Sucrose, the most popular sweet food and food sweetener
2000
Su, J.C.
Sugar cane and sugar beet are the two major sources of sucrose manufactured as the food. The manufacturing process takes advantage of the non-reducing property of sucrose. It starts from the juice extraction by milling of cane stalk or diffusion from beet slices. The juice is clarified by liming and carbonatation or sulphitation. Sugar crystals are isolated through vacuum evaporation and removal of molasses. Molasses is used mostly as the sugar source in fermentation industries. Being the primary neutral product of photosynthesis and the major form of carbon transport sucrose is found ubiquitously in green plants. Its in vitro synthesis was first achieved by using a reaction catalyzed by the sucrose phosphorylase from Pseudomonas saccharophila. The synthesis in plants is an irreversible process catalyzed by sucrose phosphate synthase and sucrose phosphate phosphatase from uridine diphosphate D-glucose (UDPG) and D-fructose 6-phosphate. Sucrose synthase catalyzes a freely reversible reaction using UDPG and D-fructose and is considered as an agent to synthesize sugar nucleotide from sucrose in vivo. A futile cycling of sucrose synthesis and degradation in plants may be a mechanism of regulating cellular level of sucrose which exerts an important metabolic regulatory function at the levels of from gene expression to enzyme catalysis. Besides being a major source of carbon for sustaining plant life, sucrose also serves as the glycosyl donor in synthesizing oligo- to polysaccharides, especially of fructans including inulin and phlein in plants and levan in bacteria. In the industry, sucrose is used as a polyhydric compound in the preparation of various forms of esters. Those having many hydrophilic hydroxyl groups free is used as a biodegradable detergent, and that wholly, or nearly wholly esterified with fatty acids are resistant to hydrolysis by lipases, and used as a fat substitute in treating obesity and hypercholestrolmia.
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