A Lactococcus lactis starter culture reduces the bloater defect in cucumber fermentations brined with low salt

Authors: Perez Diaz, Ilenys; BLOUIN, BENJAMIN - North Carolina State University; PAGAN-MEDINA, CHRISTIAN - Former ARS Employee

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/25/2025
Publication Date: 9/29/2025
Citation: Perez Diaz, I.M., Blouin, B., Pagan-Medina, C. 2025. A Lactococcus lactis starter culture reduces the bloater defect in cucumber fermentations brined with low salt. Journal of Food Science. 90. https://doi.org/10.1111/1750-3841.70490.
DOI: https://doi.org/10.1111/1750-3841.70490

Interpretive Summary: Pickling preserves cucumbers for year-round access and consumption and contributes more than 2 billion dollars to the US economy. Like fresh vegetables, the production of pickles is a growing economic sector which registered a 3.5% increase in 2019. Processors in Michigan, Wisconsin, California, North Carolina, and other states face challenges in preventing defects during cucumber pickle processing, such as the formation of internal holes from microbial gas production during fermentation. Such defect causes losses as high as 40% of a fermentation vessel, which is valued at $15,000 to $20,000. ARS scientists in North Carolina discovered that a food grade beneficial bacterium, Lactococcus lactis, is capable of outcompeting other bacteria naturally present in cucumber fermentation, and help reduce the incidence of bloater defect and economic losses. We aim at identifying a Lactococcus lactis complimentary starter culture to prevent bloater defect in cucumber fermentation brined with low salt and the consequent economic losses for processors across the USA.

Technical Abstract: The cucumber intrinsic Enterobacter and Leuconostoc generate sufficient carbon dioxide (CO2) in early fermentation, particularly those brined with low salt, to induce bloater defects prior to the onset of Lactiplantibacillus pentosus. Because of the Lactococcus lactis short doubling time, it is proposed as a starter culture for cucumber fermentation brined with low salt to prevent bloater defects. A screening of putative decarboxylases (27) in the cucumber fermentation bacteriome identified substantially more of such enzymes in Enterobacteriaceae (24 or 89%) relative to lactic acid bacteria (10 or 37%). Co-inoculation of Lc. lactis and Leuconostoc or Enterobacter in Cucumber Juice Medium (CJM) resulted in reduced formation of acetic acid and ethanol. The Enterobacter population suffered a 4.7 log of CFU/ml of CJM reduction by 22 h when co-inoculated with Lc. lactis. A reduction in CO2 production and bloater index, from 32.1 ± 9.5 to 2.9 ± 0.9, was observed in the fermentation of pasteurized cucumbers co-inoculated with Lc. lactis and Enterobacter cancerogenus or Leuconostoc lactis. However, bloater index increased in such fermentations when Leuconostoc fallax and Lc. lactis were co-inoculated. Fresh cucumber fermentations brined with low salt and inoculated with Lc. lactis, but not in combination with Lp. pentosus, resulted in reduced bloater defects. It is concluded that, a mixed starter culture of Lc. lactis with a lactic acid bacterium, other than Lp. pentosus may be useful in preventing bloater defects in cucumber fermentation brined with low salt.