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Research Project: Improved Processes for the Preservation and Utilization of Vegetables, Including Cucumber, Sweetpotato, Cabbage, and Peppers to Produce Safe, High Quality Products with Reduced Energy Use and Waste

Location: Food Science Research

Title: Effect of brine acidification on fermentation microbiota and texture quality of cucumbers fermented in calcium chloride brines

item MCMURTRIE, ERIN - North Carolina State University
item Johanningsmeier, Suzanne
item Price, Robert
item Breidt, Frederick

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/28/2019
Publication Date: 5/1/2019
Citation: McMurtrie, E.K., Johanningsmeier, S.D., Price, R.E., Breidt, F. 2019. Effect of brine acidification on fermentation microbiota and texture quality of cucumbers fermented in calcium chloride brines. Journal of Food Science. 84(5):1129-1137.

Interpretive Summary: Bulk preservation of cucumbers relies on high salt concentrations that lead to excess salty wastewater during commercial production. Calcium chloride has been proposed as an alternative salt for fermentation that enables much lower salt concentrations to be used and results in an effluent that is safe for discharge onto land. This study examined the effects of initial brine acidification on the course of fermentation and resulting texture quality of cucumbers fermented in calcium brines. Acidification of the brine with acetic acid (the organic acid in vinegar) reduced the pH of the cucumber and the soil-associated Enterobacteriaceae spp most rapidly, but the texture quality was not affected by brine acidification despite the differences in early fermentation microbiota. All cucumbers fermented in calcium chloride brines (1.1% by weight) in the absence of air retained their firmness during fermentation and bulk storage.

Technical Abstract: Commercial fermentation for bulk preservation of cucumbers relies on natural microbiota and approximately 1 M sodium chloride (NaCl) brines, resulting in large volumes of high-salt wastewater. An alternative process utilizing 0.1 M calcium chloride as the only salt was developed to eliminate NaCl from fermentation brines for reduced environmental impact. This study determined the effect of brine acidification on the fermentation microbiota and texture quality of cucumbers fermented in calcium chloride brines. Cucumber fermentations were conducted in sealed glass jars for six independent lots of cucumbers in a randomized complete block design with a full-factorial treatment structure for brine acidification (acetic acid, hydrochloric acid, or nonacidified) and brining salt (1 M NaCl or 0.1 M calcium chloride). Enterobacteriaceae spp. survived longer and were >1 log colony forming units/mL higher in fermenting cucumbers than in brines. Addition of 25 mM acetic acid to fermentation brines (but not the addition of hydrochloric acid at the same pH) reduced Enterobacteriaceae spp. in brines and cucumbers (P < 0.002) during the initiation of fermentation for both brining salts. However, acidification had no effect on texture quality of fermented cucumbers (P = 0.8235). Despite differences in early fermentation microbiota, fermentation of cucumbers in calcium chloride brines under controlled conditions, with or without acidification, resulted in high retention of tissue firmness. These results differ from fermentations in a commercial setting initiated in brines of neutral pH, indicating that production variables, such as air exposure, interact with brining in calcium chloride to negatively affect the texture quality of fermented cucumbers.