Fermentative characteristics of yogurt using lactic acid bacteria isolated from Korean traditional fermented food

Abstract

The objective of this study was to select yogurt starter from Korean traditional fermented foods. The 2 strains (KM24, KM32) among 50 strains of isolated lactic acid bacteria selected as starter based on milk clotting ability, antimicrobial activity against various pathogens, tolerance in artificial gastric and bile juice and growth in 10 % skimmed milk. The strains were identified as Lacobacillus plantarum (KM32) and Pediococcus pentosacesus (KM24) by 16S rRNA gene sequencing. Viable cell number of yogurt fermented with mixed strains (KM24 and KM32) was 9.66 log CFU/mL after fermentation for 48 h and maintained 109 CFU/mL during fermentation for 72 h at 37°C. The pH and titratable acidity of mixed cultured yogurt were 4.25% and 0.83% after fermentation for 48 h at 37°C, respectively. The physico-chemical characteristics of mixed cultured yogurt after fermentation for 48 h were 38.45 μg/mL (polyphenol content), 48.57% (DPPH radical scavenging activity) and 465.40 cp (viscosity), respectively. The mixed cultured yogurt maintained 109 CFU/mL of lactic acid bacteria during storage 10 days at 4°C. The viable cell number of yogurt prepared with mixed culture(KM32+KM24) maintained higher and than that of control (L. casei) during storage. These results indicated the potential use of selected strains (KM32+KM24) isolated from kimchi as a yogurt starter with strong acid tolerance and probiotics properties.