ANNUAL REPORT, 1943-44 47 



(the test period has not been completed yet). The redox potentials of hot-break 

 tomato juice packaged in plain tin cans, in commercial glass jars with metal lids, 

 and in commercial all-glass jars and stored at 70°F. are being investigated. As 

 with the citrate-buffer ascorbic-acid packs the tomato juice packed in plain tin 

 cans showed a lower potential, but the difference in potential between the tin 

 container and the two glass containers was much less than with the citrate-buffer 

 ascorbic-acid packs. Differences in ascorbic acid content were almost insignifi- 

 ficant. Flavor changes could not be correlated with redox potential. 



A survey of spoilage encountered by home canners in Massachusetts in 1942 

 indicated that 293 families who canned a total of 73,393 jars encountered approx- 

 imately 2 percent spoilage. The amount of spoilage is not considered excessive 

 in view of the many variables encountered in home canning at the present time. 

 In the laboratory examination of home canned foods, bacteriological culture 

 tests were found to be the most reliable criterion of spoilage. As represented by 

 this investigation it would appear that about three-fourths of home-canning 

 spoilage is due to understerilization and one-fourth to improper sealing. The boil- 

 ing water bath method of processing is not adequate to destroy certain types of 

 bacteria encountered in the home canning of low acid vegetables. While a 

 pressure canner correctly used is satisfactory for processing, understerilization 

 may result if it is mis-used. From experimental evidence it would appear that 

 home-canning process times at 240°F. (10 pounds pressure) as recommended at 

 present may be more severe than are necessary and that in many cases they might 

 be reduced. However, before any general recommendations are made, more 

 experimental work must be done and careful consideration given to the man\- 

 variables involved. 



Experimental data indicate that many of the directions provided for home 

 canning in pressure canners do not allow for sufficient venting and in some 

 instances might contribute to underprocessing. A venting time of at least 10 

 minutes is to be recommended for pressure canners of the size commonly used 

 for home canning. 



A compreliensive study has been made of different types of glass containers 

 and jar seals available for home canning under war-time conditions, and direc- 

 tions for their use were made available. Although some difficulties have been 

 reported in the use of jars and seals, it is evident that much of the trouble was 

 caused by the improper use of satisfactory equipment. Jar rings and seals made 

 of synthetic and reclaimed rubber have given very good results from the stand- 

 point of making an original seal and also of maintaining it during the storage 

 life of the canned product. 



Comparison of Canning, Freezing, Dehydrating, and Salting as Methods of 

 Home Food Preservation. (W. B. Esselen, Jr., C. Dubord, and F. P. Griffiths.) 

 Four varieties of snap beans, two varieties of cabbage and carrots, and one 

 variety of sweet corn at two different stages of maturity were preserved by four 

 home methods: canning, freezing, dehydrating, and salting. The preserved pro- 

 ducts were stored for six months and changes in their ascorbic acid content 

 palatability, flavor, texture, and color were observed and compared. Freezing 

 appeared to yield the most acceptable product, followed by canning and dehydra- 

 tion. The salted products, with the exception of sauerkraut, were unsatisfactor\'. 



On a basis of the final cooked ready-to-serve product, the total losses of ascorbic 

 acid (referred to the fresh product) amounted to 85-95 percent in both the canned 

 and frozen vegetables. The deh^'drated vegetables maintained their quality to 

 a high degree during three months' storage at room temperature (75°-80°F.) 

 but after six months a definite deterioration in flavor was observed. 



