112 REPORT OF THE SECRETARY OF COMMERCE 



commercial application of tlie electrometric method for determining 

 the relative freshness of such nonoily fish as haddock developed sev- 

 eral years ago by members of the Bureau's technological staff. Conse- 

 quentl}^, one of the Bureau's technologists was assigned to the labora- 

 tories of a large fishery producer, and, as a result, equipment has been 

 designed which is as nearly automatic in operation as is possible and 

 which enables the oj)erator to make determinations upon 10 samples 

 ■of fish at one time. In this way rapid tests for the freshness of fish 

 purchased can be made without delaying packing activities or other 

 commercial operations. At the present time this test is being used by 

 this firm for the selection of fish which are to be used in fancy packs 

 of quick-frozen products. These products are expected to remain iii 

 good condition over a longer period of time than is ordinarily expected 

 where the fish are not selected for their prime condition. One of the 

 'Changes occurring in fish immediately after death is an increase in 

 the formation of lactic acid, which progresses for some time after 

 death. Bureau technologists have begun a study of this formation of 

 acid as a possible reliable index of the rate of decomposition in frozen 

 fish. 



Certain species of salmon undergo considerable apparent physical 

 •change during the course of the canning season and the quality and 

 value of the canned product is at present judged somewhat on this 

 basis. The Bureau has undertaken a chemical study of these changes 

 in tlie hope of determining their true significance. In studying the 

 characteristics of the oil in canned salmon, it was found that those 

 for each species fell between quite definite and more or less separated 

 1 units. Regulatory bodies have shown interest in these data as a 

 possible help in identifying the species of salmon after it is canned. 

 During the year the Bureau published a report covering an investi- 

 gation on the preservation of Pacific oysters. The information ob- 

 tained during tne conduct of this work has been helpful in the begin- 

 ning of a new oyster-freezing industry in the Pacific Northwest. 

 During the past year experiments have i3een continued in developing 

 methods for canning fishery products, both in the home and for appli- 

 cation on a commercial scale. 



Bacteriological studies. — Since the preservation of fish is based on 

 the prevention of spoilage through bacterial action, any device or 

 method which can be found to serve this purpose is vitally important 

 to both the fishing industry and ultimate consumer. Studies on other 

 food products indicate that the use of ultraviolet light rays have been 

 beneficial in lowering the number of spoilage bacteria in milk, meats, 

 bread, etc., thus improving the quality of these foods. Late in 1937 

 the Bureau's bacteriologists began a study of these ultraviolet light 

 rays in reducing the bacterial count of various fishery products. 

 While this investigation is not yet completed, it has been found that 

 the rays will kill marine bacteria, and we hope to work out a practical 

 and connnercially feasible application of this method in the treatment 

 of fishery products. 



Pharmacological studies. — In recent years scientific investigators 

 have recognized the increasing importance of the role of minerals in 

 foods and in feedstuffs for farm animals. Certain minerals have 

 been found to be essential in nutrition, and it has been clearly dem- 

 onstrated that there is need for a better understanding of other 



