Safety of Kimchi and Bacteriocin Production

Kimchi has been eaten for centuries without causing any health problems. However, residual agricultural chemicals, pathogenic microorganisms, and NO2 levels in cabbages are public concerns. One study reported that agricultural chemicals such as an insecticide, chloropyrifos(O,O-diethyl-O-(3,5,6-trichloro-2-pyridyl)-phosphorothioate), can be removed during the process of manufacturing kimchi (23). Baechu cabbages that were soaked in the chlorpyrifos solution were used for kimchi preparation. The residual

0 8 16 24 32 40 48 56 64 72 90 0 8 16 24 32 40 48 56 64 72 80 Fermentation time (days) Fermentation time (days)

Figure 5 pH and acidity changes of kimchi during fermentation at different temperatures. (From Ref. 22.)

chlorpyrifos at 0.161 ppm in raw cabbages, decreased to 0.0938 ppm after 4 washings and then further decreased to 0.0099 ppm during the four-week fermentation.

Pathogenic microorganisms of the kimchi ingredients can be eliminated during fermentation. Park (24) examined the pathogenic microorganisms of factory-manufactured kimchi during storage at 0°C and 8°C for 41 days. The author could not detect E. coli, Staph. aureus, or Vibrio parahaemolyticus during the whole storage period; although, low levels of coliform bacteria were detected in the early stage of storage. The coliform bacteria level was 2.0 x 103 CFU/mL at 0 day but reduced to less than 10 count after 13 days at 8°C. The reduction of these microorganisms is likely due to the acidic and salt conditions and microbial competition during storage.

LAB in kimchi are known to inhibit the growth of pathogenic organisms. For example, Ped. cervisiae and Leuconostoc sp. are most effective in restricting the growth of pathogenic organisms, such as E. coli, Staph. aureus, and Bacillus cereus (25). Ped. cervisiae suppressed the growth of E. coli, Strep. faecalis, and Lac. bulgaricus (26). Using in vitro testing, the addition of ether extract from Lac. plantarum Lp2 isolated from kimchi culture

Table 5 Time Required for Optimum Kimchi Fermentation at Different Salt Concentrations and Temperatures (days)

Temperature (°C)

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