The possibility of preparing an extract from coffee was considered as early as 1838, when the United States Congress substituted coffee for rum in the rations of soldiers and sailors.
Probably the first powdered instant coffee was invented by Sartori Kato, a Japanese chemist living in Chicago. He first sold his soluble coffee at the Pan American Exposition in Buffalo in 1901. Soluble coffee was first marketed on a broad scale in the United States by the American chemist G. Washington in 1909. However, the demand for the product remained small until World War I when the entire output of all soluble coffee in the United States was purchased by the War Department for troops in the field. During World War II the government bought almost 260 million pounds (118 million kg) of instant coffee. By 1953 one cup of coffee in 10 was instant; a more recent estimate is one cup in five.
The coffee tree is cultivated in the cooler regions of the Tropical Zone. It prefers a rich, well drained, volcanic soil and a warm humid climate. The trees can be planted directly in the soil but are usually propagated in special nurseries and then transplanted into the field. Coffee trees take about 5 years to produce their first full crop, and they continue to bear berries, or beans, for up to 30 years and produce an annual yield of about half a kilogram per tree.
Of more than 30 species only three are important: Coffea arabica, Coffea robusta and Coffea liberica.
How is it made?
While ground coffee has its mystery and romance, instant coffee is all business. The oldest method of processing is known as spray drying. It begins with a large number of bags of undistinguished bags of robusta and liberica coffee being blended and roasted very dark. No quality beans are used, as it would be too expensive, and the subtle flavor would be lost. The roast is ground and put into a building-size percolator, and brewed under very high pressures and temperatures, where the water is evaporated from the extract. This causes the cellulose in the coffee to be converted into soluble carbohydrates, creating bulk - while taking away most of the flavor.
This brew is then spread into a tall drying chamber in which hot air is circulated. When the coffee reaches the bottom of the chamber, all the water has evaporated, and the grains of powder are left. This is "instant" coffee.
Decaffeinated coffee is made by several methods; each treats the green coffee to remove the caffeine. The decaffeinization processes creates a refined caffeine byproduct which provides a major source of caffeine for the chemical and drug industries.
Later the process of "freeze-drying" was developed, and the result was the coffee looked and tasted better. Instead of subjecting the coffee to steam - a steam which over-extracts the flavor - the percolated coffee is cooled to a slushy consistency, frozen solid and broken into granules. It is then placed in a vacuum chamber, where the air pressure is lowered as the temperature is raised. The water is removed by sublimation (the water is drawn off and the solid granules remain). More of the flavor is retained than in the older method, but at least 31 percent of the coffee is no more than carbohydrate bulk. The product is packed in vacuumized, sealed jars or in cans.
What about the aroma?
The coffee manufacturers try to simulate the aroma of real coffee by adding coffee oil to the finished product. This creates an aroma when the jar is first opened. But it doesn't add anything to the real flavor. And the coffee powder tens to turn rancid after the jar has been left standing.