CHEMICAL CHANGES OCCURRING IN OYSTERS. 5 



Table 1. — Percentages of nitrogen obtained at various stages of handling. 





Amino-acid nitrogen. 



Ammoniacal nitrogen. 



Date. 



Shucker. 



Riffle. 



Commer- 

 cial 

 package. 



Refriger- 

 ator. 



Shucker. 



Riffle. 



Commer- 

 cial 

 package. 



Refriger- 

 ator. 



1914. 

 Oct. 5 



Per cent. 

 0.183 

 .173 

 .171 

 .148 

 .155 

 .1658 

 .1439 

 .1551 

 .1580 

 .1522 

 .1484 



Per cent. 

 0.166 

 .159 

 .1495 

 .149 

 .152 

 .1534 

 .1433 

 .1512 

 .1542 

 .1582 

 .1400 



Per cent. 

 0.128 

 .1267 

 .115 

 .106 

 .106 

 .1183 

 .1142 

 .1232 

 .1198 

 .1249 

 .1215 



Per cent. 

 0.120 

 .085 

 .146 

 .116 

 .089 

 .1237 



Per cent. 

 0. 00200 

 .00189 

 .00042 

 .00074 

 .00154 

 .0007 

 .0007 

 .00077 

 . 00038 

 .0000 

 .00032 



Per cent. 

 0. 0018 

 .0015 

 .0004 

 .0011 

 .0011 

 .0006 

 .0007 

 .0003 

 .0005 

 .0000 

 .0002 



Per cent. 

 0. 0012 

 .0015 

 .0000 

 .0000 

 .0004 

 .0007 

 . 00042 

 .00024 

 .0000 

 .0000 

 .00115 



Per cent. 

 0. 0025 



6 



.0004 



8 



.0010 



10 



.0022 



12 



.0000 



13 



.00077 



14 





15 



.1378 



. 00087 



16 





Nov. 9 



.1272 

 2. 0946 

 .1210 

 .1232 





10 



2.00024 





.00017 



11 



.1703 

 .1813 



.1670 

 .1692 



.1064 

 .1305 

 .1311 



. 00021 

 .00098 



.00007 

 .00021 



.0000 

 . 00073 

 .00073 



. 00073 



12 











16 







.1540 

 .1540 

 2. 1084 







. 00035 

















. 00035 



17 



.1932 



.1727 



.1318 

 .1429 

 .1204 

 .1142 



. 000S4 



.0002 



.00098 

 .00056 

 .0000 

 .00024 



2. 00031 







18 



.1635 

 .1652 



1. 1658 



.1585 

 .1630 

 1. 1429 

 2 . 1170 

 .1558 

 .1479 

 .1685 





. 00049 

 . 00014 

 1.00053 



.00011 

 .0000 

 i. 00025 

 2. 00025 

 .0000 

 .00007 

 .0000 





21 























Dec. 10 



.1739 

 .1456 

 .1702 



.1188 

 .1367 

 .1317 



.1177 

 .1177 

 .1250 



.00014 

 . 00035 

 .00014 



.00032 

 .00007 

 .00008 



.0000 



11 



. 00011 



12 



.00011 







1 Selects. 



2 Counts. 



From this table it is apparent that a considerable amount of 

 amino-acid nitrogen is present in the oyster as it comes from the shell. 

 It is probable that a certain percentage of amino-acid nitrogen exists 

 in the tissues of the oyster body, being either absorbed or formed in 

 the process of metabolism. Some of this may be due to bacterial 

 activity within the oyster itself. 



The comparatively slight washing of the oyster upon the riffle 

 board removes approximately 10 per cent of the amino acids present, 

 which shows that a certain proportion of them are present in the mucus 

 surrounding the oyster. An additional amount of approximately 

 25 per cent is removed in the washing and chilling process proper, 

 which may be explained partly by solution in the wash water, partly 

 by the fact that most of the remaining mucus is washed from the 

 outside of the oyster, and partly by the increase in volume of the 

 oyster due to osmosis. 



From the figures in the "Refrigerator" column it is seen that the 

 relative figures vary widely. In some cases the percentage of amino- 

 acid nitrogen apparently increased, in others remained constant, and 

 in still others decreased. This variation is due largely to difference 

 in stock used, as it was found impossible, in a large plant, to be sure 

 that the oysters stored were from exactly the same stock as those 

 analyzed in the preceding columns. However, if the amino-acid 

 content be taken as indicative of decomposition, it is evident that 



