The purpose of this study is to evaluate antimicrobial effects of organic acid and some natural occurring antimicrobials against Staphylococcus aureus isolated from various origins (vegetables, peanut, pea leaf, kim- bab, person, perilla leaf, and animal) and to calculate their MIC and MBC values. Five organic acids (acetic, lactic, citric, malic, and propionic acid), three essential oils (carvacrol, thymol, and eugenol), and two other natural antimicrobials (nisin and cinnamic acid) were evaluated for their antimicrobial effects against 113 strains of S. aureus using combination treatments. Propionic acid (7%), nisin (1%), thymol (1%), carvacrol (1%) showed antimicrobial activities against S. aureus strains in agar disc diffusion test. And, carvacrol, thymol, and nisin were found to be the most effective with the lowest MIC values of 0.0313%, 0.0625%, and 0.0625% against S.aureus, respectively. Propionic acid (0.2313%) and citric acid (0.6000%) were the most effective among organic acids tested. Therefore, these five antimicrobials were selected for next combination treatments. Combination of propionic acid and citric acid were showed the strongest inhibitory effectiveness against S. aureus among combination treatments. These results suggest that organic acid such as propionic and citric acid, and natural occurring antimicrobial such as nisin, carvacrol, and thymol might be possibly used as preservatives for inhibiting S. aureus in foods.

We investigated eight active natural antimicrobials for preservation of functional beverages that are usually degraded by yeasts rather than by bacteria due to a high sugar content and a low pH. Five strains of yeasts (S. cerevisiae, Z. bailii, P. membranaefaciens, C. albicans, and P. Anomala) were tested with eight natural antimicrobial agents (ε-polylysine, yucca extract, vitamin B1 derivative, scutellaria baicalensis extract, chitooligosaccharid, allyl isothiocyanate, sucrose-fatty acid ester, and oligosaccharide). The lowest minimal inhibitory concentrations (MIC) were 10 ppm for oligosaccharide and sucrose-fatty acid ester against S. cerevisiae and Z. bailii, 10 ppm for allyl isothiocynate against P. membranaefaciens and C. albican, and 10 ppm for allyl isothiocynate and oligosaccharide against P. anomala . No growth were observed for five kinds of yeasts in functional beverages containing sodium benzonate at concentration of 0.015% or higher. The resistance of S. cerevisiae, Z. bailii, and P. Anomala against natural antimicrobial agents was lower than those of P. membranaefaciens and C. albican. Allyl isothiocyanate, oligosaccharide, and sucrose- fatty acid ester showed the highest antimicrobial activities among the eight tested antimicrobials. These results can be applied to develop new natural antimicrobial agents to improve microbial quality of functional beverages.

Antifungal activity of seven natural antimicrobials, such as ε-polylysine, extract of Yucca shidigera, TLS (vitamin B1 derivative), BMB-FS, chitooligosaccharide, KDSP 001, and KDSP 002 were investigated for their applications in functional beverage. Five fungi including Aspergillus niger, Penicillium citrinum, Rhizopus oryzae, Fusarium moniliforme, and Mucor rouxii were applied as test fungi and mininum inhibitory concentrations (MICs) of antimicrobials were examined. TLS exhibited the strongst antifungal activity among tested antimicrobials and the growth of all fungi was inibited at 100 ppm. The antifungal activity of BMB-FS appeared different. The growth of Fusarium moniliforme was inhibited by BMB-FS at 100 ppm, but it exhibit antifungal activity on P. citrinum, and M. rouxii at 1000ppm. MICs of TLS appeared to be 60 ppm for four test fungi except A. niger (100 ppm). These results indicate the possible usage of TLS and BMB-FS as natural antimicrobials in functional beverage.

The purpose of this study was to investigate the antimicrobial activities of natural antimicrobials (10 formulas, F1~F10) against yeasts in functional beverages. The growth rates of yeasts were different with the ten different natural antimicrobial formulas tested. Yeasts grew for 14 days and the antimicrobial effect was observed between 14 and 18 days. Levels of S. cerevisiae, Z. bailii, and P. membranaefaciens were reduced to the limit of detection (ND) < 10 CFU/mL) after 28 days. Resistance against the antimicrobial effect was greatest for P. membranaefaciens, which grew to a level of 0.12~1.48 log10 CFU/mL after 14 days and was reduced to a level of 1.61~3.55 log10 CFU/mL after 28 days. The resistance of C. albicans was also high with a growth level of 0.13~1.28 log10 CFU/mL after 14 days and reduction to 1.51~5.30 log10 CFU/mL after 28 days. The antimicrobial effect of F10 was strongest for P. membranaefaciens. Every treatment reduced the microbial levels to 2.68~5.62 log10 CFU/mL after 6 months. F2, F4, F5, F6, and F10 reduced the C. albicans level to ND after 28 days while F1, F3, F8, and F9 reduced yeasts to the ND level after 6 months. The antimicrobial activities observed here will be useful for development of natural antimicrobials.

도체표면에서 분리한 E. coli O157;H7 CDF1, A. sobria CDF3, S. aureus CDF2의 성장을 억제하기 위한 방안을 검토하였다. E. coli O157:H7 CDF1와 A. sobria CDF3는 NaCl 4% 이상 농도에서 성장이 억제된 반면 lactic acid 0.1%는 성장에 영향을 미치지 않았다. S. aureus CDF2은 NaCl 농도 4%에 의해 성장이 뚜렷하게 억제되지 않았으나 lactic acid 0