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Title: Microbial ecology of watery kimchi

Author
item KYUNG, KYU HANG - SEJONG UNIVERSITY
item MEDINA-PRADAS, EDUARDO - INSTITUTO DE LA GRASA
item KIM, SONG GUN - KOREAN RESEARCH INSTITUTE OF BIOSCIENCE AND BIOTECHNOLOGY
item LEE, YONG JAE - KOREAN RESEARCH INSTITUTE OF BIOSCIENCE AND BIOTECHNOLOGY
item KIM, KYOUNG HO - PUKYONG NATIONAL UNIVERSITY
item CHOI, JIN JOO - SEJONG UNIVERSITY
item CHO, JOO HYOUNG - SEJONG UNIVERSITY
item CHUNG, CHANG HO - SEJONG UNIVERSITY
item BARRANGOU, RODOLPHE - NORTH CAROLINA STATE UNIVERSITY
item Breidt, Frederick

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/17/2015
Publication Date: 5/1/2015
Publication URL: http://handle.nal.usda.gov/10113/61023
Citation: Kyung, K., Medina-Pradas, E., Kim, S., Lee, Y., Kim, K., Choi, J., Cho, J., Chung, C., Barrangou, R., Breidt, F. 2015. Microbial ecology of watery kimchi. Journal of Food Science. 80(5):M1031-M1038.

Interpretive Summary: This study is unique in using high throughput DNA sequencing for microbial ecology studies to determine how the microbial ecology of kimchi fermentations was altered by changing the way the vegetables were prepared for fermentation and changing the fermentation conditions. These kimchi products are gaining popularity in the U.S. but little is known about how processing conditions affect the microbial ecology and, therefore, the safety and quality of the products. The data showed that thinly sliced vegetables accelerated the fermentation, and potentially improved the safety of the products, by increasing the rate at which fermentation occurs. Changes in fermentation temperature were also found to influence the microbial ecology. Lower temperatures, combined with thinly sliced vegetables, resulted in the most desirable fermentation conditions. The results may aid in understanding how preparation methods for vegetable fermentations affect quality and safety for a variety of products.

Technical Abstract: The biochemistry and microbial ecology of 2 similar types of watery (mul) kimchi, containing sliced and unsliced radish and vegetables (nabak and dongchimi, respectively), were investigated. Samples from kimchi were fermented at 4, 10, and 20 °C were analyzed by plating on differential and selective media, high-performance liquid chromatography, and high-throughput DNA sequencing of 16S rDNA. Nabak kimchi showed similar trends as dongchimi, with increasing lactic and acetic acids and decreasing pH for each temperature, but differences in microbiota were apparent. Interestingly, bacteria from the Proteobacterium phylum, including Enterobacteriaceae, decreased more rapidly during fermentation at 4 °C in nabak cabbage fermentations compared with dongchimi. Although changes for Proteobacterium and Enterobacteriaceae populations were similar during fermentation at 10 and 20 °C, the homolactic stage of fermentation did not develop for the 4 and 10 °C samples of both nabak and dongchimi during the experiment. These data show the differences in biochemistry and microbial ecology that can result from preparation method and fermentation conditions of the kimchi, which may impact safety (Enterobacteriaceae populations may include pathogenic bacteria) and quality (homolactic fermentation can be undesirable, if too much acid is produced) of the product. In addition, the data also illustrate the need for improved methods for identifying and differentiating closely related lactic acid bacteria species using high-throughput sequencing methods.