The Hygroscopic Nature of Sugar

All sugars are hygroscopic, at least to some degree, meaning that they attract and bond to water. Because sugars are strongly attracted to water, they can pull water away from other molecules including proteins, starches, and gums. When this occurs in batters and doughs, the batters and doughs soften and thin out as sugar is added. The proteins, starches, and gums become less hydrated, so they trap less water. The water is released to sugar, forming a thin syrup as part of the batter or dough. Figure 8.5 shows this, where a seemingly dry powder made from starch and water is liquefied by the addition of dry sugar.