CHEMICAL CHANGES OCCURRING IN OYSTERS. 



13 



Table 5. — Average values of amino-acid nitrogen and total solids of oysters washed 



by both methods. 



(Shell stock, 100 per cent.) 



Determination. 



Old 

 method. 



New 

 method. 



Shucker: 



Amino-acid nitrogen 

 Total solids 



Commercial package: 

 Amino-acid nitrogen 

 Total solids 



Per cent. 

 104.8 

 109.4 



95.0 

 94.0 



Per cent. 

 106.2 

 107.3 



72.2 

 76.0 



Considering the comparatively small number of determinations 

 made, and the multiplication of error involved in expressing the 

 various fractions as percentages, the figures in Table 5 are very 

 satisfactory checks. They show that in the old method of washing 

 the finished product contains, in a given volume, about 94 per cent 

 of the food value possessed by the same oysters in the shell, whereas 

 in the modern method of washing this figure falls to a percentage of 

 about 74 per cent. 



This series, however, does not indicate in any way the cause of the 

 loss, as the amino acids disappear at the same rate as do the total 

 solids. This loss may be due almost entirely to osmosis, or it may 

 be due in part to solution in the wash water of soluble parts of the 

 oyster, or to both. That there is a loss of soluble matter in the wash 

 water there is no doubt. This is proved by the complete disappear- 

 ance of sodium chlorid after a comparatively short period of washing. 

 Sodium chlorid and other crystalloids would wash out much faster 

 than the soluble protein compounds, which are colloids, but if the 

 sodium chlorid disappears it is certain that other soluble constituents 

 tend to disappear also. 



SERIES V. 



In order to determine, if possible, just what proportion of the 

 apparent loss of the various constituents is due to osmotic distention 

 and what proportion is due to solution in the wash water, and also 

 the general chemical effect of all kinds of oyster washing, a series of 

 experiments was run in which measured volumes of oysters were 

 subjected to various washing processes and were both measured and 

 analyzed at various stages of washing. The results of this series are 

 given in Table 6, and a mathematical analysis of the results obtained 

 is given in Table 7. 



Experiment 1. — Five gallons of standards were taken from the 

 chute immediately before they entered the agitation tank, carefully 

 measured, put into an equal volume of water, stirred thoroughly, 

 and allowed to stand. Measurements were made of both water and 

 oysters every 6 hours for the first day, and every 12 hours thereafter 

 for 3 days. The water was renewed after each measurement. Chem- 

 ical determinations were made once a day upon samples taken in the 



