We who write espresso machine reviews were curious about how instant coffee is manufactured. So we did some quick research on the topic and here is what we found.
Along with tea, coffee has become one of the world's most popular drinks. While most coffee consumed is fresh brewed, a small fraction is made from instant coffee granules, which allows people to make coffee quickly, easily, and without any complicated brewing equipment.
Instant coffee starts as berries from the coffee plant, a tall evergreen shrub growing primarily in tropical regions. The mature fruit, which resembles a cherry, usually contains two seeds or beans surrounded by sweet pulp. This sweet pulp is removed, and the beans are dried and roasted to remove the moisture, bringing out the distinctive rich, bitter flavor of the coffee.
In manufacturing instant coffee, the roasted beans are first coarsely ground to enable water to percolate freely through the coffee grounds. The water passes through the grounds in several "hot" cells (140-180°C) and then passes through two or more "cold" cells (100°C). This temperature variation allows the different flavors in the coffee to be extracted efficiently. The liquid extract is then cooled to about 5°C. At the end of this cycle, the coffee extract contains 20-30% solids.
After filtering, additional water is removed to increase the concentration of solids in the liquid to 40%. This is accomplished by either evaporation or by freezing and mechanically separating the ice crystals from the solids. This step aids in the subsequent drying process. Oxygen is then removed from the liquid by bubbling carbon dioxide or nitrogen through it. This step helps in preserving the aroma of the final product.
The next step is to remove the bulk of the remaining water to yield the solids forming the instant coffee particles. There are two methods for this. The first is to spray the liquid in a large chamber while flowing heated air to remove the water from the droplets, leaving behind only the coffee solids. This is the cheaper and quicker method, although the heat compromises some of the flavor of the instant coffee. The second method is freeze-drying, which freezes the concentrated liquid, then breaks it up into small pieces. The water is then removed from the ice mixture by sublimation under vacuum with the application of a modest amount of heat.
The entire process results in a loss of aroma in the coffee, and the aromatic elements of coffee are added back prior to packaging. These aromas are recovered from gases collected from coffee roasting or by using steam to capture aromas from coffee grounds. Additionally, oils from coffee grounds can be extracted using high pressures. The captured aromatic compounds are sprayed onto the instant coffee particles immediately before packaging.
The final stage is packaging, which occurs in a dry, oxygen-free environment to preserve both the flavor and the aroma of the final product.
Instant coffee goes through a remarkable, well-engineered process to go from the coffee fruit to the final dry granules. Advances over the years have improved both the taste and fragrance of the instant coffee that reaches the tables of consumers everywhere.
