RELATION OF BENZOIC ACID CONTENT AND OTHER
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RELATION OF BENZOIC ACID CONTENT AND OTHER
CONSTITUENTS OF CRANBERRIES TO
KEEPING QUALIITY1
J. A. CLAGUE AND C. R. FELLERS
Introduction
The benzoic acid naturally occurring in cranberries has long been
regarded as the preserving agent responsible for the good keeping qualities
of the berries and the products manufactured from them (10, 15). The
purpose of this investigation was to determine the benzoic acid content
of several Massachusetts, New Jersey, and Wisconsin varieties, and to note
the amount present in relation to other constituents and to the keeping
qualities of the berries.
LOEW (8) was probably the first to report the presence of benzoic acid
in the German Preisselbeere (Vaccinium vitis idaea). Subsequent quanti-
tative determinations were reported by other workers (5, 7, 9). GRBEL
(4) thoroughly studied the free and combined benzoic acid of the Preissel-
beere, the Moosbeere (V. oxycoccus), and the American cranberry
(V. macrocarpum). He found the Preisselbeere to contain as much as
0.22 per cent. total benzoic acid, the Moosbeere and the cranberry having
a content of 0.02-0.06 per cent. MASON (10) found the American cran-
berry to contain 0.05 per cent. benzoic acid; RADIN (16) reports 0.06 per
cent. as the content; BLATHERWICK and LONG (2) give the percentage as
0.096; and NELSON (14) reports 0.069 per cent. The varieties analyzed
were not stated in the papers. Chemical composition of the important
American varieties of cranberries has been studied by MORSE (12).
Experimental methods
The cranberries were shipped to the laboratory in quarter-barrel boxes
and were put into cold storage (20 C.) upon receipt, samples being taken
out as needed for analysis.
The procedure followed in the determination of benzoic acid was for
the most part that recommended by the A. 0. A. C. (1). A modification
was made in the treatment of the chloroform extract. The residue from
the latter was dissolved in ether and transferred to test tubes and treated
in the manner described by MONIER-WILLIAMS (11). The ether was
evaporated under a stream of air dried by buibbling through concentrated
sulphuric acid. The residue was washed down from the sides of the tubes
until it was contained in the bottom 2 or 3 cc. Some previously ignited
sand was added and a mark filed on the test tubes about 4 cm. from the
1 Contribution No. 195 of the Massachusetts Agricultural Experiment Station.
631
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Copyright © 1934 American Society of Plant Biologists. All rights reserved.632 PLANT PHYSIOLOGY
bottom. A disk of filter paper was pushed down to the mark. A 1-gallon
slip cover can was used as a suiblimator. The test tubes were pushed
through holes in an asbestos mat which fitted over the can, the test tube
base resting on a wire basket inside the can, so that the filed mark was
just below the surface of the asgbestos mat. Cork stoppers were placed
loosely over the mouth of the test tubes and they were heated at 160°-
1700 C. for about two hours. After cooling, the bottom 4 cm. of the tubes
were cut off at the mark. The crystals of benzoic acid were all sublimated
in the upper part of the tube. Any that had fallen down were caught on
the filter paper disc, which was removed and from which the crystals were
shaken back into the upper part of the test tube. The test tubes with the
suiblimate were dried in a desiccator over sulphuric acid and then weighed.
The benzoic acid was washed into a small Erlenmeyer flask with alcohol,
and the test tubes again weighed. The difference in weight represents the
benzoic acid present in the sample. The sublimate washed out of the test
tube was titrated with 0.05 N sodium hydroxide, thus giving a check on
the gravimetric determination. This modified method gave very reliable
results and reduced the time required to make a determination.
Total acids and pectin, as alcohol precipitate, were determined by the
A. 0. A. C. (1) methods.
The soluble solids content of the juice from new crushed cranberries
was determined with the Abbe refractometer. Results are not so accurate
as those obtained by gravimetric methods, but give good comparative data.
The number of berries per quart container was considered to be the
most convenient measure for their size. The weight of a quart of berries
represents the average weight of ten quarts.
Results
The benzoic acid content of 24 varieties is shown in table I. Results
for two years are given for four varieties. The percentage of the berries
spoiled at the time of analysis is shown. The rating of varietal keeping
qualities as given by C. S. BECKWITH of the New Jersey Cranberry Sta-
tion, H. J. FRANKLIN of the Massachusetts Station, and C. M. CHANEY of
the American Cranberry Exchange is also shown.
