans or ground coffee (to prepare the same amount of beverage), and long shelf life
Shelf life
Shelf life is the length of time that food, drink, medicine, chemicals, and many other perishable items are given before they are considered unsuitable for sale, use, or consumption...

—though instant coffee can also spoil if not kept dry.

History

Instant coffee was invented in 1901 by Satori Kato
Satori Kato
Satori Kato was a Japanese-American chemist. Kato is best known for inventing the first soluble instant coffee and presenting the invention in 1901 at the Pan-American World Fair. American inventor George Washington created a mass-produced version of instant coffee in 1906 with Kato's work as a...

, a Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

ese scientist working in Chicago
Chicago
Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...

. Kato introduced the powdered substance in Buffalo, New York, at the Pan-American Exposition
Pan-American Exposition
The Pan-American Exposition was a World's Fair held in Buffalo, New York, United States, from May 1 through November 2, 1901. The fair occupied of land on the western edge of what is present day Delaware Park, extending from Delaware Ave. to Elmwood Ave and northward to Great Arrow...

. George Constant Louis Washington developed his own instant coffee process shortly thereafter, and first marketed it commercially (1910). The Nescafé
Nescafé
Nescafé is a brand of instant coffee made by Nestlé. It comes in the form of many different products. The name is a portmanteau of the words "Nestlé" and "café". Nestlé's flagship powdered coffee product was introduced in Switzerland on April 1, 1938 after being developed for seven or eight years...

 brand, which introduced a more advanced coffee refining process, was launched in 1938.

High-vacuum freeze-dried coffee was developed shortly after World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, as an indirect result of wartime research into other areas. The National Research Corp. was formed in Massachusetts
Massachusetts
The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...

 as a process-development company employing high-vacuum technology. It developed high-vacuum processes to produce penicillin
Penicillin
Penicillin is a group of antibiotics derived from Penicillium fungi. They include penicillin G, procaine penicillin, benzathine penicillin, and penicillin V....

, blood plasma
Blood plasma
Blood plasma is the straw-colored liquid component of blood in which the blood cells in whole blood are normally suspended. It makes up about 55% of the total blood volume. It is the intravascular fluid part of extracellular fluid...

 and streptomycin
Streptomycin
Streptomycin is an antibiotic drug, the first of a class of drugs called aminoglycosides to be discovered, and was the first antibiotic remedy for tuberculosis. It is derived from the actinobacterium Streptomyces griseus. Streptomycin is a bactericidal antibiotic. Streptomycin cannot be given...

 for US military use. As the war ended, NRC looked to adapt its processes for peacetime uses. It formed Florida Foods Corp. to produce concentrated orange juice
Orange juice
Orange juice is a popular beverage made from oranges. It is made by extraction from the fresh fruit, by desiccation and subsequent reconstitution of dried juice, or by concentration of the juice and the subsequent addition of water to the concentrate...

 powder, and originally sold its product to the United States Army
United States Army
The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...

. That company later changed its name to Minute Maid
Minute Maid
Minute Maid is a product line of beverages, usually associated with lemonade or orange juice, but now extends to soft drinks of many kinds, including Hi-C...

.

Use

Instant coffee is available in powder or granulated form contained in glass jars, sachets or tins. The user controls the strength of the resulting product, by adding more or less powder to the water, ranging from thin "coffee water" to very strong and almost syrupy coffee.

Instant coffee is also convenient for preparing iced coffee like the Greek frappé, which is popular in warmer climates and hot seasons.

In some countries such as Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

 and India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, instant coffee is commonly mixed with hot milk instead of boiling water.

Production

As with regular coffee, the green coffee bean itself is first roasted to bring out flavour and aroma. Rotating cylinders containing the green beans and hot combustion gases are used in most roasting plants. When the bean temperature reaches 165 °C the roasting begins, accompanied by a popping sound similar to that produced by popcorn. These batch cylinders take about 8–15 minutes to complete roasting with about 25-75% efficiency. Coffee roasting using a fluidized bed only takes from thirty seconds to four minutes, and it operates at lower temperatures which allows greater retention of the coffee bean aroma and flavor.

The beans are then ground finely. Grinding reduces the beans to 0.5 millimetre pieces in order to allow the coffee to be put in solution with water for the drying stage. Sets of scored rollers designed to crush rather than cut the bean are used.

