FND 300 Chapter Notes - Chapter 2: Ice Crystals, Histidine, Freeze-Drying
3 Nov 2017
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Document Summary
Of the eight d-aldohexoses only d-glucose has a possible conformation in which all of its hydroxyl groups and the hydroxymethyl group are equatorial. This is the explanation for the dominant role of glucose in living systems both as a metabolic intermediate and as a structural element. There is 37% of the a-anomer of d-glucose at 25 degrees in aqueous solution, but 45% when the solvent is pyridine is just one indication of the existence of strong interactions between water and sugar molecules. The binding of water to sugars and polysaccharides is an important contributor to the properties of many foodstuffs. The most obvious indication of the binding of water by sugars is that concentrated solutions of sugars do (cid:374)ot o(cid:271)ey raoult"s la(cid:449) Raoult"s law: the relative lowering of the vapour pressure of the solvent is equal to the molecular fraction of the solute in solution.
