FISHERY INDUSTRIES OF THE UNITED STATES, 1934 83 



PRESERVATION OF FISHERY PRODUCTS FOR FOOD 



Experimental work during the past year in the preservation of 

 fishery products for food was conducted at the (Jlloucester hiboratory 

 by James M. Lemon, teclinologist in charge, assisted by Francis P. 

 GriHiths, bacteriologist, and Maurice E. Stansby, chemist, and at the 

 Washington laboratory by Norman D. Jarvis, technologist in charge 

 of canning work. Duiing the latter quarter of the year, Mr. Griffiths 

 was detailed to conduct a series of cooperative bacteriological experi- 

 ments at the food ])roducts laboratory of the Massachusetts State 

 College, Amherst, Mass. 



HANDLING FRESH MACKEREL 



Mackerel is an extremely delicate fish and is easily bruised and 

 crushed during packing and in shipment. For this reason special 

 care is needed in the handling of this fish so that it will arrive at the 

 market in good condition. One of the methods employed by the 

 imlustry to overcome this difficulty is "floating," which consists of 

 packing the mackerel in a watertight barrel with sea water and ice. 

 In some cases, the sea water is drawn from the harbor under the 

 packing plant, where it is more or less contaminated. While this 

 method of packing retards bruising and crushing, it leads, in many 

 cases, to decomposition of the mackerel en route to market, with 

 consequent loss to the industry. In order to aid in minimizing these 

 losses, a series of tests were conducted to develop a method for packing 

 and shipping this fish which would have promise of commercial appli- 

 cation. As a result of this work, it was found that when fresh mack- 

 erel were eviscerated, washed in clean water, and packed in boxes 

 with finely crushed ice, a better product could be placed in the hands 

 of consumers than with the "floating" method. 



While this method is superior to the commercial method of 

 "floating", it still is not ideal, as water from the melting ice has a 

 tendency to leach the minerals from the fish. 



STORAGE OF FROZEN MACKEREL 



When frozen mackerel have been held in cold storage for a certain 

 period, there is a tendency for the oil or fat in the fish to become rancid, 

 thereb}' making the mackerel unfit for sale. In order to aid in cor- 

 recting this condition, a series of experiments were conducted on the 

 relationship between temperature of storage and the development of 

 rancidity in mackerel oil, the action of enzymes on mackerel oil, and 

 the seasonal variation in the oil content of mackerel. While these 

 experiments have not progressed to the point where final results can 

 be reported, they reveal that the percentage of oil in mackerel flesh 

 varies from 2 to 5 percent from early spring catches to nearly 30 

 percent in the August catch, then declines to about 10 percent in the 

 December catch. This study further showed that the development 

 of rancidity is more or less directly correlated with the oil content. 

 This would indicate that mackerel of low oil content, that is, those 

 caught during the early spring, would be less apt to develop rancidity 

 in cold storage. However, economic factors may tend to neutralize 

 some of these benefits, for mackerel commands a relatively high price 



