Canning Certain Vegetables with Hydrochloric Acid

R. C. BURRELL, ESTHER M. JOHNSON, BEVERLEE J. RICE, and PHYLLIS J. SOHN

The Ohio State University, Columbus, Ohio

C ANNING the surplus products of war gardens has presented a problem due to the lack of pressure

cookers, since the majority of the common vegetables, with the exception of tomatoes, have too high a pH to obviate the danger of bacterial spoilage, even botulism, unless pressure sterilization is employed.

According to Shrader (4) Colostridium botulinum grows best a t a neutral or 'slightly alkaline reaction, although slight growth may occur at pH values of 5.0 or slightly less. The State Board of Health of California has established pH 4.5 as the dividing line between acid and nonacid foods (1, a). A relatively high acidity in the canned product also contributes to the conservation of both vitamin C (1, b) and carotene (3).

I t was therefore deemed of interest to investigate the possibilities of the use of acid in the canning of vege- tables with respect to:

approximately 1 gram) was found to be the right quan- tity to remove the sour taste and yet not quite neutral- ize the product (which, if done, would cause a more rapid destruction of vitamin C during the heating pre- liminary to serving). The beans, after neutralization by the baking soda, had a pH of 6.2; the vegetable mixture, 4.9 to 5.0.

The exact canning procedures were as follows: The snap beans cut in one-inch lengths and blanched, or the vegetable mixture, either blanched or not, were packed loosely in pint Mason jars. One-half teaspoon of salt was added to each jar, then 25 cc. of 0.5 N hydrochloric acid, and finally sufficient water to bring the level of liquid up to the base of the rim. The jars were closed with No. 10 glass-top"'Presto" closures (unscrewing the band one-fourth turn before processing) and placed in a water bath. They were allowed to process for 45

1. Finding an acid that would not give an undesirable flavor minutes of active to the canned product; To prepare for serving, the Contents of the jar were

2. Findine a suitable concentration to use under actual can- em~tied into a sauceDan and water added as desired. - ning conditions; One-fourth teaspoon of baking soda was added to each

3. Determining what the effects of the acid are on the quality Sample and heating was continued for or minutes, of the product when subsequently used as food.

The addition of the contents of one small envelope of

EXPERIMENTAL PROCEDURE "G. Washington's Instant B r o t h powder makes a verv valatahle vegetable sou^ from the vegetable . . - -

Two vegetable products were investigated, green mixture. snap beans and a mixture of vegetables suitable for In a series of experiments, determinations of the vegetable soup. For the latter, the following propor- vitamin C content (2 ) of the original vegetable mixture, tions by volume were used: 2 parts shredded cabbage; the stored product, and the product prepared for sen- 1 part tomatoes; 1 part sweet corn; 1 part chopped ing were made. Due to the lack of homogeneity of the celery; ' '2 part diced carrots; '/z part chopped onions; product the results obtained from separate samples and ' / ' I part chopped parsley. With the beans, blanch- were variable. However, they confirmed the already ing was carried out with boiling water for three min- established idea that acidity is favorable to the preserva- Utes. For most of the experiments, the vegetable mix- tion of the vitamin C content of a foodstuff. ture was prepared unblanched. Fifty cans of the vegetable mixture and forty cans of

Hydrochloric was selected as the acid, since in the sub- snap beans were stored for periods of six months to one sequent preparation of the canned product for the table year without any spoilage occurring. the addition of a little baking soda not only removed the sour taste but merely produced a little more ordi- LITERATURE CITED

nary salt asthe result of such neutralization. After trials (1) (a) Cnusss, W. V., "Commercial Fruit and Vegetable Prod- of various concentrations it was found that 25 cc. of ucts," 2nd Ed.. McGraw-Hill Book Co. , Inc., New York,

1938, p. 121. (b ) Ibid., p. 720. 0.5 IV hydrochloric acid added to a one-pint can would (2) DUNNIGAN, M., M. LEWIS, AND M. R. S~ETLAR, *'A study OF

give a pH of 3.6 with the snap beans and a pH of 3.5 to the ascorbic acid control of the diet commonly prescribed

3.7 with the vegetable mixture. Such pH values are for patients with gastric ulcers," Ohio J. Sci., 44, 123 (1941).

unfavorable to the activity of most enzymes as well as (3) SHETLAR, C. L., AND M. R. SHETLAR. Unpublished data. to the growth of bacteria. When preparing the product Dept. of Agricultural Chemistry, The Ohio State Uni-

versity (1944). use, One-quarter of a baking (4) SKRADE~, J. H., "Food Control: Its Public-Health Aspects," from a kitchen measuring spoon (weight of NaHC03 John Wiley and Sons, Inc, New York, 1939.

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