44 



The coaqulable protein nitrogen was determined in a sample of 200 cc of the water 

 extract This was placed in a 300 cc evaporating dish and evaporated on the steam 

 bath to a volume of 40 cc. The solution was neutralized with tenth-normal sodium 

 hydroxid, using phenol phthalein as indicator, then replaced on the steam bath and 

 allowed to evaporate for ten minutes, filtered on a plain filter, and washed with hot 

 wat or. The filter and precipitate were transferred to a Kjeldahl flask and the nitrogen 

 determined. 



\nrido nitrogen: The coagulable protein filtrate was made up to 100 cc volume and 

 5<f cc employed for the amido nitrogen determination. The 50 cc were placed in a 

 cc graduated flask, 15 grams of sodium chlorid added, and the flask well shaken 

 laced in an ice box. A 24 per cent solution of tannin was prepared, filtered, and 

 placed in the ice box. After one hour 30 cc of the 24 per cent tannin solution were 

 added to each flask and the two flasks filled to the mark with ice cold water. The 

 flasks were thoroughly shaken and stood in the ice box over night. A blank must be 

 carried out simultaneously, as the best tannin contains some nitrogen. The solutions 

 an- filtered into 50 cc flasks and the nitrogen determined in the 50 cc. The nitrogen 

 liirure thus obtained multiplied by two, minus the nitrogen of the blank, gives the 

 amido nitrogen in 50 cc of the coagulable filtrate. 



The sum of the amido and coagulable nitrogen subtracted from the total soluble 

 nitrogen is considered as proteoses and peptones. No effort was made to separate the 

 albumoses, proteoses, and peptones. All the results are calculated to a moisture and 

 fat-free basis and are also expressed in per cent of the total nitrogen of each day's 

 analysis. 



The ice water extractions were made by Mr. H. L. Amoss and the coagulable and 

 amido nitrogen separations by Mr. F. C. Cook, both of the Bureau of Chemistry. 



The methods as selected, while not representing all that might have been employed, 

 were those that have been generally used in the Bureau of Chemistry, and it is hoped 

 that the work may be used as a starting point in this subject and serve to show the 

 accuracy of the methods when.applied to meats in a progressive state of deterioration. 



DISCUSSION OF RESULTS. 



The moisture results show very little change throughout the period, the average 

 in the case of the fresh and preserved samples being 73.00 and 71.70 per cent for 

 the storage sample. There was 4.12 per cent of fat in the fresh chicken and 4.09 per 

 cent in the storage. The results on total nitrogen (see table, page 48) are as uniform 

 throughout as the nature of the material and the accuracy of sampling would permit, 

 and serve to show that there is no gaseous loss of nitrogen, while the ammonia nitrogen 

 (that determined directly on the sample, as well as that determined in the extract) 

 is markedly increased throughout and very uniform, particularly in the case of the 

 stored and preserved samples. The amount is quite small at the time of the first 

 analysis and remains so till the third analysis (made after standing two days), when the 

 storage sample contains a little more than the other samples. From this point the 

 increase is rapid. The variations in percentage amounts are from practically 1 per 

 cent in all cases on the first analysis, to 11, 15, and 13 per cent for the fresh stored and 

 preserved samples, respectively, on the last analysis, after seven days standing. The 

 ammonia results on the water extract were unfortunately not made on the first 

 day. They show practically the same results as those determined directly, but are 

 not quite so uniform and not so high in amount. In the case of the formation of 

 ammonia, the increased amount seems to begin to be formed after two days standing. 



In connection with these changes it may be well to state here the changes in the 

 samples which could be observed macroscopically. At the time of first analysis the 

 samples were fresh, the storage sample showing a characteristic dried appearance. 

 After standing one day they were practically the same, though what may be termed a 

 slight fermenting action seemed to be taking place. On standing two days the samples 

 had begun to deteriorate, especially the fresh and stored sample, while the preserved 

 sample appeared fairly fresh. After three days standing, the deterioration was more 



