ASCORBIC ACID IN TOMATOES 29 



STUDY OF ASCORBIC ACID IN CANNED TOMATO JUICE 

 Effect of Canning 



Marglobe tomatoes were quartered, heated in a steam-jacketed kettle to soften, 

 and then forced through a fine iron screen to remove the pulp. The description 

 of the canning process and sampHng for ascorbic acid is given in Table 12. 



The loss of ascorbic acid during the heating and pulping processes was in- 

 significant. The greatest destruction occurred during the concentration of the 

 pulped juice. Concentration of home-manufactured juice is advisable as it 

 removes some of the excess water thereby preventing separation of finely divided 

 particles. Commercially canned tomato juice is homogenized to obtain a uniform 

 suspension and therefore concentration is unnecessary. No noticeable destruc- 

 tion of ascorbic acid occurred when glass and tin containers were filled with juice, 

 sterilized, and cooled. This table shows the general trend of ascorbic acid destruc- 

 tion during the manufacture of tomato juice. 



Effect of Storage of Canned Juice 



Ascorbic Acid Studies 



The data in Table 12 show that there was no apparent loss in ascorbic acid 

 during a 30-day storage period. No appreciable loss during a storage period of 

 121 days is also shown by the data in Table 2. 



Daniel and Rutherford (1936) stored tomato juice in glass jars and jars wrapped 

 in black photographic paper for six months (209 days). The juice stored in 

 wrapped jars lost 34 percent of its ascorbic acid and the unwrapped jars 24 per- 

 cent. As this evidence was not in agreement with other storage data, it seemed 

 advisable to conduct an experiment for a period of over 121 days. 



Tomato juice containing 67 international units of ascorbic acid per ounce was 

 stored in plain and amber glass containers under dark and normal light condi- 

 tions. Table 13 shows that there was a small continuous loss of ascorbic acid 

 in plain glass containers whether stored in the dark or in light. Amber glass 

 inhibited losses up to a period of at least 80 days. Storage conditions of light and 

 dark at room temperature (21° C.) did not affect the losses of ascorbic acid in 

 tomato juice. The losses that occurred over a storage period of 400 days did not 

 exceed 25 percent, i. e., from 67 international units per ounce to 50 units. The 



Table 13. — Effect of Storage on the Ascorbic Acid Content of Canned 



Tomato Juice 



Percentage Loss in Ascorbic Acid 

 after Storage for — 



Container and Storage Conditions 



Flint glass at room temperature 



Light 



Dark 



Amber glass at room temperature 



Light 



Dark. 



Tin can at room temperature. . . . 



