Union soldiers in the American Civil War were issued Essence of Coffee, a gritty paste they compared to axle grease. This episode follows how that sludge became a $34 billion industry. David Strang of New Zealand patented a dry hot air process, Satoru Kato showed a powdered coffee at the 1901 Pan American Exposition, and George Constant Lewis Washington put a product on shelves in 1910, but his powder was so hygroscopic it clumped back into paste. In 1938 Nestlé chemist Max Morgenthaler solved it by making the original Nescafé half coffee solids and half maltodextrins, and in the 1950s General Foods reached 100% coffee by extracting the bean’s own polysaccharides at up to 175 degrees Celsius under pressure.

Inside the plants, spray drying towers fling extract off titanium wheels spinning around 20,000 RPM, drying droplets in 5 to 30 seconds, while freeze drying, launched by Maxwell House in 1963, uses vacuum sublimation that puffs granules to ten times their volume. Captured roasting gases are sprayed back on as aroma, and spent grounds are burned as plant fuel. A cup carries about 66 mg of caffeine against 112 mg for drip, and it cuts iron absorption sharply when drunk with a meal. The UK took to it through GI rations in World War II, and a 1995 Rochester Institute of Technology class turned it into a film developer called Caffeinol.

• Roughly half of the world’s green coffee goes into instant coffee production.
• Steam agglomeration, used since about 1968, clumps fine spray dried dust into familiar granules.
• Iron absorption fell from 5.80% with water to 0.97% with instant coffee, and to 0.53% at double strength; drinking it an hour before the meal removed the effect.
• Instant coffee is 77% of UK coffee sales, compared with 1% in Italy and 7% in the United States.
• Life cycle studies find a lower footprint per cup than drip or pod coffee, thanks to light shipping and no wet grounds at home.