CARBOHYDRATES 



43 



very high, running to over 100 lbs. in most years. The desirabiUty of 

 such a Large consumption of sugar is doubtfuL Sugar suppUes about one- 

 sixtli of the cahiric intake and hence displaces the consumption of less- 

 refined foods that would carry minerals and vitamins as well as energy, 

 Sherman, who has given much thought to this matter, suggests that, 

 instead of devoting so much land, labor, and money to the production 

 of sugar, it would be a wiser policy to increase the production and con- 

 sumption of foods which furnish needed nutrients as well as calories. 

 However, it should be pointed out that sucrose is one of the very cheapest 

 sources of food energy. A comparison of various low-cost foods from 

 this standpoint is given in Table 3-4. 



— The manufacture of sucrose is an excellent example of a chemically 

 controlled industry. From the determination of the sugar content of 

 the raw beet to the analysis of the finished product, it is an application 

 of the principles involved in the preparation of any pure chemical. Ex- 

 traction, clarification, evaporation, and crystallization are the important 

 steps involved. Because of the ease w'ith which sucrose crystallizes, it 

 lends itself readily to this method of purification. 



Sucrose is sweeter than glucose but not so sweet as fructose. It is 

 claimed by the majority of investigators that invert sugar, which is formed 

 when sucrose is hydrolyzed, is sw-eeter than sucrose, but there is consider- 

 able difference of opinion on this point. It is difficult to determine the 

 comparative sw^eetening power of sugars owing to the fact that small 

 differences in concentration cannot be detected by the sense of taste. 

 For example, sucrose solutions differing by less than 1.5 per cent cannot 

 be readily distinguished. Some of the sugars have other tastes tlian 

 that of sweetness, which complicates the comparison. The compara- 

 tive sweetness of sugars, giving sucrose a value of 100, has been rated 

 as follows: lactose 16, raffinose 23, galactose 32, rhamnose 33, mal- 

 tose 33, xylose 40, glucose 74, sucrose 100, invert sugar 130, fructose 



173. 



In cooking operations, such as the making of jelly where sucrose is 

 hydrolyzed, it would seem that the proper time to add the sucrose is 

 at the beginning of the cooking. This insures the maximum hydrolysis 

 of sucrose, and consequent maximum sweetening power. Moreover, the 

 hydrolysis products, glucose and fructose, prevent crystallization (grain- 

 ing) of unhydrolyzed sucrose and give the best conditions for producing 

 a jelly of smooth texture. Approximately 50 per cent of the added 

 sucrose is converted into invert sugar by the usual methods of jelly 

 making. Any cooking operation that involves the use of sucrose and 

 acid, such as the canning of fruit and making of jams and of many 

 kinds of pie, will bring about a considerable hydrolysis of sucrose. It 

 is probable that in many other cooking operations sucrose undergoes 

 slight hydrolysis as a result of the effect of salts and other food con- 

 stituents. 



