FoodNet

Experimental cookery

1932

Page 35

Presented as published in 1932. Historical recipes may not meet modern food-safety standards. Cook from the modern interpretation, not the original instructions.
All sugars should be stored in a dry place for they deteriorate if stored where it is damp. This power of absorbing moisture can be made use of to improve some foods, but it is a detriment in others. Browne reports that the sugars having the highest absorptive power from a saturated atmosphere are the levulose-containing substances : invert sugar, honey, levulose, and molasses. He finds that the percentage of water ab- sorbed has no relation to the percentage of levulose present. This would suggest that cakes made with levulose-containing products would not dry out so rapidly as cakes made with sucrose. In practise, this is found to be true. Cakes made with part levulose or levulose-containing substances do not dry out so rapidly as those made with sucrose. Honey and molasses are used in many family recipes for cookies, par- ticularly the kinds made for holidays, for they can be made a long time in advance of their intended use and they remain moist with storage — in many instances the moisture content seems to increase during storage. Invert sugar either added to food or formed by inversion during cooking is found in many food products. In the bakery trade it is used to prevent SOLUTIONS 39 drying and checking. The acid in fruits inverts sucrose. The amount of total sugar that can be held in solution in a given quantity of liquid is greater if it contains a mixture of sucrose, levulose, and dextrose. Rich preserves made of fruit containing little acid do not crystallize so readily during storage if lemon juice is added when they are being made. The lemon juice brings about more inversion than the less acid fruit juice. The invert sugar does not crystallize so readily as the sucrose, the total quantity of sugar held in solution is greater, and there is less evaporation. The levulose-containing substances should be avoided for hard candies. Duryea states that maltose is better to use in hard candies than dextrose, because the candies remain drier. He also adds that another advantage of using maltose in hard candy is that maltose is not so readily affected by alkali. The decomposition caused by use of dextrose and alkaline w^ater is avoided. The Melting Point of the Sugars and the Effect of Heat When sugars are heated without the addition of water a point is reached at which they change from a crystalline to a liquid state. This is called the melting point. Mackenzie states that the melting point of sucrose is 160° to 161 °C. Impure solutions of sucrose will give variable melting points. After sugar is melted and cooled slowly it forms the hard amorphous sugar sometime? called ''barley sugar." The amorphous form of sugar like the amorphous sulfur slowly reverts to the crystalline form. If sucrose is heated above the melting point brownish-colored substances called caramel are formed. In the presence of moisture, caramelization may begin at temperatures below 100°C. Caramel is composed of a number of substances, decomposition products of sucrose with loss of water. Maltose melts at about 100°C. Having a lower melting point than sucrose it decomposes more easily by heat.