Sugar & Molasses
Sugar (sucrose) is a natural carbohydrate found in all fruits and vegetables. All green plants manufacture sugar in various forms, including sucrose and glucose, through photosynthesis. Sugar cane and sugar beet plants contain the most accessible stores of sucrose, the sugar we ferment to make alcohol. Alcohol made from sugar cane is called rum. Alcohol can also be made from less accessible sources of sucrose, such as grapes or grains.
Almost every rum distiller will tell you about the quality of the sugar cane used to make their rum. In reality, most rum is made from imported molasses, the byproduct of the sugar-making process. In order to appreciate the differences in rum, it's helpful to understand how sugar and molasses are made.
After growing nine to twelve months in the tropical regions of the world and reaching a height of 10 to 12 feet, the mature, hard, sweet sugar cane stalks contain 12-14% sucrose. They are harvested by machine or hand, depending on the terrain and the cost of labor.
Next, the sugar cane stalks are washed and chopped into shreds by a series of rotating knives. Huge rollers press the juice out of the shredded pulp. In the production of rhum agricole, it is this freshly-squeezed sugar cane juice that is fermented and then distilled.
At distilleries that make rum from molasses, the molasses is purchased from either a local sugar mill or from a foreign supplier. In order to make sugar and molasses, the cane is harvested and crushed in the same manner as above, though on a larger scale. Lime is added to the fresh juice and carbon dioxide is bubbled through the mixture to form calcium carbonate, which is precipitated and then removed.
The clarified juice is concentrated by removing the water in vacuum pans which boil the juice at lower temperatures and protect the sugar from carmelization as the juice becomes a rich brown syrup.
As the last portion of water is removed under a carefully controlled vacuum, seed grain (pulverized sugar) is fed into the vacuum pan and thick dark crystals grow. These crystals are then separated in centrifuges, large perforated baskets that yield golden raw sugar.
Raw sugar - approximately 96-98% sucrose - is covered by a thin film of molasses, a dark thick syrup containing sugar, water, plant material, minerals, and other non-sugars. The composition of this molasses is dependent on the efficiency of the sugar manufacturing equipment and the source of the fresh sugar cane.
To remove the molasses layer on raw sugar, the sugar is dissolved and then separation is accomplished in centrifuges and carbon filters to yield a water-white sugar syrup and thick dark molasses. From the water-white sugar syrup sugar crystals are formed in vacuum pans, centrifuged and dried before being separated according to size. Since the pure sugar crystals are naturally colorless, no bleaching or whitening is necessary.
Turbinado sugar is sugar that has been refined to a light tan color by washing it in a centrifuge under sanitary conditions to remove the surface molasses. The carbon filtering step, above, is skipped.
Confectioners (powdered) sugar is made up of much finer particles than granulated sugar and contains about 3% corn starch (to prevent caking).
Brown sugar consists of sugar crystals in a specially prepared molasses syrup with controlled natural flavor and color components.