Once roasted and ground, the coffee is dissolved in water. This stage is called extraction. Water is added in 5-10 percolation columns at temperatures of 155 to 180 °C; this concentrates the coffee solution to about 15-30% coffee by mass. This may be further concentrated before the drying process begins by either vacuum evaporation
Vacuum evaporation
Vacuum evaporation is the process of causing the pressure in a liquid-filled container to be reduced below the vapor pressure of the liquid, causing the liquid to evaporate at a lower temperature than normal...

 or freeze concentration.

Freeze drying

The basic principle of freeze drying
Freeze drying
Freeze-drying is a dehydration process typically used to preserve a perishable material or make the material more convenient for transport...

 is the removal of water by sublimation.

Since the mass production of instant coffee began in post-WWII America, freeze-drying has grown in popularity to become a common method. Although it is sometimes more expensive, it generally results in a higher-quality product.
  1. Agglomerated wet coffee granules are rapidly frozen (slow freezing leads to large ice crystals and a porous product and can also affect the colour of the coffee granules).
  2. Frozen coffee is placed in the drying chamber, often on metal trays.
  3. A vacuum is created within the chamber. The strength of the vacuum is critical in the speed of the drying and therefore the quality of the product. Care must be taken to produce a vacuum of suitable strength.
  4. The drying chamber is warmed, most commonly by radiation
    Thermal radiation
    Thermal radiation is electromagnetic radiation generated by the thermal motion of charged particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation....

     but conduction
    Heat conduction
    In heat transfer, conduction is a mode of transfer of energy within and between bodies of matter, due to a temperature gradient. Conduction means collisional and diffusive transfer of kinetic energy of particles of ponderable matter . Conduction takes place in all forms of ponderable matter, viz....

     is used in some plants and convection
    Convection
    Convection is the movement of molecules within fluids and rheids. It cannot take place in solids, since neither bulk current flows nor significant diffusion can take place in solids....

     has been proposed in some small pilot plants. A possible problem with convection is uneven drying rates within the chamber, which would give an inferior product.
  5. Condensation - the previously frozen water in the coffee granules expands to ten times its previous volume. The removal of this water vapor from the chamber is vitally important, making the condenser the most critical and expensive component in a freeze-drying plant.
  6. The freeze-dried granules are removed from the chamber and packaged.

Spray drying

Spray drying
Spray drying
Spray drying is a method of producing a dry powder from a liquid or slurry by rapidly drying with a hot gas. This is the preferred method of drying of many thermally-sensitive materials such as foods and pharmaceuticals. A consistent particle size distribution is a reason for spray drying some...

 is preferred to freeze drying in some cases because of its economy, short drying time, usefulness when dealing with such a heat-sensitive product, and the fine, rounded particles it produces.

Spray drying produces spherical particles about 300 micrometre (0.0118110236220472 in) size with a density of 0.22 g/cm³ (ref 2). To achieve this, nozzle atomization is used. Various ways of nozzle atomization can be used each having its own advantages and disadvantages. High speed rotating wheels operating at speeds of about 20,000 rpm are able to process up to 60,000 pounds (27 tonnes) of solution per hour (ref 3). The use of spray wheels requires that the drying towers have a wide radius to avoid the atomized droplets collecting onto the drying chamber walls.
  • Completed in 5–30 seconds (dependent on factors such as heat, size of particle, and diameter of chamber).
  • Moisture content change: IN = 75-85% OUT = 3-3.5%
  • Air temperature: IN = 270 °C OUT = 110 °C


One drawback with spray drying is that the particles it produces are too fine to be used effectively by the consumer; they must first be either steam-fused in towers similar to spray dryers or by belt agglomeration to produce particles of suitable size.

Decaffeination

In commercial processes the decaffeination of instant coffee almost always happens before the critical roasting process which will determine the coffee's flavour and aroma processes.

Composition

The caffeine content of instant coffee is generally less than that of brewed coffee. One study comparing various home-prepared samples came to the result that regular instant coffee (not decaffeinated) has a median caffeine content of 66 mg per cup (range 30–120 mg per cup), with a median cup size of 225 ml (range 170-290 ml) and a caffeine concentration of 328 µl/ml (range 100-560 µl/ml). In comparison, drip or filter coffee was estimated to have a median caffeine content of 110 mg, with a median concentration of 620 µl/ml for the same cup size.

Regarding antioxidants, the polyphenol content of a 180 ml cup of instant coffee has been estimated to be approximately 320 mg, compared to approximately 400 mg in a cup of brewed coffee of the same size.

