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Just what is brown sugar?

October 3, 2011

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Is brown sugar made from white sugar, or is white sugar purified brown sugar? Which is more fattening?

To understand this, it’s a good idea to start with the origins of sugar, which comes in many different forms.

Common white table sugar, called sucrose, is made of two simpler sugars, fructose and glucose, joined together. Sucrose, which is naturally white, is usually derived from sugar cane or sugar beets.

The process of extracting the sugar is the same for both: The juice is filtered to remove plant matter and boiled down. What’s left is a thick syrup from which sucrose starts to crystallize. The syrup is spun in a centrifuge to separate out the crystals, which then make up what is called raw sugar. The rest is molasses.

The separation of sugar from juice is never perfect. A first pass yields impure sucrose (natural brown sugar, or raw sugar) and molasses, which is still quite sweet and is called “first molasses.’’

Boiling molasses and crystallizing sucrose out of it again leaves “second molasses’’ and if it is done again, it is called “third molasses,’’ or “blackstrap molasses.’’

If the sugar is not refined further, it will be brown sugar; if it is refined further, the result is a pure form of sucrose, or white sugar.

Also, molasses is sometimes added to refined white sugar to make a brown sugar.

However it is made, brown sugar is essentially incompletely purified sugar colored and flavored by other plant matter, which answers the first question.

As for which is more fattening, it depends to some extent on how its calories are measured.

Brown sugar has a slightly lower calorie content by weight, with typically 373 calories in 100 grams versus 396, since it has more water, which has zero calories, and other nonsugar plant matter in it.

But there are many grades of brown sugar with differing caloric counts and since brown sugar packs more compactly than refined white sugar, it can have more calories by volume.

E-mail questions to or write to Dr. Knowledge, c/o The Boston Globe, P.O. Box 55819, Boston, MA 02205-5819.