Methods for Maintaining and Using Lactic Acid Bacteria Starter Cultures for Commercial Cucumber Fermentation Brined...

We assessed frozen (-20°C) storage of lactic acid bacteria (LAB) in cryovials containing plastic beads known as Microbanks and developed a method for utilizing them in preparing starter cultures for commercial fermentations. Microbanks preserved Lactococcus lactis and Levilactobacillus brevis for 1 year, whereas Pediococcus spp. and Lactiplantibacillus pentosus and Lactiplantibacillus plantarum were viable for 22 months. The preserved LAB were resuscitated in cucumber, carrot, or sweet potato juice after 24-30 h of incubation at ambient temperature. Cucumber fermentation medium (CFM), used for the pre-adaptation of the starter cultures to 342 mM (2%) sodium chloride (NaCl), sustained the growth of the preserved LAB to maximum cell densities in 12-24 h. Pre-adaptation of cultures in 100 mL CFM supported quick acid production, but inoculation of up to 10 L of CFM with a 10 µL loop full of cells sufficed for a complete fermentation and biomass production. Cultures of Lc. lactis and L. plantarum reached maximum cell densities in CFM in 12 h, whereas L. pentosus presented a 2 h delay (14 h). Lev. brevis and Pediococcus spp. needed 16 h incubation to achieve maximum cell densities in CFM. Acid production by the LAB revived in CFM supplemented with 342 mM NaCl, 18 mM calcium chloride, and 18 mM calcium hydroxide reduced the pH to 5.60 ± 0.51 by the time they reached maximum cell densities. These observations led to a method for the maintenance of LAB in Microbanks in a household freezer, and for their use in preparing starter cultures for commercial cucumber fermentations. PRACTICAL APPLICATIONS: Implementation of commercial cucumber fermentations with reduced salt demands the utilization of starter cultures to guide fermentations to the endpoint, assure acid production, and prevent processing defects. The methods described here create opportunities for processors to generate starter cultures in-house for commercial-scale cucumber fermentations using functional strains isolated from such habitats.