148 DAIRY TECHNOLOGY 



ing about a dollar, will produce the same results as will six 

 to eight pounds of a cheaper grade costing 50 per cent more. 



At the present time gelatin is being replaced to some 

 extent by gum tragacanth. One reason for this change is 

 that many people and some health officers object to the use 

 of gelatin. They claim that it may be dangerous to health, 

 because it may have come from diseased animals, or it 

 may have been contaminated before or during the manu- 

 facturing process. Gum tragacanth is perfectly odorless 

 and is very satisfactory as a binder, even in very small 

 quantities. Stock may be made up as follows: "Dissolve 

 i ounce of gum in i quart of hot water; add 3 pounds 

 granulated sugar and mix thoroughly. This will produce 

 about one and one half quarts of gum tragacanth stock. 

 One quart of this stock is commonly used in making ten 

 gallons of ice cream. " 



Tragacanth l is the gummy exudation from plants be- 

 longing to the genus Astragalus, family Leguminosae. The 

 gum is in ribbon-shaped bands, i to 3 mm. thick, long and 

 linear, straight or spirally twisted. 



" Indian gum" 2 has its origin in other plants and is 

 usually found in lumps, never in ribbon-shaped bands. 



Because of this difference in physical characteristics, 

 adulteration of tragacanth with the cheaper Indian gum 

 is probably not attempted. But large quantities of gum 

 are sold in the pulverized form in which no physical dif- 

 ference can be detected. It has been found 3 that Indian 

 gum has a volatile acidity 7^ times as great as that of 

 tragacanth. Or expressed as acetic acid, Indian gum 

 contains about 15.8 per cent acetic acid and tragacanth, 

 2.1 per cent acetic acid. 



1 U. S. Pharmacopoeia. 2 U. S. Dept. of Agr., Bui Chem. Cir. 94. 

 3 U. S. Dept. of Agr., Bui. Chem. Cir. 94. 