With one exception (Berry Berry variety) th,e percentage of benzoic
acid was over 0.05, the maaximum being 0.098.
According to CRUESs and IRISH (3), fruit products with a pH of 3 to
3.5 require less than 0.05 per cent. sodium benzoate (equivalent to about
0.04 per cent. benzoic acid) for preservation. In grape products, where the
pH was 2.6 and 3.0, the equivalent of 0.02 per cent. benzoic acid sufficed
to preserve the fruit against yeast spoilage.
The pH of sound cranberries is 2.35-2.6 (17); hence preservative con-
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Copyright © 1934 American Society of Plant Biologists. All rights reserved.CLAGUE AND FELLERS: KEEPING QUALITY OF CRANBERRIES 633
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Copyright © 1934 American Society of Plant Biologists. All rights reserved.634 PLANT PHYSIOLOGY
ditions in cranberries are apparently ideal. However, annual loss from
fruit rot does constitute as much as 25 per cent. of the total cranberry crop
of the United States (18).
There seems to be no definite relationship between the keeping quality
of cranberries and their benzoic acid content. Factors other than the latter
must be considered. The infection by spoilage microorganisms usually
occurs relatively early in the growing season (19). The benzoic acid is
present only in traces in the immature berries and the amount increases
gradually to a maximum as the berry ripens (4, 10). Benzoic acid exerts
a preservative rather than a germicidal action on microorganisms, in the
concentrations in which it is present in the ripe cranberry. If the infective
agent has already established itself, therefore, the gradually increasing
quantities of the acid apparently are not sufficient to destroy the fungi.
Furthermore, GRIEBEL (4) has pointed out that some of the benzoic acid
in cranberries is combined as esters and as a glucoside of vacciniin. As
much as 35 per cent. of the total benzoic acd was in the form of the gluco-
side in some American cranberries analyzed by GRIEBEL. It is not known
whether this combined form of benzoic acid exerts any antiseptic action.
The percentage of total acids (calculated as citric) in the cranberries
analyzed varied from 2.08-2.80, with an average of 2.35. Of the nine varie-
ties listed as only fair or as poor keepers, six had total acid contents below
the average and one was only 0.03 per cent. above. The keeping qualities
of 15 varieties were rated from good to excellent. Nine of these had total
acid contents above and six below the average.
Pectin as alcohol precipitate was found to vary between 0.86 and 1.66
per cent., averaging 1.16 per cent. No definite relationship existed between
keeping quality and pectin content. The average soluble solids content was
9.1 per cent., with a maximum of 10.6 and a minimum of 7.2.
Some of the best keeping varieties had a high soluble solids content, the
variety Budd's Blues having the maximum amount and having a rating as
excellent. On the other h-and, some of the berries which were poor keepers
also had a high percentage of soluble solids.
EFFECT OF QUINIC ACID AS A PRESERVING AGENT
Cranberries are known to have a quinic acid content of as much as 1
per cent. (6,13). The following test was made to determine the efficiency
of quinic acid as an antiseptic, and also to note the effect of the combina-
tion of quinic and benzoic acids.
To one series of tubes containing sterile sweet cider there was added
2 per cent. quinic acid plus 0.1, 0.05, and 0.025 per cent., and no sodium
benzoate. A similar series was made with the addition of 1 per cent. quinic
acid and a third contained the sodium benzoate alone. The media were
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Copyright © 1934 American Society of Plant Biologists. All rights reserved.CLAGUE AND FELLERS: KEEPING QUALITY OF CRANBERRIES 635
inoculated with yeasts and molds and incubated at room temperature. Re-
sults are shown on table IL
TABLE II
PRESERVATIVE EFFECT OF QUINIC AND BENZOIC ACIDS
Quinic acid per cent. 2 2 2 2 1 1 1 1 0 0 0
Benzoic acid per cent. 0.1 0.05 0.025 0 0.1 0.05 0.025 0 0.1 0.05 0.025
Yeasts ......................................
- _- + - - - + - +
Molds ........................................ - +
After three days' incubation there was abundant growth in all tubes
containing the quinic acid alone, and no growth in the others. At the end
of ten days the only change was that yeast was growing in the tube con-
taining 0.025 per cent. sodium benzoate alone. The increased acidity of
the media containing the added quinic acid probably accounted for this
difference. No further changes were noted after a month 's incubation
period. It was concluded that the naturally occurring quinic acid did not
exert an appreciable antiseptic or germicidal action on fruit spoilage
organisms.
