AGAR AND RELATED PHYCOCOLLOIDS 



61 



moss or dehydrated extractive in water. Dissolution in cool water without the 

 aid of heat can be accomplished if powdered carrageenin ("Krim-Ko" gel, for 

 example) is dispersed in the desired volume of water and then sufficient acid 

 added to reduce the pH to below 6.0 (Stoloff, 1950). Approximately 4 ml of 

 O.ION acid is required for every 2 gm of "Krim-Ko" gel. It will cause immediate 



Fig. 5-8. The gel strength of a 

 2 per cent solution of Irish moss 

 extractive with various concentra- 

 tions of potassium chloride. {Data 

 from L. Stoloff) 



20 40 60 80 1.00 1.20 

 KCL PERCENT BY WEIGHT IN SOLN. 



solution. Sufficient alkali to neutralize the acid may then be added. Solutions pre- 

 pared in this manner are very clear and will gel only when high concentrations 

 are used. Addition of salts, sugar, glycerin, or alcohol should be avoided until the 

 gel powder has dissolved; after solution has occurred, it will result in an increase 

 in viscosity. If a relatively high concentration of solute is added, the extractive 

 may develop a pasty consistency. Carrageenin solutions prepared by this method 

 exhibit all the useful thickening, emulsifying, and suspending properties obtained 

 with hot process solutions. It is believed that salad dressings, rehshes, and all 

 sauces that contain vinegar may be stabihzed more easily by this new method. 

 Irish moss extractive may now be added to mixtures that cannot be heated. 



The viscosity of liquid solutions of carrageenin varies, as do other hydrophilic 

 colloids, with concentration and temperature. In addition viscosity of carrageenin 

 solutions varies with the manufacturing process, with the procedure used to 

 dissolve the extractive, with previous treatment of the solution, and indirectly 

 with the concentration of various other solutes present. As a result the range of 



