PROCESSING MARINE PLANT PRODUCTS 245 



ably more soluble in hot water than in cold. Four grades are produced: 

 bacteriological, medicinal, dental, and industrial. 



Algin: In this country algin is the phycocolloid manufactured in largest 

 quantity, accounting for more than half of the financial income from the 

 phycocolloids produced here. 



A significant factor is the ease of harvesting the seaweed from which 

 the algin is made, most algin being obtained from the giant kelp (Macro- 

 cystis pyrifera) obtained off the coasts of Central, Southern, and Baja 

 California. The beds of kelp are of large size, some being as much as 

 two square miles in area. The kelp grows in water from 30 to 90 feet deep. 

 The harvesting can be done mechanically. A large mowing machine, the 

 cutting bar of which is set about four feet below the surface of the water, 

 is operated from the front end of a motor-driven barge. As the kelp is cut, 

 it is brought aboard the barge by means of a conveyor. As much as 

 300 tons a day can be harvested in this manner. 



The giant kelp is a perennial. It lives 5 to 10 years and it can be 

 harvested three or four times a year. The annual production from Cali- 

 fornia is about 100 thousand tons. During World War II, four times this 

 quantity was taken so the beds are of a size that will permit expansion 

 of the industry. Kelp contains salts, laminarin, and manitol, which must 

 be separated from the algin. This separation is made on the basis that 

 alginic acid and the alginate salts of polyvalent metals are insoluble. 



The viscosity and gel properties of algin solutions depends on the tem- 

 perature, the acidity, and the addition of certain metalic salts. Algin 

 solutions can form films that are clear, tough, and flexible and that have 

 good adherent properties. These films are resistant to greases, oils, waxes, 

 and organic solvents but are compatible with the common hygroscopic 

 plasticizers, such as glycerine. 



These various properties of algin have made them useful in foods, 

 pharmaceuticals, and industrial applications. 



Carrageenin: Carrageenin contributes substantially to the income from 

 phycocolloids manufactured in the United States. It is produced from 

 Irish moss {Chrondrus crispus), which is obtained from Massachusetts 

 northward into Canada. Irish moss grows just above the low-water level 

 down to a depth of about 20 feet and is relatively easy to harvest. Usu- 

 ally, it is picked by hand or raked. An experienced man using a rake 

 having handles from 15 to 20 feet long can obtain as much as a half a ton 

 on a tide. The plants are gathered in bags and are sent to a central col- 

 lecting point for drying and baling. 



An important use of carrageenin is in the suspension of cocoa fibers in 

 the production of chocolate milk. Another important use is in the sta- 

 bilizing of ice cream, in which it stops wheying off, controls ice-crystal 



