In purchasing the raw beans, one should also though bear in mind that : (1) If all of one variety (i. e., before blending), they should be fairly uniform in size, appearance and color.
(2) They should be free from stems, stones, dirt and all such foreign matter.
(3) When cut, they should be the same general color all the way through. If the inside is considerably lighter than the outside, it will usually be found that the beans have been artificially colored.
Simple tests for ground coffee are: (1) Press a little of the dry coffee between the fingers—if it cakes, it is adul terated, probably with chicory.
(2) Place a little of the dry coffee in a glass of water. If nearly all floats and the water does not color—or only a very little—the coffee is probably pure. If part of the coffee floats and part sinks, it is adulterated—probably with cereals, chicory or similar substances. If the water turns a deep reddish tint, chicory has been added to it.
(3) Spread a little dry coffee on a piece of glass or something similar and moisten with at few drops of water. Then pick out some of the smallest pieces with a needle—if they are soft, the coffee is certainly adulterated, as real coffee bean particles stay hard even after long immersion in water.
It must be remembered that the above tests apply only to the purity of the bean —they tell nothing of the flavor or aroma, which are determining points of value. A coffee may be perfectly pure, yet be harsh, musty, hidey or in many other ways undesirable—hence the necessity of testing flavor and aroma by making an infusion.
Coffee Roasting.
The proper roasting of coffee alters its appearance and flavor by bringing about important changes in the component parts of the bean. It develops the "caffeine" (the active principle of coffee, corresponding to the theine in tea), by separating it from the tannic acid, frees the highly aromatic coffee-oil (the amount and quality of which largely determine the value of the roasted product), renders the fat more easily soluble by releasing it from the fat cells, and reduces the natural sugar while convert ing the saccharine matter into caramel. The result is that after roasting the bean
readily releases the flavor and aroma for which it is famous and will, by thorough infusion in boiling water, yield a total of more than 40% of soluble matter—though in ordinary coffee making only from 10% to 15% is actually extracted.
The roasting in the average modern United States plant is preceded by passing the beans through a cleaning and milling machine which removes all foreign matter and gives a smooth finish. From this they go into large revolving perforated steel or iron cylinders, encased in t; ick and revolving over brisk fires. The cylinders are fitted with interior lateral rid f..es which keep the beans constantly moving in order that they may not become "tipped" or scorched. The time of roasting varies, but generally takes thirty minutes for a "light," and from thirty-five to forty-five minutes for a "high" or "dark" roast.
From the roaster, the beans pass to I he "coolers," fitted with powerful exhaust fans which draw cold air through them to stop the roasting process, and then to the "stoner," which is an air-suction pipe generally about twelve inches in diameter and ten feet in height, the coffee being drawn up this pipe into a hopper, leaving the stones at the bottom to be discharged automatically. Finally comes the filling, by machinery, into bags, cans, etc.
The operation of roasting is easy to describe, but it requires much experience and good judgment to bring out the full strength, character and aroma.
A "light" roast should be of a cinnamon-brown color, uniform in appearance and free from specks. A "medium" roast should be deep chestnut. A "high" or "dark" roast should be of a chocolate-brown color and oily in appearance but free from burnt or scorched beans—which will spoil the flavor of any coffee, no matter how high grade. The "medium" roast is the most desirable for general retail cus tom.
So important is this process that a well roasted minor grade will yield a better liquor than the finest coffee a little under or over roasted.