Effect of a Nitrite-Degrading Lactococcus lactis Strain on Flavor and Quality of Kimchi
Kimchi is a common traditional fermented vegetable in northern China. Nitrite can be produced during the fermentation of kimchi,which is harmful to human health. In this study,a strain of Lactobacillus PG2-8 which can efficiently degrade nitrite (degradation rate of 96.13％) is screened from 120 strains of kimchi lactic acid bacteria. After 16S rRNA gene sequence analysis,it is identified as Lactococcus lactis. The strain is applied to the fermentation of kimchi,and its effect on the flavor and quality of kimchi is analyzed. Solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS) is used to analyze the volatile flavor substances of kimchi. A total of 56 flavor substances are determined,among which,eight flavor substances are identified as the potential marker substances that distinguish kimchi fermented by Lactococcus lactis PG2-8 from naturally fermented kimchi. After fermentation by Lactococcus lactis PG2-8,the sulfide concentration of kimchi decreases,the flavor and quality are significantly improved,and the fermentation period is shortened.The research results show that Lactococcus lactis PG2-8 has the potential to serve as a starter strain for fermenting kimchi.
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