|Perez Diaz, Ilenys|
Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/4/2010
Publication Date: 5/1/2010
Citation: Perez Diaz, I.M., Mcfeeters, R.F. 2010. Preservation of acidified cucumbers with a natural preservative combination of fumaric acid and allyl isothiocyanate that target lactic acid bacteria and yeasts. Journal of Food Science. 75(4):M204-M208.
Interpretive Summary: This paper provides guidelines for microbiological preservation of cucumbers without fermentation or application of a thermal process. Preservation is achieved by holding cucumbers in a solution containing acetic acid, fumaric acid to prevent growth of lactic acid bacteria, allyl isothiocyanate to inhibit yeasts, and calcium chloride to maintain the firmness of the cucumbers. The stored cucumbers may then be further processed into edible pickle products. Preservation of cucumbers in bulk allows them to be shipped and be stored until there is demand for the product. The approach to preservation demonstrated here would reduce the generation of waste and the time and labor required to convert the stored cucumbers into consumer products.
Technical Abstract: Without the addition of preservative compounds cucumbers acidified with 150 mM acetic acid with pH adjusted to 3.5 typically undergo fermentation by lactic acid bacteria. Fumaric acid (20 mM) inhibited growth of Lactobacillus plantarum and the lactic acid bacteria present on fresh cucumbers, but spoilage then occurred due to growth of fermentative yeasts, which produced ethanol in the cucumbers. Allyl isothiocyanate (2 mM) prevented growth of Zygosaccharomyces globiformis, which has been responsible for commercial pickle spoilage, as well as the yeasts that were present on fresh cucumbers. However, ally isothiocyanate did not prevent growth of Lactobacillus plantarum. When these compounds were added in combination to acidified cucumbers, the cucumbers were successfully preserved as indicated by the fact that neither yeasts or lactic acid bacteria increased in numbers nor were lactic acid or ethanol produced by microorganisms when cucumbers were stored at 30 oC for at least 2 months. This combination of two naturally occurring preservative compounds may serve as an alternative approach to the use of sodium benzoate or sodium metabisulfite for preservation of acidified vegetables without a thermal process.