THE SALTING OF FISH. 49 



the case of the split fish, for the blood would be almost entirely ex- 

 posed to view. The splitting would also greatly decrease the length 

 of the salting period, due to the more rapid penetration of the salt. 



SUMMARY. 



River herring, cleaned by various methods, were salted at very 

 high temperatures. All save those from which all roe, milt, and 

 blood had been removed spoiled. Perfectly cleaned river herring 

 were salted at a temperature of 88° F. It was concluded, therefore, 

 that the cliief cause of spoilage of fish during salting is the decom- 

 position of the blood remaining in the fish. The rate of penetration 

 of salts into skinned fish Avas compared with the rate of penetration 

 of salt into fish before skinning. It was found that salt penetrates 

 skinned fish at about double the speed it enters unskinned fish. This 

 proves the great value of splitting fish preparatory to salting. These 

 results are of great value in a j^ractical way, for they show that if 

 proj)er care be taken in the cleaning of fish, it is probable that they 

 may be salted in any hot weather anywhere in the United States. 

 With only an hour's extra work per thousand of river herring, these 

 fish may be prepared for salting in hot weather. The salt-fish prod- 

 uct prepared by this extra care in cleaning is of nuich better quality 

 than the commercial salt fish. 



IV. INFLUENCE OF FRESHNESS IN SALTING FISH. 

 INTRODUCTION. 



Staleness in fish is undesirable. However, more or lass staleness is 

 always unavoidable. It seems reasonable to suppose that during 

 colder weather staler fish may be salted than during hot weather. 

 Few data in the literature concerning the limits of freshness are of 

 value, for there are no standard methods of judging staleness. Most 

 writers on the subject have used various physical criteria to estimate 

 the relative freshness of stale fish. Some of the physical qualities 

 that have been used as criteria are : 1. The presence, or absence, of a 

 reddish discoloration on the ventral aspect of the backbone. 2. The 

 odor. 3. The manner in which the flesh separates from the back- 

 bone. 4. The appearance of the abdominal walls. 



The use of such criteria leaves too much to the judgment of the 

 investigator. In other words, the personal equation plays too promi- 

 nent a part. There are really but two ways of fairly stating the de- 

 gree of freshness of any fish. The first and most accurate w^ay is to 

 give the number of hours since the fish was caught and the temperar 

 ture at which it has stood for that time ; the other is to state its chemi- 

 cal analysis. The per cents of amino-acid nitrogen and of ammoni- 

 acal nitrogen are particularly indicative of the condition of the fish. 



In experiments previously described the number of hours the fish 

 had been out of the water before they were salted has be'en given 

 wherever possible. Since it was impossible to obtain live fish, stand- 

 ard freshness w^as considered as a fish transported in a boat at atmos- 

 pheric temperature for two hours. Then the fish were iced and 



