26 
BULLETIN 1265, U. S. DEPARTMENT OF AGRICULTURE 
found true. In no instance was the natural color better preserved in 
the scalded or precooked corn than in that which was untreated. 
EFFECT OF PRECOOKING CORN ON PRESSURE AND VACUUM. 
In the bulletin (38) previously mentioned, the writers showed that 
great internal pressures were developed in cans of corn when the 
corn was canned without precooking, and that the vacuum was cor- 
respondingly lower. During cooking, corn swells considerably, and 
unless heat is applied in some form before the corn is canned difficul- 
ties may be encountered. In tin, the cans may buckle; and when 
glass jars are used, breakage from internal pressure is often con- 
siderable. 
This swelling is due partly to gelatinizing of the starch, but 
mostly to the expansion of air held in the tissues or otherwise incor- 
porated in the material. 
Scalding on the cob in boiling water has the disadvantage that 
more loss of sugar and other nutrients takes place, though this is 
not very great unless the scalding is greatly prolonged. Commer- 
cially, scalding on the cob would be impracticable, or at least ex- 
pensive. The experiments of the writers have indicated that the 
best results are obtained when the corn, with the proper proportion 
of liquor, is precooked to at least 80° C., just prior to filling the cans 
and processing. 
CHEMICAL CHANGES DURING THE PRECOOKING OF CORN. 
Table 4 shows the results of chemical analyses of Country Gentle- 
man sweet corn, before and after precooking to 80° C. The changes 
in composition are very slight. The slightly higher moisture con- 
tent of the precooked sample is due to an error in sampling, as ac- 
tually under the conditions of the precooking a slight evaporation 
took place. There seems to be a slight loss in sugar, but this is not 
enough to be of very great significance. 
Table 4. — Results of analyses of Country Gentleman siveet corn, oefore and 
after precooking. 
[Each result is the average of three samples.] 
Average constituents (per cent) . 
Treatment of material. 
Mois- 
ture. 
Solids. 
Alcohol. 
Sugars. 
Poly- 
Solu- 
ble. 
Insol- 
uble. 
Reduc- 
ing. 
Nonre- 
ducing. 
Total. 
saccha- 
rides. 
69.09 
69.57 
30.91 
30.43 
7.88 
7.40 
23.03 
23.03 
1.05 
1.01 
3.49 
3.03 
4.54 
4.04 
19.63 
After precooking to 80° C 
19.89 
CONCLUSIONS REGARDING THE PRECOOKING OF SWEET CORN. 
These studies indicate that scalding on the cob, or precooking the 
cut corn, is not necessary for preservation of desirable color and 
flavor, but is a very advantageous means of securing a proper vacuum. 
