Unsulphured molasses is the finest quality. It is made from the juice of sun-ripened cane and the juice is clarified and concentrated. Sulphured molasses is made from green (unripe) sugar cane and is treated with sulphur fumes during the sugar extraction process.
Each season, the sugar cane plant is harvested, and stripped of its leaves. Its juice is then extracted from the canes (usually by crushing or mashing), boiled until it has reached the appropriate consistency, and processesed to extract the sugar. The results of this first boiling and processing is first molasses, which has the highest sugar content because comparatively little sugar has been extracted from the juice. Second molasses is created from a second boiling and sugar extraction, and has a slight bitter tinge to its taste. Further rounds of processing and boiling yield blackstrap molasses, used in the manufacture of cattle feed, as well as having other industrial uses.
Interestingly, molasses is also an excellent chelating agent. An object coated with iron rust placed for two weeks in a mixture of one part molasses to nine parts water will lose its rust due to the chelating action of the molasses.
A famous incident involving molasses was the Boston Molasses Disaster on January 15 1919, in which a large molasses storage tank burst and flooded a neighborhood of Boston, killing 21 and injuring 150.