Microbial interactions associated with secondary cucumber fermentation

Authors

  • W. Franco,

    1. Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Raleigh, NC, USA
    Current affiliation:
    1. Department of Chemical Engineering and Bioprocesses, Pontificia Universidad Católìca de Chile, Santiago, Chile
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  • I.M. Pérez-Díaz

    Corresponding author
    1. SAA Food Science Research Unit, Agricultural Research Service, U.S. Department of Agriculture, North Carolina State University, Raleigh, NC, USA
    • Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Raleigh, NC, USA
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  • Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the US Department of Agriculture or North Carolina Agricultural Research Service, nor does it imply approval to the exclusion of other products that may be suitable.

Correspondence

Ilenys M. Pérez-Díaz, US Department of Agriculture, Agricultural Research Service, SAA Food Science Research Unit, 322 Schaub Hall, Box 7624, North Carolina State University, Raleigh, NC 27695-7624, USA. E-mail: Ilenys.Perez-Diaz@ars.usda.gov

Abstract

Aims

To evaluate the interaction between selected yeasts and bacteria and associate their metabolic activity with secondary cucumber fermentation.

Methods and Results

Selected yeast and bacteria, isolated from cucumber secondary fermentations, were inoculated as single and mixed cultures in a cucumber juice model system. Our results confirmed that during storage of fermented cucumbers and in the presence of oxygen, spoilage yeasts are able to grow and utilize the lactic and acetic acids present in the medium, which results in increased brine pH and the chemical reduction in the environment. These conditions favour opportunistic bacteria that continue the degradation of lactic acid. Lactobacillus buchneri, Clostridium bifermentans and Enterobacter cloacae were able to produce acetic, butyric and propionic acids, respectively, when inoculated in the experimental medium at pH 4·6. Yeast and bacteria interactions favoured the survival of Cl. bifermentans and E. cloacae at the acidic pH typical of fermented cucumbers (3·2), but only E. cloacae was able to produce a secondary product.

Conclusions

The methodology used in this study confirmed that a complex microbiota is responsible for the changes observed during fermented cucumber secondary fermentation and that certain microbial interactions may be essential for the production of propionic and butyric acids.

Significance and Impact of the Study

Understanding the dynamics of the development of secondary cucumber fermentation aids in the identification of strategies to prevent its occurrence and economic losses for the pickling industry.

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