REFRIGERATION OP FISH 537 



given in a work of this scope. Fish that are panned and frozen in 

 cakes are sorted during the panning operation. Fish that are frozen 

 singly, like halibut and salmon, are sorted after the glazing operation. 

 In private freezers (especially for salmon and halibut on the 

 Pacific coast, where the fish are purchased by the freezer) the fish 

 are next weighed. For this purpose, two-wheel carts are provided, 

 with the body lined with galvanized sheet iron and with the forward 

 end sloping outwardly so that when dumped the fish slide out with- 

 out violence. These carts are tared; with their load of fish they 

 are rolled upon the scale platform and weighed. 



DRESSING AND CLEANING 



Fish freezers generally do not make a practice of dressing fish 

 before freezing. In some cases this is done, especially in salmon. 

 The salmon are dumped into a washing tank with fresh water run- 

 ning continuously. They are taken from the tank, beheaded, and 

 gutted. The slit in the belly is sometimes made so as to leave the 

 napes of the two sides connected (that is, the shoulder girdle bones 

 are not separated). This prevents the fish from spreading open. 



The belly membranes are rubbed out and the kidney (bloody organ 

 in the belly cavity running along the backbone) is removed. For 

 this work the operators use cotton gloves. In some instances hand 

 brushes are used. The importance of removing the kidney and 

 blood is overlooked frequently. It has been found that the blood 

 of fish decomposes much more readily than the flesh of fish. If all 

 the blood is removed carefully the fish will keep much better than 

 it will if some blood is left. It is impossible to remove all blood if 

 the kidney is left in the fish. 



In public freezers fish usually are frozen as received — sometimes 

 gutted, sometimes not, Salmon, halibut, and haddock always are 

 gutted, and usually also medium and large bluefish, weakfish, and 

 lake trout; mackerel, eels, smelt, butterfish, and the smaller pan fish 

 are usually frozen round. 



Apart from the desirability or unclesirability of gutting as a trade 

 practice, it deserves and has received some consideration as a ques- 

 tion of sanitation and keeping quality. Green 25 investigated the 

 subject; the following extracts from her memoir show her results: 



(a) Physical examination. — Altogether about 50 gutted and ungutted fish 

 were examined carefully, externally and internally, and comparisons made. 

 Each fish was cut down the length of the spine and opened out like a kipper 

 for inspection. Little difference in external appearance could be detected be- 

 tween gutted and ungutted fish, but much difference was apparent internally. 

 Comparisons were best made after the fourth day at ordinary temperature. 



The flesh of the ungutted herrings was still fairly white, firm, and in most 

 cases free from any putrid smell. The muscle tissue immediately round the 

 spine was inclined, on the whole, to be more bloodstained than was the case 

 with the gutted ones, but in spite of this the flesh was firmer, whiter, and in 

 better condition. 



The flesh of the gutted ones, on the other hand, was much yellower and 

 more discolored although not so bloodstained down the spine. They also 

 had a very strong oily smell, which was completely lacking in the ungutted 

 ones ; in fact, the general appearance and smell of them was not nearly so 

 good. 



25 lone H. Green, " Report of experiments on the cold storage of herrings carried out 

 at North Shields [June and July, 1919]." Department of Scientific and Industrial 

 Research, Food Investigation Board, Memoir No. 11, 6 pp. London, 1920. 



