Microbial Properties of Probiotic Fermented Milk Supplemented with Ginseng Extracts

Abstract

The therapeutic properties of Lactobacillus rhamnosus GR-1 and ginseng extracts have been well documented. The objective of this study was to measure growth and survival of L. rhamnosus GR-1 in milk fortified with ginseng extracts during storage period of 28 days. Five formulations of milk (1% fat) were prepared. Two samples were fortified with alcoholic ginseng extract (AGE: 150 μg/mL, AGE: 500 μg/mL) and the other two samples were fortified with aqueous ginseng extract (QGE: 150 μg/mL, QGE: 500 μg/ml) and one with no ginseng extract (C). The mixtures were auto- claved for 15 min, cooled to 37˚C and inoculated with 1% starter culture. The samples were then incubated anaerobi- cally at 37˚C overnight. Selective MRS agar containing 0.015 g/L fusidic acid was used to enumerate L. rhamnosus GR-1 after 1, 14, and 28 d storage at 4˚C. All ginseng-fortified samples supported the growth and survival of L. rham- nosus GR-1, as viable counts were detected at each measurement point throughout the 28 d storage period. After 1 d of storage, total colony counts for L. rhamnosus GR-1 in AGE: 150 μg/mL and AGE: 500 μg/mL were 1.3 × 109 and 1.4 × 109 CFU/mL, respectively; probiotic counts in QGE 150 μg/mL and QGE: 500 μg/mL were 1.5 × 109 and 1.4 × 109 CFU/mL, respectively. Additionally, L. rhamnosus GR-1 viability remained stable throughout the 28 days storage pe- riod, as no significant decrease (p < 0.05) in total colony counts were detected. The results indicate that L. rhamnosus GR-1 can remain viable in presence of ginseng extracts during storage period and there is potential for incorporating ginseng extracts in other probiotic dairy products.