434 
Joumal of Agricultural Research, 
Vol. XXVIII, No. 5 
WHEN IS CORN AT THE BEST CANNING STAGE? 
To determine at what stage of maturity corns were in best condition for canning 
studies were made along several lines. The condition of the corn as indicated by 
physical development received careful attention in order to discover at what 
stage the highest yields in cut corn would be obtained and at what stage it would 
seem most advantageous to harvest the crop; chemical analysis of the cut corn 
was made at all stages of development that it might be learned at what period the 
amount and the constitution of the carbohydrates would indicate highest quality; 
and finally sample packs of the different varieties at various stages were prepared 
so that a test of the comparative table qualities of the canned products might be 
made. The close correlation of the findings from these three lines of study is of 
considerable interest. 
From the standpoint of safe practice it would seem that the most favorable 
time to harvest corn for canning purposes would be at or very shortly after the 
time when the rate of development of the kernels had reached its peak, as beyond 
this time the rate of increase falls off rapidly and the hazards of successful packing 
are increasingly great. Careful study of the figures giving the percentage of cut 
corn from the husked ears at the different stages (see Table I) obtained in these 
studies, shows that in the great majority of cases the peak of the rate of develop¬ 
ment occurred in this instance at between 15- and 20-day stages, in no case occur¬ 
ring beyond the 25-day stage. This result is in close agreement with those 
supplied by the chemical analyses. 
It is common knowledge that high quality in canned sweet corn is closely 
associated with high natural sugar content, and that added sugar does not give 
the same pleasing result as the sweetness supplied by nature. It is apparent 
therefore, that corn should be canned while the sugar content is high, and if 
possible, at the time when it is present in greatest amount. The chemical 
analyses made of the different varieties of sweet corn at age intervals of 5 days, 
in the present studies, showed that the highest pojmt in the development of sugar 
under the present conditions was reached at the 15-day stage. This was found 
true for all varieties regardless of the time of planting or the earliness or lateness 
of the corn. It seems, therefore, that from the standpoint of natural sweetness 
canning should not be delayed for any considerable period beyond the 15-day 
stage. 
These two lines of evidence are supported by a third, namely, the canning tests 
which have just been discussed. These all combine to point to a rather definite, 
brief period represented by the 20-day stage, or a few days earlier for rapid¬ 
maturing strains, during which it is possible to attain the highest quality in the 
canning of corn. Beyond this point the increase in yields are small, the products 
are lacking in natural sweetness, the desirable flavor is impaired and the kernels 
become increasingly tough. 
9 
THE RELATION OF SUGAR CONTENT TO SWEETNESS 
In the consideration of the relation of the sugar content as indicated by chemical 
analysis, and the sweetness as indicated by taste, it needs to be pointed out that 
the total sugar content of a particular substance is not an exact measure of its real 
sweetness. Two factors are operative here, namely, the kind of sugar present 
and its concentration. Since cane sugar has higher sweetening power than dex¬ 
trose, or invert sugar, changes in the relative proportions of these affect the 
sweetness even when the figures for total sugars present are the same. Since, also, 
the moisture content is constantly changing in the corn the percentage of sugar as 
shown by the analyses is not a real measure of the concentration. The per cent 
of sugar at the 15-day stage was found to be considerably higher than at 20 days, 
