The Formation of Carbonyl Compounds in Cucumbers

Authors

  • H. P. FLEMING,

    1. U. S. Food Fermentation Laboratory, Southern Utilization Research and Development Division Agricultural Research Service, U. S. Department of Agriculture; and Department of Food Science, North Carolina State University Raleigh, North Carolina 27607
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  • W. Y. COBB,

    1. U. S. Food Fermentation Laboratory, Southern Utilization Research and Development Division Agricultural Research Service, U. S. Department of Agriculture; and Department of Food Science, North Carolina State University Raleigh, North Carolina 27607
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  • J. L. ETCHELLS,

    1. U. S. Food Fermentation Laboratory, Southern Utilization Research and Development Division Agricultural Research Service, U. S. Department of Agriculture; and Department of Food Science, North Carolina State University Raleigh, North Carolina 27607
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  • T. A. BELL

    1. U. S. Food Fermentation Laboratory, Southern Utilization Research and Development Division Agricultural Research Service, U. S. Department of Agriculture; and Department of Food Science, North Carolina State University Raleigh, North Carolina 27607
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  • Paper number 2515 of the Journal Series of the North Carolina State University Agricultural Experiment Station, Raleigh, North Carolina.

  • The authors wish to thank P. J. Hauser and R. M. Swindell for their valuable technical assistance in this study. Gratitude is expressed to the Mount Olive Pickle Company, Mount Olive, N. C., and Perfect Packed Products, Inc., Henderson, N. C., for supplying cucumbers throughout this study.

  • Mention of firms or products does not imply endorsement.

SUMMARY

The carbonyl contents of benzene extracts of aqueous cucumber homogenates were estimated spectrophotometrically as the 2, 4-dinitrophenylhydrazones. A large increase in the formation of carbonyl compounds occurred when cucumbers were blended with water in the presence of oxygen. This formation of carbonyl compounds was prevented by three methods: blending the cucumbers at pH 1.0; blending in an oxygen-free atmosphere; and heating whole cucumbers to an internal temperature of 77°C before blending.

Chromatographic assays indicated that negligible amounts of the 2-enals, 2, 6-nonadienal, 2-nonenal, and P-hexenal are present in intact cucumbers; but a rapid synthesis of this class of carbonyl compounds occurred when fresh cucumbers were blended in the presence of oxygen. The most significant increase occurred in the formation of 2, 6-nonadienal, the aldehyde largely responsible for the flavor of fresh cucumbers. There were indications that ethanal and propanal were present in appreciable levels in intact cucumbers.

These observations suggest that the characteristic flavor components of fresh cucumbers are generated enzymatically as a consequence of cutting or mechanically rupturing the fruit.

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