20 MASS. EXPERIMENT STATION BULLETIN 341 



CONCLUSION 



As a result of a two-year investigation of the vacuums and internal pressures 

 of all-glass canning jars during heat processing and of practical cooperative 

 experience involving over 16,500 all-glass jars, 50 canned foods, and 60 home 

 canners, it is considered advisable to fully recommend sealing the jar by 

 tightening the wire bail previous to thermal treatment (processing). 



This method decreases markedly the losses of liquid from jars during process- 

 ing, improves the appearance of the contents, saves time, obviates the necessity 

 of handling the hot jars after processing, and has no effect on either breakage 

 or spoilage. 



REFERENCES 



1. Clark, E. D., Clough, R. W., and Shostrom, O. E. 1923. Function of 



vacuum in canned salmon. Reprinted from the Pacific Fisherman. May, 

 June, and July, 1923. 



2. Ford, K. L. 1927. Vacuum — its measurements and its functions in the 



packing industry. Glass Container No. 6: 5-6 and 24. 



3. Ford, K. L. 1930. General principles of retort operation. Glass Con- 



tainer No. 6: 5-7 and 36. 



4. Ford, K. L., and Osborne, A. G. 1928. Heat transfer determinants. 



Glass Container No. 1: 7-8 and 34. 



5. Levine, A. S. 1936. Some factors involved in the thermal treatment of 



all-glass containers. Master's thesis, Massachusetts State College. 55 p. 



6. Maclinn, W. A. 1935. Some internal physical conditions in glass containers 



of food during thermal treatment. Master's thesis, Massachusetts State 

 College. 30 p. 



7. Maclinn, W. A., and Fellers, C. R. 1936. Vacuum determinations in all- 



glass canning jars. Food Research 1: 41-44. 



8. Magoon, C. A., and Culpepper, C. W. 1921. A study of the factors 



affecting temperature changes in the container during the canning of 

 fruits and vegetables. U. S. Dept. Agr. Bui. 956, 55 p. 



9. Magoon, C. A., and Culpepper, C. W. 1922. Relation of initial temper- 



ature to pressure, vacuum, and temperature changes in the container 

 during canning operations. U. S. Dept. Agr. Bui. 1022, 52 p. 



Publication of this Document Approved by Commission on Administration and Finance 

 3m— 4 '37 No. 468 



