Histamine has been suspected to be responsible for the outbreak of gizzard erosion in the chicks fed on fish meal diet. To obtain innoxious products, the behavior of histamine which accumulated in the raw fish was examined over the whole process of fish meal manufacturing. Frozen sardine, or mackerel was allowed to stand at room temperature in summer (average ca. 30°C) for different periods to obtain fresh or putrefied raw fish. Each raw fish was treated by the pilot plant of wet process with rotary dryer. Then the intermediate products (press cake and stick water) and the products (ordinary meal, whole meal and fish solubles) obtained were analyzed along with the raw fish. For the evaluation of “whole meal” process, a box type dryer was also used.
As a result, significant decrease in histamine was observed in every heating process involved in the fish meal manufacturing, namely cooking of raw fish, drying of the press cake with or without addition of fish solubles, and concentration of stick water. These decrease in histamine may result from chemical changes of histamine induced by heating in the presence of carbohydrates or proteins rather than from physical loss or microbiological decomposition. The resultant substances may be causative of gizzard erosion.