458 U. S. BUREAU OP FISHERIES 



Reddening of cod has been studied by a number of scientists. 17 

 Research has shown that it is due to bacterial activity. There is 

 disagreement, however, as to whether it is caused by one or more 

 organisms. On the other hand, all investigators who have recently 

 studied the subject agree that the bacteria that cause reddening 

 grow best in strong salt (even saturated) solutions. Fresh water 

 kills them. A plentiful supply of air and moisture is necessary for 

 growth. At 50° to 55° F. growth is very slow. With increasing 

 temperatures, providing sufficient air and moisture are present, 

 growth increases, taking place most rapidly between 120° and 140° 

 F. The bacteria are killed when kept in dry air for 30 minutes at 

 248° F. m 



Experiments have shown definitely that the infection comes from 

 the use of salt obtained from sea water by solar evaporation. Salt 

 from underground mines is not infected. Examination has shown 

 that in most establishments the tanks, tables, floors, walls, and other 

 parts of the curing houses and rooms where the cured fish are 

 handled are more or less infected with reddening bacteria. 



The remedies suggested by Harrison and Kennedy 18 for diminish- 

 ing and preventing reddening follow : 



The most important point arising out of these experiments is the fact that 

 the tropical or solar salts carry the red organism, and so long as they are 

 used in their present form, red coloration of fish is bound to follow. 



Curing establishments that use this salt, or have been using it, have their 

 tanks, floors, storage places, puncheons, kench racks, carrying boxes, utensils, 

 etc., impregnated or inoculated with the red organism. 



Therefore, all measures taken to deal with this problem must provide for : 



1. A supply of salt free from the red organism. 



2. The destruction of the red organism in the curing factories wherever it 

 has infected buildings, utensils, etc. 



1. Recommendations regarding salt. — Mined salt of suitable size of grain 

 should be used until a supply of solar salt free from the red organism can be 

 secured. 



Importers of solar salt might sterilize this product by kiln heating. A 

 comparatively low dry heat is necessary — 100° C. for 30 minutes. 19 



2. Recommendations regarding cleaning of curing establishments. — -All curing 

 establishments which have used solar or tropical salts should clean and dis- 

 infect thoroughly all material which has come into contact with salt or fish. 



Steam, if available, may be used for this purpose. Puncheons, tanks, etc., 

 should be steamed inside and out, also all utensils, racks, etc. 



All parts of the factory that have become infected should be washed well 

 in fresh water. This will have two results : The removal of salt from wood- 

 work, thus preventing the organism from growing, and the fresh water causes 

 the disintegration of the red organism, breaking it down into a slimy mass. 



17 Preparation of the cod and other salt fish for the market, including a bacteriological 

 study of the causes of reddening. By A. W. Bitting. United States Department of Agri- 

 culture Bulletin No. 133, 63 pp., illus. (1911). Washington. 



Report of progress of biological inquiries. Report of the division of scientific inquiry 

 for the fiscal year 1920. By R. E. Coker. Appendix II, Report of the Commissioner of 

 Fisheries for 1920 (1921), pp. 27-28. Washington. 



Red discoloration of cured codfish. By F. C. Harrison and Margaret E. Kennedy. Re- 

 port 11, the Honorary Advisory Council for Scientific and Industrial Research (1922). 

 Ottawa, Canada. 



Red discoloration (so called "pink" or "pink eye") on dried salted fish. By P. C. 

 Cloake. Department of Scientific and Industrial Research, Food Investigation Board, 

 Special Report No. 18 (1923). London. 



18 Red discoloration of cured codfish. By F. C. Harrison and Margaret E. Kennedy. 

 Report 11, the Honorary Advisory Council for Scientific and Industrial Research (1922). 

 Ottawa, Canada. . 



19 At least one other investigator (Cloake) does not believe 212° F. is sufficient to 

 sterilize the salt in 30 minutes, and recommends 24S° F. Undoubtedly a much higher 

 temperature than either of these will prove more practical because of m'ore rapid 

 sterilization at the higher temperature. Salt can be heated to temperatures in excess 

 of 1.000° F. without bad effect, if desired. 



