AGAR AND RELATED PHYCOCOLLOIDS 51 



small squares and warming them over a charcoal fire. One side of the square is 

 then dipped into a flavored soy sauce and a portion of steaming rice placed on it. 



Food Value of Edible Algae. Seaweeds are a poor source of energy for man- 

 kind because a large portion of the calories they contain are in an indigestible 

 form ( complex carbohydrates ) . Even in parts of the world where seaweeds are 

 widely eaten, they are not a principal energy source, but are consumed along with 

 more substantial foods. While they appeal to the oriental peoples as a delicacy, 

 their nutritional value depends upon their vitamin and mineral content. The 

 vitamin C content of some seaweeds has been shown to equal or exceed that of 

 lemons (Norris, Simeon, and Williams, 1937), while the Bi content compares 

 favorably with that of many fruits and vegetables. In general the shallower the 

 water in which an alga grows, the higher its vitamin C content, while the propor- 

 tion of vitamin Bi does not vary with depth. Vitamin C also varies with the sea- 

 son; in most cases it is highest during the warmer months or toward the latter part 

 of the best season of growth (Lunde and Lie, 1938). 



The genus Porphyra, from which nori or laver is prepared, was found to contain 

 up to 140 mg of vitamin C and over 500 Sherman units of vitamin Bi per 100 gm 

 of fresh weight, the highest of any seaweeds tested. It is also a good dietary source 

 of iodine, required for normal function of the thyroid gland. Another seaweed 

 that is high in vitamin C content, especially in the fall, is Rhodymenia palmata 

 (L.) Greville, from which the edible seaweed product dulse is made. Table 9 

 gives vitamin Bi and C contents of a number of the common algae. 



Table 9. Vitamin B^ and C Content per 100 G Fresh Weight of 

 Some Common Seaweeds.* 



Rhodymenia palmata is used extensively in Scandinavian countries as a feed 

 for cattle and sheep. These animals graze selectively on Rhodymenia when it is 

 available at low tide. Farmers along the coasts gather Rhodymenia and sometimes 



* Data compiled from Lunde and Lie (1938) and Norris, Simeon and Williams 



(1937). 



