698 
Journal of Agricultural Research 
Vol. V, No. is 
Table XI .—Rate of formation of proteoses , peptones , and amino acids in trypsin-sodium- 
carbonate solution —Continued 
QUANTITY (in CUBIC CENTIMETERS) OP Njs ALKALI PROTEINATE NITROGEN 
Experiment No. — 
Digestion period. 
26 
25 
27 
28 
30 
3i 
32 
34 
Beef sam¬ 
ple 8. 
Veal sam¬ 
ple 8. 
Beef sam¬ 
ple 8. 
Veal sam¬ 
ple 8. 
Skim-milk 
sample 2. 
Veal sam¬ 
ple 9. 
i 3 « 
fljj 
n 
) 
8 a 
>■ 
Beef sam¬ 
ple 10. 
Veal sam¬ 
ple 10. 
Beef sam¬ 
ple 10. 
Veal sam¬ 
ple 10. 
Beef sam¬ 
ple 11. 
Veal sam¬ 
ple 11. 
Beef sam¬ 
ple 12. 
Veal sam¬ 
ple 12. 
Hours. 
2. 
5*9 
3-7 
6.2 
5 -i 
2.9 
3 -o 
3-6 
3 -o 
3*2 
3 -i 
2.8 
3-5 
3*7 
4*9 
4.8 
5 *i 
6. 
5 -o 
7 -o 
5-2 
6-5 
•9 
3-6 
.0 
5-1 
3-9 
3-9 
4-5 
S*o 
3*7 
3*8 
2*3 
3*5 
Age of meat 
...days.. 
8 
8 
3 i 
31 
6 
21 
19 
19 
28 
28 
19 
19 
8 
8 
Trypsin 
used, gm.. 
1 
1 
2 
2 
2 
2 
2 
2 
4 
4 
2 
2 
4 
4 
4 
4 
Trypsin No. 
2 
2 
i 3 
2 
2 
2 
2 
2 
2 
2 
3 
3 
3 
3 
3 
3 
It is obvious that the amino nitrogen contained in the digestion fluid and actually 
determined was the sum of the amino nitrogen derived from (1) the trypsin; (2) the 
nitrogenous extractives, both of which were present before digestion began; and (3) 
the amino groups unlinked by the cleavage of the more complex proteoses into the 
simpler peptones and polypeptids. This is brought about by the action of the trypsin- 
sodium-carbonate solution during the digestion process. The results actually obtained 
in the determinations were diminished by the sum of 1 and 2, so that the figures in 
Table XII correspond to 3, or the amino nitrogen actually formed by the digestion. 
The minus quantities obtained in this way in some of the experiments for the 
15-minute digestion period are probably due to the fact that the errors in determin¬ 
ing the small amounts of amino nitrogen in 1 and 2 are large when compared with 
the small amount formed during 15 minutes’ digestion. 
DISCUSSION OF THE DIGESTION EXPERIMENTS 
Theoretical maximum. —If the digestion of the meat by trypsin could 
be brought to completion, the meat proteins would be split into simple 
amino acids. Such a complete cleavage of protein by a trypsin sodium- 
carbonate solution seldom, if ever, occurs. One reason is that the action 
of the trypsin becomes slower and slower the nearer the digestion process 
approaches completion. But by boiling the meat with hydrochloric 
acid, as already described (p. 678), the proteins and other nitrogenous 
substances are completely hydrolyzed, or 100 per cent digested. The 
data in Table XII, under the heading “Theoretical maximum/’ were ob¬ 
tained from Table V. The total amino nitrogen obtained from hydro¬ 
chloric-acid hydrolysis minus the amino nitrogen in the extractives gave 
the figures recorded in Table XII. A slight error was here involved; the 
correction should have been the amino nitrogen in the extractives after 
acid hydrolysis, not before. For the present purposes this error is 
regarded as entirely negligible. 
