Quality of Cucumbers Fermented in Acidified and Non Acidified Calcium Chloride Brines for Reduced Environmental Impact of Brining Operations.
MCMURTRIE, ERIN KELLY. Quality of Cucumbers Fermented in Acidified and NonAcidified Calcium Chloride Brines for Reduced Environmental Impact of Brining Operations. (Under the direction of Dr. Suzanne Johanningsmeier) Commercial fermentation processes for the bulk preservation of cucumbers rely on natural microbiota and brines that equilibrate to 0.9 1.4 M sodium chloride (NaCl) producing large volumes of wastewater with high salt concentrations. An alternative fermentation process utilizing 0.1 M calcium chloride (CaCl2) as the only salt has been developed to eliminate NaCl from fermentation brines to reduce the environmental impact of brining operations. The objective of this study was to determine cucumber texture quality, color, and physical defects encountered during normal production routines using the two processes. This was accomplished by evaluating the mesocarp firmness, CIELAB colorimeter values and bloater indices for the two brining processes at the raw product, fermented and bulk stored, desalted, and finished product stages of commercial production. Fermentations with the current commercial NaCl process (n=27) used recycled brines with sufficient NaCl, CaCl2, and potassium sorbate to equilibrate with the cucumbers to 1 M, 0.04 M, and 2 mM, respectively as well as organic acids and volatile compounds carried over in the recycled brines. The fermentations with the CaCl2 process (n=41) used fresh brines with sufficient CaCl2 and potassium sorbate to equilibrate to 0.1 M and 6 mM, respectively, and was inoculated with a Lactobacillus plantarum starter culture at 10 6 CFU/mL. Cucumbers fermented with the NaCl process were significantly firmer by 1.7 N (P 0.0001) after fermentation and bulk storage. Longer bulk storage times were correlated with significantly less firm cucumbers in both processes by 0.74 N/100 days (P 0.0030) Cucumbers fermented with the CaCl2 process had significantly decreased chroma (intensity) and increased hue (P 0.0269) These differences first appeared after fermentation and bulk storage indicating that the quality changes were a result of a process occurring at that stage. Lactic and acetic acid concentrations were significantly higher in the NaCl process than in the CaCl2 process, likely because of the acid incorporated into the fermentation by the reuse of spent brines. This resulted in a different fermentation environment as compared to the initial, neutral pH of the CaCl2 process. Brine acidity has the potential to impact the microbial ecology, activity of pectinolytic enzymes, non enzymatic softening, and preservative efficacy. Therefore, laboratory fermentations were conducted with size 2B cucumbers in 946 mL jars using a full factorial design for salt (CaCl2 and NaCl) and acid (acetic acid, hydrochloric acid, and non acidified) to determine the effect of brine acidification on the fermentation microbiota and texture quality of cucumbers fermented in each brine. Fermentations were inoculated with 10 6 CFU/mL Lactobacillus plantarum and included 4 mM potassium sorbate, a common yeast and mold inhibitor. Lactic acid bacteria grew faster and to greater cell counts in the CaCl2 brines, resulting in increased utilization of fermentable sugars and production of more lactic acid than in NaCl brined fermentations (P 0.0084) Addition of 25 mM acetic acid to fermentation brines (but not the addition of HCl at the same pH) reduced Enterobacteriaceae spp. in brines and cucumbers during the initiation of fermentation for both brining salts (P 0.002) However, acidification had no effect on texture quality of fermented cucumbers for either brining salt (P 0.8235) Interestingly, cucumber firmness was 2.9 N higher in CaCl2 brined cucumbers compared to those brined in NaCl and stored for 100 days (P 0.0001) These results differed from the commercial trials, indicating that there are production variables not present on the laboratory scale interacting with the CaCl2 process to negatively affect texture quality. Of the commercial fermentations using the CaCl2 process, 12% had an average mesocarp firmness below acceptable quality levels, indicating a need for further optimization of this process.