Health effects

Compared to overall health effects of coffee, instant coffee appears to be as efficient as filtered coffee in decreasing the risk of diabetes type 2. On the other hand, it has been associated with an increased risk of bladder cancer
Bladder cancer
Bladder cancer is any of several types of malignant growths of the urinary bladder. It is a disease in which abnormal cells multiply without control in the bladder. The bladder is a hollow, muscular organ that stores urine; it is located in the pelvis...

 in women when compared to regular coffee, whereas for men both instant and regular coffee has been associated with an increased bladder cancer risk. However, current review research suggests that there is no dose-response relationship between coffee drinking and bladder cancer, and that previous studies may have been confounded by unidentified risks of bladder cancer.

Instant coffee decreases intestinal iron absorption more than drip coffee. One study estimated that, when a cup of instant coffee was ingested with a meal composed of semipurified ingredients, intestinal absorption was reduced from 5.88% to 0.97%, compared to an absorption of 1.64% with drip coffee. It was also estimated that, when the strength of the instant coffee was doubled, intestinal iron absorption fell to 0.53%. Apparently, however, there is no decrease in iron absorption when instant coffee is consumed 1 hour before a meal, but the same degree of inhibition as with simultaneous ingestion occurs when instant coffee is taken 1 hour after a meal.

Animal experiments have indicated that instant coffee confers no risk related to reproduction, lactation, embryotoxicity or teratogenicity, but possibly a risk of a delay in bone calcification in high doses.

Regulatory context

In the EU, regulations include the following details:
  • Species of coffee bean
  • Geographical origin
  • Processing detail
  • Year of crop
  • Solvents used in decaffeination
  • Caffeine level


Various institutions govern the coffee industry and help to achieve standardisation and also release information to the public.
  • International Coffee Organisation (London)
  • Codex Alimentarius Commission of the UN (Rome)
  • National Coffee Association
    National Coffee Association
    The National Coffee Association or , is the main market research, consumer information, and lobbying association for the coffee industry in the United States....

     (New York)

Non-food use

Instant coffee is one of the ingredients in "Caffenol-C", a home-made, non-toxic black-and-white
Black-and-white
Black-and-white, often abbreviated B/W or B&W, is a term referring to a number of monochrome forms in visual arts.Black-and-white as a description is also something of a misnomer, for in addition to black and white, most of these media included varying shades of gray...

 photographic developer
Photographic developer
In the processing of photographic films, plates or papers, the photographic developer is a chemical that makes the latent image on the film or print visible. It does this by reducing the silver halides that have been exposed to light to elemental silver in the gelatine matrix...

. The other ingredients in the basic formula are ascorbic acid
Ascorbic acid
Ascorbic acid is a naturally occurring organic compound with antioxidant properties. It is a white solid, but impure samples can appear yellowish. It dissolves well in water to give mildly acidic solutions. Ascorbic acid is one form of vitamin C. The name is derived from a- and scorbutus , the...

 and anhydrous
Anhydrous
As a general term, a substance is said to be anhydrous if it contains no water. The way of achieving the anhydrous form differs from one substance to another...

 sodium carbonate
Sodium carbonate
Sodium carbonate , Na2CO3 is a sodium salt of carbonic acid. It most commonly occurs as a crystalline heptahydrate, which readily effloresces to form a white powder, the monohydrate. Sodium carbonate is domestically well-known for its everyday use as a water softener. It can be extracted from the...

; some recipes also include potassium bromide
Potassium bromide
Potassium bromide is a salt, widely used as an anticonvulsant and a sedative in the late 19th and early 20th centuries, with over-the-counter use extending to 1975 in the United States. Its action is due to the bromide ion...

 as a fog-reducing agent. The active ingredient appears to be caffeic acid
Caffeic acid
Caffeic acid is a hydroxycinnamic acid, a naturally occurring organic compound. This yellow solid consists of both phenolic and acrylic functional groups...

. Initial experiments on Caffenol were performed in 1995 at the Rochester Institute of Technology
Rochester Institute of Technology
The Rochester Institute of Technology is a private university, located within the town of Henrietta in metropolitan Rochester, New York, United States...

; addition of ascorbic acid began around 2000, yielding the improved Caffenol-C, which is less likely to stain negatives than the original formulation. Experiments have shown that cheaper, less desirable brands of coffee work better for this application than more expensive brands.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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