244 FISHERY INDUSTRIAL PRODUCTS 



of commercial importance in the United States. Algin is produced from 

 brown seaweeds and agar and carrageenin from red varieties. The phyco- 

 colloids are used as thickeners, humectants, coagulants, bulking agents, 

 flucculation agents, and antibiotic carriers. 



These seaweed products have been able to pay the cost of harvesting 

 and processing because, being colloidal in nature, a small quantity pro- 

 duces a large effect, and they can be priced accordingly. Agar is valued 

 in the neighborhood of $3.75 a pound; algin and carrageenin are each 

 valued at about $1.25. Despite the higher price of agar, only one American 

 company has been able to survive foreign competition. There are several 

 companies producing algin or carrageenin. Altogether their output is 

 valued in excess of 10 million dollars a year. 



Agar: That the United States would be able profitably to manufacture 

 agar is an apparent paradox in that the Japanese can produce the product 

 more cheaply than we can. Fortunately, our product is of higher quality, 

 which is what keeps us in business. Financially, agar yields less income to 

 the United States than either algin or carrageenin. Nevertheless, it is a 

 product of great value to our nation. During World War II, it became of 

 considerable strategic importance, owing to its use as a solid culture me- 

 dium in bacteriology. The following unique combination of five properties 

 make it particularly valuable for this purpose : 



(1) Melted agar remains liquid at low temperatures of 32 to 39°C 



(2) This fluid has low viscosity 



(3) After being cooled below 32 to 39°C, the fluid changes to a gel that 

 remains semisolid at temperatures of 85 to 100°C 



(4) Agar is nearly transparent and is nearly neutral in reaction 



(5) Few common bacteria digest agar 



In addition to this very important use in bacteriology, agar also is used 

 for medicinal, dental, and industrial purposes. 



During World War II, some agar-producing seaweeds were harvested 

 on the coasts of North Carolina and Florida, but these areas have not 

 been able to meet competition in the post-war period. The principal 

 species of seaweed now yielding agar is Gelidium cartilagineum, which is 

 found along the coasts of Southern and Baja California. It grows on 

 rocks in fast-moving water and is harvested by divers. 



The harvested seaweed is washed in fresh water, dried in the sun to a 

 content of less than 20 per cent moisture (a higher content may result in 

 spoilage), pressed into bales of 200 pounds, bound with wire, and shipped 

 to the processor. Payment is made on the basis of agar content and gel 

 strength of the extracted agar. 



The process of manufacture is based on the fact that agar is consider- 



