178 U. S. BUREAU OF FISHERIES 



the canned products in general had a less pronounced odor and flavor 

 during early storage but the advantage seemed to disappear soon. 



The addition of cereal flours to brine used in the preparation of mild 

 cured and kippered salmon did not show any detectable improvement 

 in tlie quality of the product. On the other hand, canned Maine sar- 

 dines prepared from fish treated with salt and oat flour in the hold of 

 the boat diu'ing transit to the cannery showed some improvement over 

 those to which salt alone had been added. 



Spraying cereal extract on the surface of spiced herring resulted in 

 the treated samples having a definitely better odor and flavor than 

 the untreated samples after extended storage. 



Studies on these and other aspects of the possible utility of the 

 cereal flours is being continued by the research associates of the Musher 

 Foundation. 



STUDIES OF LACTIC ACID AS A POSSIBLE INDEX OF DECOMPOSITION IN 



FROZEN FISH 



In order to simplify understanding of the problem, decomposition 

 of fish might be classified into three general types. These are: (1) 

 Enzymatic decomposition, or the action of enzymes, already present 

 in the fish when alive, and which begin to break down the more com- 

 plex compounds in the fish into simpler substances; (2) the deteriora- 

 tion or oxidation of the oil in the fish; and (3) bacterial decomposition. 



When fish are frozen the bacterial action is arrested, since the 

 bacteria are almost entirely killed at freezing temperatures. However, 

 the other two types of decomposition in fish proceed but at a much 

 slower rate than if the fish were not frozen nor held at low tempera- 

 tures. The problem of rancidity or oxidation in fish is discussed 

 elsewhere in this report. Therefore, we are concerned here with enzy- 

 matic decomposition. It is known that one of the indications of the 

 action of enzymes in fish, immediately after death, is an increase in 

 the formation of lactic acid. Since lactic acid is a definite chemical 

 compound and its quantities in fish can be accurately determined by 

 analysis, our technologists decided that the amounts of lactic acid 

 formed in fish at various stages of decomposition might be used as a 

 reliable index of the progress, rate, or stage of decomposition or, to 

 put it another way, it might be an accurate means of measuring the 

 relative freshness of fish, somewhat similar to the use of the electro- 

 metric method for determining the relative freshness of fish, discussed 

 elsewhere in this report. 



Therefore, during the summer of 1937, \A'illis H. Baldwin, graduate 

 student assistant, was temporarily assigned to duty at the Maryland 

 State Marine Biological Station at Solomons Island, Md., for the pur- 

 pose of procuring and freezing samples of fish to be used in a study of 

 this project. It was necessary for the investigator to obtain these 

 fish himself so that he would have a complete history and control of 

 the fish from the time they were taken from the water until they had 

 passed through the progressive stages of chemical changes accompany- 

 ing decomposition to a point where they would be no longer fit for use 

 as food. In some instances, fish were actually taken from the water 

 alive and killed or were frozen, wliile alive, and the amounts of lactic 

 acid determined in each sample immediately after freezing. These 

 samples were then brought to our technological laboratory at College 



