Chemical and Functional Properties of Food Saccharides

© 2004 by CRC Press LLC
cane quality, and the type of clarifier. The scum from clarifiers (precipitate) is mixed
with the final bagasse, filtered, and desweetened on a rotary vacuum filter.
Either sulfitation (addition of SO 2) of cane juice prior to the liming or liming
prior to the sulfitation is commonly used to achieve mill white sugar. Better sedimentation
of slurry is achieved when the sulfitation precedes liming. Calcium sulfite
is precipitated in the process and the clarified juice with 12−16% solids is passed
through a multiple-effect evaporator, producing a thick juice containing 60−70% of
dry substance.
Cane juice, after concentration in evaporators, is of lower purity than that of the
thick beet juice. It contains more reducing sugars (5−13%) and high-molecular
components (0.4−3%). Commercial cane sugar is crystallized in three stages. The
C massecuite is centrifuged in continuous centrifuges to yield C sugar and final
molasses. The C sugar of about 85% purity is mixed into a magma, which is used
as a seed for the A and B crystallization stages.
4.3.1 BY-PRODUCTS AND WASTE
Bagasse is the major by-product in cane sugar production. It is used, first of all, as
the source of energy available from combustion. Methane can also be produced from
bagasse. Other uses of bagasse are composting for fertilizer for cane plantation,
paper and board manufacture, and cattle fodder. Methods of utilization of molasses
and lime mud are common for both technologies of sucrose production.
4.4 PRODUCTION OF OTHER SACCHARIDES
ESSENTIAL IN FOOD TECHNOLOGY
Apart from sucrose, D-fructose, D-glucose, and lactose have found wide application
in food technology. Importance of D-fructose arises, most importantly, from its
insulin-independent metabolism, nonpromoting formation of cavities, and hygroscopicity,
the latter frequently employed to preserve moisture in foodstuffs. Its
sweetness, higher than that of sucrose (Chapter 5), is an additional advantage of that
saccharide. D-Glucose is most commonly used as the source of the “fast” energy in
the recovery stage after various medical treatments or strenuous activity. Lactose is
frequently used as a carrier of other sweeteners and as an additive to improve the
taste of dairy products and the appearance of microwave-heated foodstuffs.
D-Fructose and D-glucose are currently produced in biotechnological processes,
preferably from enzymatically saccharified starch (Chapter 10). In the first part of
the last century, considerable attention was paid to saccharification of wood in the
acid-catalyzed processes as the source of D-glucose.
Lactose is moderately soluble in water (ca. 20 wt% at 20°C). It is most readily
available from whey (almost the 5% content) by careful evaporation in order to
achieve crystals in the preferred β form. Fast evaporation results in the crystalline
α form of lactose which, when present in food, produces sandiness.