76 MARINE PRODUCTS OF COMMERCE 



New Zealand. In 1939 government laboratories in New Zealand began to in- 

 vestigate the suitability of domestic seaweed as a source of agar. Four species, 

 Pterocladia lucida (R. Br.) J. Agardh, P. capillacea (Gmelin) Bornet and Thuret, 

 Gelidium caulacantheum J. Agardh, and Gracilaria confervoides, have been in- 

 vestigated (Moore, 1944). The first mentioned species is the principal source 

 because of its suitability and abundance. The properties of Pterocladia agar are 

 similar to those of its close relative, Gelidium, and it is satisfactory for bacteriologi- 

 cal culture media and other usual agar uses. There is some disagreement in the 

 literature as to the superiority or inferiority of its gel strength in comparison with 

 Japanese agar of commerce (No. 1 grade). 



From 1942 through 1949 over 100 tons, dry weight, of Pterocladia were col- 

 lected annually in New Zealand. Most of this raw material came from two areas: 

 the west coast of North Auckland and the Bay of Plenty. Most of the collecting 

 is done by the Maoris and most of the seaweed obtained is driftweed that would 

 decay along the shore if not gathered. Summer and fall are the principal seasons. 

 Collectors receive about one shilling per dry pound for good quality Pterocladia. 

 Since the yield of agar is about 25 per cent of the dry weight of the raw material, 

 agar production in New Zealand from 1942 through 1949 may have averaged up 

 to 25 tons per year, based on the collection data just given. 



Australia. Gracilaria confervoides has been used as a source of agar in Australia 

 since 1942. In 1945 production was about 2 tons per month (Wood, 1946), but 

 known supplies of raw material were adequate for a production goal of 100 tons 

 per year. 



Australian Gracilaria agar is said to have a lower gel strength in the lower 

 concentrations and a higher gel strength in higher concentrations (1.5 per cent 

 and above) than Japanese agar. Since Japanese agar varies widely, the compari- 

 son is a rough one. Australian agar is more elastic, usually gelling at a higher 

 temperature, 122-131° F (50-55° C), is more transparent, and exhibits greater 

 syneresis than Gelidium agar. It is similar to North Carolina Gracilaria agar in 

 these characteristics and is more suitable for industrial and food uses than for 

 bacteriological media. 



Australia's raw material is found along the east coast, especially in Moreton 

 Bay, Botany Bay, Middle Harbour, and Lake Woolaweyah on the Clarence River. 

 The plants grow from very shallow water to a depth of 20 feet and are attached 

 to stones and shells, often reaching a length of 2 feet or more. Harvesting is done 

 from the seaweed beds and driftweed is gathered along the shore after storms, 

 7 pounds of fresh seaweed are required (as compared to 10 or more in North 

 Carolina) for 1 pound of dry seaweed. The yield of such material is about 33 

 per cent if two extractions are made (Makarolf, 1946), nearly double the com- 

 mercial yield of the North Carolina and Florida species. Australian raw material 

 cost 5 to 10 cents per pound in 1945 and 1946. 



Australia's production process is similar to that used in the United States. About 

 96 pounds of water are used for each 4 pounds of dry seaweed. Centrifuges are 

 used to separate the agar solution and the seaweed residue; the resulting solu- 

 tion, after filtration, is concentrated by evaporation under vacuum. Thus, a higher 

 concentration is frozen. The following table shows how agar was used in Australia 

 in 1938. 



