260 BULLETIN 1022, U. S. DEPARTMENT OF AGRICULTURE. 
aya 
20° and processed at 116° and 121° C., respectively, the pronounced 
and repeated bulging of the cans masks this effect. The decomposi- 
tion of the material under test, if such is the explanation, is less 
marked than in the string beans, but is 
nevertheless exhibited. 
The relation of blanching to the devel- 
opment of pressures is clearly shown by | 
the comparison of the curves for the 
blanched and the unblanched peas sealed 
at low temperatures and processed at 116° 
C. Approximately 11 pounds greater — 
pressure was developed in the can of un- 
blanched material. 
In the work with peas it has been ob- 
served that the stage of maturity, the 
amount of blanching, and the fullness of 
the can have more or less effect upon the 
pressure developed. The influence of 
these factors is not here illustrated with 
curves, however. | 
The maximum pressures attained dur- 
ing the period of processing used in these 
tests (60 minutes) were slightly below the 
theoretical values, but above those for dis- 
tilled water. 
IN POUNOS PER SQUARE INCH 
Pressure 
6 
TIME IN MINUTES 
Fig. 14.—Experimential time- 
pressure curves for peas in 
No. 2 tin cans sealed at differ- 
ent uniform temperatures and 
processed at 100°, 116°, and 
121° C.; 400 grams of peas, 
170 ec. ec. of liquor. Curve 
for can sealed: A, At 20° C. 
and processed at 100° C.; a, 
at 20° €. and processed at 
11G2S Cee ae atm20- SC and 
processed at 121° C.; a’’, at 
19° C. and processed at 116° 
C., peas unblanched; B, at 
70° C. and processed at 100° 
Co 20S at (0 > © and? proce 
essed) ata el625C. 5 bso te Or 
C. and processed at 121° C.; 
C, at 80° C. and processed 
at 100° C.; c¢, at 80° C. and 
processed at 116° C.; ¢’, at 80° 
C. and processed at 121° C. 
VACUUM STUDIES. 
The vacuum readings made on the cans 
used in the pressure tests gave results en- 
tirely comparable with those for string 
beans. The vacuums obtained were some- 
what below the theoretical values and 
slightly above those for beans. The effect 
at the higher temperatures was again ob- 
served, the reading in the case of the cans 
processed at 116° and 121° C. being lower 
by approximately 2 inches than those proc- 
essed at 100° C. 
Those factors which affect the develop- 
ment of pressure in peas likewise influence 
the vacuum. The amount of blanching, 
the maturity of the peas, the liberation of gases during processing, the 
bulging of cans, and the individual variations in the resistance of 
cans to external pressure all affect the vacuum readings. | | 
