144 Principles of Food Science each hydroxyl group. These groups are then attracted to the polar water molecules, and hydrogen bonds are formed. These hydrogen bonds cause water molecules to surround the sugar molecules, suspending the sugar in a water solution. See 8-10. Sugar’s ability to dissolve in water increases as the temperature of the solution increases. The temperature of sugar solutions will steadily climb as heat is added. As the solution heats, water evaporates. This changes the solute-to-solvent ratio, increasing the sugar concentration. If a sugar solution has been heated to concentrate it and is then cooled, a supersaturated solution is created. Any solution that has been heated to dissolve more solute than the water would normally hold is called supersaturated. to the sugar content in the dough. You can observe the same characteristic by comparing a bread-type muffin and a basic white or yellow cake. See 8-9. The tenderizing effect of sugar also changes the viscosity or pourability of a batter. Sugar interferes with the flour’s ability to form an elastic structure, which allows the batter to flow or pour more easily than the same mixture without sugar. Crystallizing Agents In candies, sugars function as crystallizing agents. This function is linked to the solubility of sugars in water. Solubility is the ability of a solute to dissolve in a solvent. Sugar will dissolve in water because of its large number of hydroxyl groups. The position of the -OH causes the sugar molecule to have a polar nature near • Fine grinding and screening remove fiber. • The enzyme α-amylase is added to convert starch to oligosaccharides. • The enzyme glucoamylase breaks the molecules down into glucose molecules. • A third enzyme, D-xylose isomerase, transforms the glucose into fructose. • Varying levels of dextrose and fructose are determined by processing time and number of enzymes used. • Corn syrup and high-fructose corn syrup are mixed to get desired fructose level. STEM Matters Manufactured or Natural? Sugar from sugar beets and sugarcane: • The beet or cane is ground to extract juice. • The juice is boiled until syrup thickens and crystallizes. • The crystals are spun in a centrifuge to produce raw sugar (turbinado sugar). • The raw sugar is shipped to a refinery. • The raw sugar is washed and filtered to remove remaining nonsugar ingredients and color. • The sugar is crystallized, dried, and packaged. Corn syrup from corn: • Corn kernels are wet milled. • The germ is removed and made into corn oil and animal feed. wavebreakmedia/Shutterstock.com Alessio Orru/Shutterstock.com 8-9 Sugar helps tenderize cakes, pastries, and doughnuts. The Italian bread on the right has a paler color and chewier texture because it does not contain any sugar. Copyright Goodheart-Willcox Co., Inc.