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ARS Home » Southeast Area » Raleigh, North Carolina » Food Science Research » Research » Publications at this Location » Publication #139435
Title: Bulk tank technology: Acidification of commercially fermented cucumbers in bulk tanks to increase microbial stability

Author
item Fleming, Henry
item HUMPHRIES, ERVIN - NCSU
item THOMPSON, ROGER - 6645-10-00
item McFeeters, Roger

Submitted to: Pickle Pak Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2002
Publication Date: 11/1/2002
Citation: Fleming, H.P., Humphries, E.G., Thompson, R.L., McFeeters, R.F. 2002. Bulk tank technology: Acidification of commercially fermented cucumbers in bulk tanks to increase microbial stability. Pickle Pak Science. VIII:38-43.

Interpretive Summary: Commercially brined cucumbers held in large tanks are subject to spoilage if the salt concentration and level of acidity are too low. We found that acidification can be used to increase the stability of brined cucumbers, without increasing the concentration of salt. We found the optimum pH (an indication of acidity that is determined instrumentally) for increasing microbial stability without adversely affecting product firmness to be pH 3.5. Hydrochloric acid, a relatively inexpensive acid, was used to adjust the pH of the brine from higher values to the recommended 3.5 value. This information will be useful to pickle processors who wish to minimize salt usage and related waste disposal problems.

Technical Abstract: Ten commercial fiberglass tanks (8,000 gal) of size no. 1 fermented cucumbers were acidified with 5.46N HCl to lower the brine pH to 3.5 from the pH that resulted at the end of fermentation (3.65-3.70). The volume of hydrochloric acid required to do this varied from 8.9-14.8 gal per tank. The rate of attainment of pH equilibrium after acid addition varied by tank location, but was complete within about 4 hr. Samples of brine-stock and cover brine from each of the 10 tanks were adjusted to pH 3.5, 4.0, and unadjusted and were stored in glass jars under laboratory conditions. Over a 14-month storage period at room temperature, the brines adjusted to pH 3.5 were more stable in chemical composition than the unadjusted, and much more so than the pH 4.0-adjusted samples, based on chemical changes. Chemical changes that indicated microbial instability were characterized by a rise in pH and CO2 and acetic acid concentrations, and a reduction in lactic acid concentration. The data indicated that lowering the pH of the brine to 3.5 after fermentation from higher levels can help to increase microbial stability of brined cucumbers at relatively low salt concentrations without serious adverse effects on cucumber firmness.