FoodNet

Experimental cookery

1932

Page 37

Presented as published in 1932. Historical recipes may not meet modern food-safety standards. Cook from the modern interpretation, not the original instructions.
Addition of other substances. Two forms of the same compound may give different solubilities. Thus anhydrous lactose (without water of crystallization) has one solubility and the hydrated form has another. Some- times the addition of another substance, organic or inorganic, to the solu- tion will increase or decrease the solubility of the solute. If, after all the sucrose possible is dissolved, some potassium acetate, sodium chloride, or SUCROSE 41 many other salts, is added to the solution, more sucrose can be dissolved. This may a£Fect the solubility of sugar in candy making, for it is known that different waters, with different proportions and kinds of minerals, do not always give identical results, with the same sugar, for the same kind of candy. Saturated solutions. Once all the solute is dissolved that can possi- bly be held by a definite amount of solvent at a constant temperature, any excess of the solute remains unchanged. The saturated solution is one that contains all the dissolved solute that it can take up when in contact with undissolved solute. In other words, it is a solution which when placed with excess of the solute at a definite temperature is in equilibrium, i.e., there is neither increase nor decrease in concentration of the solute. Supersaturated solutions. One should not define a saturated solution as one containing all the solute it can hold, for a supersaturated solution holds more than a saturated one. If water is heated to 70°C. and all the sucrose added that can be dissolved by the water at this temperature, one has a saturated solution. There should be no excess of the solid left with the liquid. If this solution is carefully cooled to 40°C. without stirring more sucrose will .be in solution than could have been if the water had not been heated above 40°. The cooling of a saturated solution leads to the formation of crystals, and any excess beyond saturation is gradually pre- cipitated as the temperature drops, though crystallization may not begin immediately. But some substances, like the sugars, require longer than others for crystallization to commence, unless the solution is stirred or agitated. The Solubility of the Sugars The solubility of the sugars determines their use to a certain extent. It is obvious to one who does a great deal of cooking that a sugar that requires 6 pounds of water to dissolve 1 pound of sugar, could not be used for con- centrated sugar products like jellies, jams, frostings, or even cakes. Sucrose. Sucrose has the greatest solubility of the disaccharid sugars. Browne in his "Handbook of Sugar Analysis" states that, at 20°C., 204 grams are soluble in 100 cc. of water. Thus at room temperature about 2 grams of sucrose are soluble in 1 cc. of water. At 100°C. 487 grams of sucrose are soluble in 100 cc. of water. For solubilities at other tempera- tures see Table 5. In Table 5 the solubility of sucrose is expressed in two ways. In column 2 is given the amount of sucrose dissolved in water to make 100 grams of solution. Thus at 0°C., 64.18 grams of sucrose are dissolved in 35.82 grams of water to give a total of 100 grams of solution. The third column states the number of grams of sucrose dissolved in 100 grams of water at a definite temperature. 42 SUGAR COOKERY TABLE 5 Solubility of Sucrose in Water at Different Temperatures {From Browne's '^Handbook of Sugar Analysis^') Temperature,