Summary and conclusion
1. The benzoic acid content of twenty-four varieties of cranberries
ranged from 0.029 to 0.098 per cent., with an average of 0.065 per cent.
2. The varieties with the best keeping qualities did not always have a
high benzoic acid content, so that apparently factors other than benzoic
acid content alone must be largely responsible for the keeping properties
of the berries.
3. The quinic acid present did not exert any appreciable preservative
action on spoilage organisms.
4. The large percentage of varieties having poor keeping qualities had
low total acid content, while the good keeping varieties in the majority of
cases had a high total acid value.
5. Pectin and soluble solids content did not correlate with keeping
quality.
6. Benzoic acid is present in the ripe berry in amounts sufficient to give
a preservative action. However, high benzoic acid content in a variety is
not always indicative of good keeping quality; apparently certain physical
or environmental factors are of greater importance.
MASSACHUSETTS STATE COLLEGE
AMHERST, MASSACHUSETTS
LITERATURE CITED
1. ASSOCIATION OF OFFICIAL AGRICULTURAL CHEMISTS. Official and tenta-
tive methods of analysis. 2d ed. 1925.
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Copyright © 1934 American Society of Plant Biologists. All rights reserved.636 PLANT PHYSIOLOGY
2. BLATHERWICK, N. R., and LONG, M. L. The increased acidity pro-
duced by eating prunes and cranberries. Jour. Biol. Chem. 57:
815-818. 1923.
3. CRUESS, W. V., and IRISH, J. H. Role of acidity in the preservation
of fruit specialties. Fruit Products Jour. and Amer. Vinegar
Ind. p. 177. Feb. 1931.
4. GRIEBEL, C. Beitriige zur Kenntnis der chemischen Zusammensetzung
der Preisselbeeren, Moosbeeren und Kranbeeren. Zeitschr. Unter-
such. Nahr. und Genussmtl. 19: 241-252. 1910.
5. KANGER, Zur Frage iiber die chemische Zusammensetzung und die
pharmakologische Wirkung der Preisselbeeren. Arch. experim.
Pathol. u. Pharmakol. 50: 46-75. 1903.
6. KOHMAN, E. F., and SANBORN, N. H. Isolation of quinic acid from
fruits. Ind. & Eng. Chem. 23: 126. 1931.
7. LEHMANN, K. B. Die Benzoesiiure. Chem. Zeitung. 32: 949. 1908.
8. LOEW, 0. tber die Quelle der Hippursiiure im Harn der Pflanzen-
fresser. Jour. Prakt. Chem. 19: 309-312. 1879.
9. MACH, E., and PORTELE, K. Pber die schwere Vergarbarkeit und die
Zusammensetzung des Preisselbeersaftes. Landw. Vers.-Sta. 38:
69-78. 1890.
10. MASON, G. C. The occurrence of benzoic acid naturally in cranberries.
Jour. Amer. Chem. Soc. 27: 613-614. 1905.
11. MONIER-WILLIAMs, G. W. Determination of benzoic acid in foodstuffs.
Analyst 52: 229. 1927.
12. MORSE, F. W. A chemical study of cranberries. Massachusetts Agr.
Exp. Sta. Bull. 265. 1930.
13. . Annual report, Massachusetts Agr. Exp. Sta. Bull.
280. 1932.
14. NELSON, E. K. Non-volatile acids of the pear, quince, apple, logan-
berry, blueberry, cranberry, lemon and pomegranate. Jour.
Amer. Chem. Soc. 49: 1300-1302. 1927.
15. NESTLER, A. Ein Schutzmittel der Preisselbeere. Die Umschau. 13:
1016-1018. 1909.
16. RADIN, M. J. A note on the quantity of benzoic acid contained
in prunes and cranberries. Ind. & Eng. Chem. 6: 518. 1914.
17. RICE, C. C. Preservation, utilization and properties of cranberry
juice. Master's thesis. Massachusetts State College. 1932.
18. SHEAR, C. L. Cranberry diseases and their control. U. S. Dept. Agr.
Farmers Bull. 1081. 1920.
19. STEVENS, N. E. Notes on cranberry fungi in Massachusetts. Phyto-
path. 14: 101-107. 1924.
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