Sulphured vs. Unsulphured — Sulphured molasses is the bi-product of sugar that has been processed with sulfur dioxide. Sulfur dioxide is most commonly used when the sugar cane is very young or green (to help ripen it), or as a means of lightening the color of molasses, and to kill off some of the naturally occurring bacteria in order to give it a longer shelf life. Sulfur is commonly used as a preservative in foods like dried fruit, to prevent oxidation. The FDA considers sulfur dioxide to be safe, though it is required that foods processed with it are labeled as such, as some people (especially those with asthma) can have an allergic reaction to it.
Unsulphured molasses is made from sugar that has not been processed with sulfur dioxide. Because it is untreated, unsulphured molasses is often considered healthier than sulphured. It also means that the sugar cane was allowed to ripen fully before harvesting, which may affect the nutritional and flavor profile of the molasses. Unsulphured molasses tends to have a less bitter taste than its sulfur treated counterpart.
Light and Dark Molasses — cane sugar goes through several phases of refining. In the first phase, the cane juice gets boiled until the sugar crystals begin to separate from the liquid, then spun through a centrifuge which separates the sugar from the molasses. This first processing is called mild, or first molasses. It is the sweetest and lightest of all the grades. The syrup then gets re-boiled and spun again to remove more of the sugar. This results in a darker syrup called second molasses. On the third boiling, many of the remaining sugars begin to caramelize, darkening the syrup even further. This final extraction of molasses is called blackstrap. This is the darkest grade available, with a somewhat bitter flavor. Blackstrap molasses is often used for its nutritional benefit, containing nearly 20% of our daily need for calcium, magnesium, potassium, and iron per tablespoon, among others (though this may vary depending on brand).
Molasses in Cooking — molasses has many uses in the culinary world, but is most often used in baking. Because molasses is naturally acidic, it can be used alongside baking soda to help baked goods rise. Molasses also contains a type of sugar called invert sugar (the result of boiling sucrose with an acid) which is particularly hygroscopic (meaning it holds onto moisture well). This can help baked goods stay soft and fresh longer. Molasses is also used in the making of many beers and liquors, and in recipes like stews, chili’s, and baked beans. Lighter, sweeter molasses can be used as syrup on pancakes, a spread for biscuits or toast, or used in other applications as a substitute for maple syrup or honey.
Molasses can also be made in the refining of beet sugar, though it is considered unpalatable for human consumption and therefore used mostly in animal feed. In some parts of the world, different types of molasses are made from carob, dates, grapes, pomegranates, or other fruits, and can go by a variety of different names.