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Contribution from the Bureau of Chemistry, Carl L. Alsberg, Chief 
May 29, 1915. 
(PROFESSIONAL PAPER., 
;. METHODS FOLLOWED IN THE COMMERCIAL 
; CANNING OF FOODS.’ 
By A. W. Birrine. 
; CONTENTS. 
4 . Page. Page. 
_ Modern factory equipment and methods..... 1 | Extent of the canning industry in the United 
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mse ot the term ‘“‘canned”’.-:.....--...--.-.- 13. Woe xperimentall work: 2. eset 20 ek. eee eee 19 
as Bin eee baie a A ee 13 | Detailed consideration of the various prod- 
\ Effect of heat and cold.............-...----- 14 TICES fo: Os ER Eo ah is i ee ea 21 
Cost of canned foods compared with fresh - -. 15 
MODERN FACTORY EQUIPMENT AND METHODS. 
METHODS OF STERILIZATION. 
Sterilization may be accomplished by heat below, at, or above the boiling tem- 
perature, depending upon the length of time the heat is applied and the number of 
applications made. It is not practicable to sterilize all foods in the same way because 
of injury to quality or prohibitive expense. Sterilizing below the boiling point is 
feasible only for a few products, principally fruits, and then is advisable only when 
it is desired to preserve a very fine appearance. This may be accomplished above 
165° F. by maintaining the temperature for a longer time than when boiling, or by 
repeating the operation on two or more successive days. The object is to prevent 
breaking the tissue and loss of juices from the fruits by excessive heat. This method 
of sterilization has been applied experimentally and in private canning with grati- 
fying results, but it involves so much time and labor that it is not used commercially 
except in a limited way. Sufficient work has not been done to say definitely what 
products can best be treated in this way nor what temperatures are best suited for 
different foods. It has been used chiefly with foods in glass, though equally satis- 
factory results are obtained with foods in tin. 
Cooking at boiling temperature is practiced with nearly all fruits, as the germs 
present are easily destroyed. Most of the fruits are processed for from 12 to 25 minutes. 
1A revision of Bureau of Chemistry Bulletin 151, enlarging upon certain phases of the manufacturing 
processes, and incorporating a summary of the results of the experimental work of the season of 1912 and 
1913. Since the information includes only the methods of commercial canning, it is of no interest to the 
home canner. Presentation of the trade practices does not imply an indorsement by the Bureau of 
Chemistry. Prepared by A. W. Bitting while food technologist of the bureau, 
79258°—Bull. 196—15——1 
