Abstract
Much attention has been given to discoloration of oil on fishery products, and it has been pointed out that the reaction between carbonyls in oxidized oil and volatile basic nitrogenous substances resulted in discoloration of oil.
Present paper is concerned with the influence of bacterial growth on discoloration of oil. The authors found that discoloration is promoted by the bacterial growth, and differences in its intensity are observed according to the species of bacteria, among which those of Vibrio, Micrococcus and Bacillus are the most active. In this case, the intensity of discoloration is proportional not to volatile basic nitrogen contents but to peroxide value. Moreover, development of strong discoloration by autoxidation of oil under a sterile condition after longer period than after the periods under existence of bacteria shows that volatile basic nitrogenous substances produced by bacteria are not essential to discoloration of oil. It is therefore reasonable to conclude that discoloration of oil by bacteria is promoted not by production of volatile basic nitrogenous substances but by acceleration of oil oxidation.
