FISHERY INDUSTRIES OF THE UNITED STATES, 1932 155 



IMPROVED METHODS FOR SMOKING FISH 



The control of temperature, humidity, and smoke in smoking fish 

 has been appHed to tlie preparation of finnan haddie on a semicom- 

 mercial scale. It has been found possible to reduce the loss of mois- 

 ture to a considerable extent by employing: a comparatively low tem- 

 perature and a relatively high humidity in the smokehouse. At a 

 temperature of 100° F. and a relative humidity of approximately 60 

 percent, it has been shown that finnan haddie can be produced con- 

 taining an average of 72 percent moisture. This moisture content is 

 5 to 10 percent higher than the average commercial product, and 

 means considerable saving to the smoldng firm in that it reduces their 

 losses. 



BACTERIOLOGICAL STUDIES 



During the past year Francis P. Griffiths, bacteriologist of the 

 Division, continued studies at the Gloucester laboratory of the rela- 

 tion of bacteria to the preservation of fish. As a result of his studies 

 it has been found that formaldehyde contained in the smoke has but 

 very slight preservative effect upon light smoked finnan haddie for 

 the reason that the concentration is so low. While brining the fish 

 before smoking adds to the flavor, it has been found that its preser- 

 vative effect also is practically negligible. This may actually become 

 a source of infection, depending upon the type of salt employed in the 

 preparation of the brine. 



The effect of the rate of freezing and temperature of storage upon 

 the survival and growth of bacteria usually found on haddock fillets 

 has been investigated hj Mr. Griffiths, and work is being extended to 

 include several pathogenic bacteria in the tests. In conjunction v^dth 

 the research cited previously dealing with the relative freshness of 

 fish, Mr. Griffiths also made numerous tests to correlate a chemical 

 test for freshness with the bacterial count of the fish flesh with very 

 encouraging results. 



PRESERVATION OF FISHERY BYPRODUCTS 



During the past year the research in connection with the preserva- 

 tion of fishery byproducts carried on at the Gloucester technological 

 laboratory has been a continuation of the projects outlined in the 

 report of the Division for 1931. This was carried on by Roger W. 

 Harrison, with the assistance of Andrew W. Anderson and S. R. 

 Pottinger. 



IMPROVED METHODS FOR MANUFACTURING FISH MEAL FROM NONOILY 



FISH WASTE 



The utilization of waste from the preparation of packaged fishery 

 products, especially ground fish, has an important bearing upon both 

 the fishing and agricultural industries, for the conversion of this waste 

 into a useful product such as fish meal brings added revenue to the 

 fishing industry and brings to agriculture one of the most highly 

 nutritive protein concentrates obtainable. As a service to these in- 

 dustries, it is pertinent that the fundamental factors of manufacture 

 as related to the preservation of nutritional value be fully understood 

 and, further, it is also of primary importance to obtain information 

 as to the most economical means of obtaining this end. The studies, 

 therefore, have been carried on with these aims in mind. 



