By Harold McGee
Molasses, which is called treacle in the United Kingdom, is generally defined as the syrup left over in cane sugar processing after the readily crystallizable sucrose has been removed from the boiled juice. (There is such a thing as beet molasses, but it has a strong, unpleasant odor, and so is used to feed animals and industrial fermentation microbes.) In order to extract as much sucrose as possible from cane juices, crystallization is performed in several different steps, each of which results in a different grade of molasses. “First” molasses is the product of centrifuging off the raw sugar crystals, and still contains some sucrose. It is then mixed with some uncrystallized sugar syrup, recrystallized, and recentrifuged. The resulting “second” molasses is even more concentrated in impurities than the first. Repeating this process once more yields “third,”or final, or “blackstrap” molasses (from the Dutch stroop for “syrup”). The brown-black color of final molasses is due to the extreme caramelization of the remaining sugars and to chemical reactions induced by the high temperatures reached during the repeated boilings. These reactions, together with the high concentration of minerals, give final molasses a harsh flavor that makes it generally unfit for direct human consumption, although it’s sometimes sold blended with corn syrup. A small amount is also used in tobacco curing.