Changes in Numbers of Histamine-Metabolic Bacteria and Histamine Content during Storage of Common Mackerel

Abstract

The accumulation of histamine during the storage of fish meat does not depend only on histamine-forming bacteria but also on histamine-decomposing bacteria. To clarify the mechanisms of histamine accumulation, changes in the numbers of both histamine-decomposing and histamine-forming bacteria and histamine contents were examined during the storage of common mackerel at 5 and 30°C for two months each throughout the year. In the case of samples stored at 5°C, the histamine contents, once accumulated, decreased and disappeared when the sample putrefied as histamine-decomposing bacteria took over (more than 106 cells/g) and the pH value became neutral. At 30°C storage, the histamine content did not always decrease, suggesting that the histamine-decomposing ability of the bacteria might therefore be inhibited at 30°C.