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United States Department of Agriculture

Agricultural Research Service

Research Project: PROCESS-READY CUCUMBER PRESERVATION BY ACIDIFICATION WITH LESS THAN 2.4% ACETIC ACID

Location: Food Science Research

2013 Annual Report


1a.Objectives (from AD-416):
To evaluate a cucumber preservation method that would allow the processing of the preserved fruits without washes prior to packing into final product. The final cover brine formulation should preserve cucumbers for 9 months or more, and equilibrate with the fruits to contain about 1.1% acetic acid, reduced sodium chloride (4% or less), and pH 3.3 or lower.


1b.Approach (from AD-416):
ARS scientists developed reduced sodium chloride and acetic acid cover brine formulations to effectively preserve cucumbers at pH 3.5 for up to a year in the absence of oxygen. It is the intent of this research to scale up the successful treatments from such laboratory trials to commercial products imported to the United States. Although the presence of oxygen in the commercial packaging is likely to encourage microbial growth and make the preservation more difficult to achieve, treatments containing 1.1% acetic acid, 0.45% calcium chloride, 0- 4% sodium chloride, and combinations of either traditional preservatives such as potassium sorbate and sodium benzoate or natural preservatives, and fumaric acid will be tested. Phosphoric acid will be evaluated as an additional ingredient to achieve a pH of 3.3 or below, as the reduction of acetic acid to 1.1% will not make it possible to reach this target. Preliminary studies will be conducted concomitantly in the U.S. and an international processing facility with the aim of reducing the list of successful treatments, refine the cover brine formulations, and define the acidification needs for the preservation treatments to achieve a pH of 3.3. The evaluation of treatments in the United States would include the monitoring of microbial growth, primarily lactic acid bacteria, yeasts and molds, and enterobacteria, basic chemical analysis for sugars and organic acids, pH, titratable acidity and a single point texture evaluation. The evaluation of treatments from international processing facilities will include the monitoring of the development of pressure and turbidity, and the determination of pH and titration of acidity. Treatments identified as effective during the preliminary stage will be further evaluated in Phase 1 and polished in Phase 2 to develop a close to commercialization formulations. The evaluation of treatments during Phases 1 and 2 will proceed in the same fashion described above for the international preliminary trials.


3.Progress Report:

This project is related to in-house objective 2 targeting an increase in consumer acceptance of acidified vegetables that are refrigerated or preserved at ambient temperature without a thermal process by use of alternative acids and natural antimicrobial compounds to replace traditional preservatives, and by addition of probiotic lactic acid bacteria that provide health benefits to consumers.

This collaboration with Marcatus QED, and Mount Olive Pickle Company is now concluded. The objective of this project was to evaluate low acid and salt formulations for the long term preservation of cucumbers at the commercial scale that would reduce the chloride concentrations in waste waters generated in the US by local companies receiving products from India. Marcatus QED and Mount Olive Pickle Company located in Mount Olive, NC have been collaborating with ARS scientists to test the low salt and acid treatments at a semi-commercial scale with successful outcomes. The ability of fumaric acid and allyl isothiocyanate, the spicy component in horseradish and mustard, to preserve acidified cucumbers in reduced salt cover brines was confirmed at the semi-commercial scale locally. A combination of sodium benzoate and fumaric acid was also tested and proven to be effective in preserving by preventing microbial spoilage long term and in maintaining adequate texture and color retention. Experimental treatments containing lauric arginate were not successful in retaining texture and color long term or in preventing the proliferation of inoculated spoilage organisms. However, all the experimental treatments were more effective in achieving a 5-log reduction for Escherichia coli O157:H7 as compared to the traditional high acid and salt treatments containing sulfite as preservative at 30 °C.

Technology transfer activities for the low salt and acid preservation method were initiated. This stage included the testing of selected treatments at the commercial scale in India. Personnel at the international processor facility were trained by one of our local collaborators to apply the experimental treatments on-site (in India) following a systematic approach that can yield publication quality data, which may be used to support FDA process filing. Preserved fruits were shipped from India to Mount Olive Pickle Company for further processing by us. Microbiological, biochemical and texture analyses were conducted on the preserved cucumbers. Progress on this project was made as a team effort.


Last Modified: 9/10/2014
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