Margaret Torbett, age 12, of Winston Salem, North Carolina, for her question:
How is sugar extracted from sugar beets?
Sugar, as we know, tends to dissolve in water. This is the basic trick used to extract the sweet stuff from the sugar beet. However, naturally, the process involves steps to handle the bulky beets and other steps to purify and refine its secret sugar supply. An average, healthy beet is expected to yield about 14 teaspoonfuls of sugar crystals and North America produces about twenty millions tons of sugar beet sugar during an average year.
The pasty colored sugar beet looks somewhat like an extra wide, extra long turnip. Its bulky top is four to six inches wide and its tapering tip is between one and two feet long. This underground storage root is topped with a crown of large oval leaves. They may be cooked as green vegetables, eaten in raw salads or fed to cattle. The sweet sugary stuff is stored in the root and most of it is concentrated in the tapering tip.
The crop is harvested after a long, rather moist summer season. Farm machines are driven up and down the rows, pulling up the roots and slicing off their green tops. The beets are sent to a sugar processing factory, where the first operation is a thorough scrubbing to remove the clinging crumbs of dirt.
The spanking clean beets are chopped into thin slices called "cossettes." A slicing machine does this job very fast. Then the cossettes ate dunked in very hot water and left to soak and soak. Naturally the sugar content dissolves and seeps out into the water. The result is a mixture of beet pulp and a thin sugary liquid. The dark liquid contains from 10 per cent to 15 per cent sucrose type sugar, plus some nitrogen compounds and traces of various mineral salts.
The next step is to clear the dark juice of impurities and some of its unwanted, nonsugary ingredients. This is done by a carbonating process. Lime is added to the juice and carbon dioxide gas is bubbled through the liquids. These two additives react with each other and form granules of solid calcium carbonate. This chemical latches onto most of the impurities and deposits itself on the bottom.
The mixture is filtered to remove the calcium carbonate, along with its load of impurities. The sugary juice is now much paler. As a rule, its remaining color is removed by a process using vegetable carbon. The water is evaporated from the colorless, purified juice and its sugar crystals stay behind to be packaged and sent to market.
At one stage, a rather elaborate process may be used to extract rich syrupy molasses from the sugar beet juice. Some of the beet molasses is fed to cattle and some is sold to yeast manufacturers. Betaine may be extracted from sugar beet wastes and also a flavor enhancer known as MSG, alias monosodium glutamate.