AGAR AND RELATED PHYCOCOLLOIDS 65 



lichenoides, Ceramium rubrum, and Gelidium subcostatum. As the majority of 

 them yield an agaroid, they are used only as admixtures with G. amansii, or some 

 other superior raw material. Table 13 lists what may be an ideal mixture of various 

 seaweeds for making one batch of agar. 



Table 13. Ideal Proportions of Various Japanese Seaweeds for One Batch, 

 According to the Japan Agar Distribution Control Company.' 



Species Per cent 



Gelidium amansii 45 



Gelidium japonicum 10 



Acanthopeltis japonica 5 



Ceramium hypnaeoides 10 



Gracilaria confervoides 15 



Ceramium rubrum 5 



Gelidium subcostatum or G. tenue 10 



Harvesting Methods. Gelidium amarvsii occurs from the intertidal zone to a depth 

 of 60 feet or more, the best beds being located in deeper water. Since the plants 

 grow firmly attached to rocks, they must be pulled off by hand or by means of 

 special rakes. Most of the Gelidium is gathered by hand by divers, wearing goggles 

 or, in deeper water, full diving suits. Fishermen and their families are issued sea- 

 weed collecting rights by a Central Federation of Fishermen's Cooperative Associa- 

 tions, which gives individuals or local associations exclusive rights to specified areas 

 (Adams, 1947). The harvesting season is from April to September. 



Freshly gathered seaweed is spread to dry on bamboo racks along the shore. 

 Partial bleaching occurs if the seaweed is sprinkled with fresh water or rained 

 upon after it has been once dried. When dry, it is stored in sheds or barns where it 

 can be kept indefinitely. 



Japanese Factories. There are approximately 600 small agar factories in Japan, 

 most of which operate only from early December to about March 1, with an 

 average of 70 production days per annum. The average factory produces from 

 75 to 125 pounds of agar per day. The largest Japanese factories produce about 

 10,000 pounds per year. 



Japanese agar factories are small because of the lack of machinery and cheap- 

 ness of labor. The majority are located in the cool highlands of central and 

 northern Japan, where the air is dust-free and winter weather such that agar gel 

 will freeze when placed outside. Only a few factories are equipped with mechan- 

 ical freezing machinery. 



Processing Methods. Dried seaweed is shipped by rail from coastal areas to 

 processing plants. A batch to be extracted is soaked in cold water in outdoor 

 concrete vats to effect bleaching and cleaning. Further cleaning and washing are 

 done in a vat in which the seaweed is pounded by mallets attached to an over- 

 head eccentric shaft to remove calcareous incrustations and shells. Some factories 

 are equipped with washing machines. 



The desired mixture of various seaweeds, totalling 200 to 500 pounds, dry 

 weight, is added to a tank of boiling water heated by a brick firebox in which 



* Adams, C. M., "The Japanese Agar-Agar Industry," U. S. Fish and Wildlife Service, 

 Fishery Leaflet, 263 (1947). 



