SCALDING, PRECOOKING, AND CHILLING 3 
Careful perusal of this literature 3 affecting these widely recom- 
mended practices shows in many instances lack of knowledge as to 
what actually does happen when the recommendations are followed, 
and much confusion has resulted among those who were desirous of 
knowing what methods to pursue. Furthermore, carefully con- 
trolled investigations by scientists of recognized standing, partic- 
ularly along the line of the losses in nutrients resulting from scald- 
ing and cooking in water, and also with respect to the recommended 
methods as related to the necessary sterilization of canned food, have 
raised doubts in the minds of many as to the advisability of the 
unrestricted scalding and chilling operations in the canning of foods. 
The wise utilization of our food resources is of fundamental im- 
portance. The economical production of our canned foods, the 
conservation of their nutritive properties, and the maintenance of 
high quality, and assurance of healthfulness, are matters of vita] 
importance. The operations involved in their manufacture, there- 
fore, should be subjected to critical study, and the principles in- 
volved should be thoroughly understood. 
This bulletin sets forth the results of studies carried on during the 
four years ended in the winter of 1921-22, which were undertaken 
for the purpose of throwing light upon some of these matters, and 
they are presented here with the hope that they may help in clear- 
ing away confusion and assist in the improvement and standardiza- 
tion of canning methods. 
APPARATUS AND METHODS USED. 
The scalding vessel employed in these studies consisted of an 
enamel-lined 10-gallon tank fitted with a block-tin steam coil. Its 
volume was therefore sufficiently great to allow the introduction of 
suitably large quantities of the test material without checking the 
vigorous boiling for more than a few seconds. For some of the work, 
a wire basket, specially constructed to fit the dimensions of the tank, 
was used, and in part of the work cheesecloth was substituted for 
this basket. 
A steam chamber suitably fitted with wire trays was used for the 
studies on steam treatment, and enamel-ware buckets were used for 
the cold-water treatment of the scalded materials. 
The source of heat was the 60-horsepower steam boiler used for 
general purposes, which furnished abundant steam under pressure 
for all needs. No tests using small kettles or steamers on the stove 
or open flame were made. 
In those experiments involving the canning of the test material, 
both the standard packers' tin cans and the glass jars in common 
household use were employed. Processing, when practiced, was done 
in a water bath of large capacity heated by a steam coil or in an 
autoclave, as the case required. 
The usual chemical laboratory equipment was used for the 
analytical work. 
In all cases during the experiments, time was counted from the 
instant the material was plunged into the boiling water; or, where 
3 For the benefit of those who desire to look further into the literature of the subjects 
under discussion, a list of pertinent nontechnical publications is appended to this bulletin. 
