GRAS 등급 미생물용 식용배지의 개발과 이를 활용한 천연식품보존제의 개발과 응용

Abstract

This study was investigated to develop edible-media for GRAS microorganisms (Lactobacillus plantarum AF1, Lb. plantarum HD1, Lb. plantarum EM, Leuconostoc citreum GR1, Leu. mesenteroides TA, and Bacillus subtilis SN7) using Chinese cabbage waste (CW) and salted Chinese cabbage waste (SCW) produced during the kimchi making process at homes, small businesses, and conglomerates. The collected CW and SCW were analyzed for their characteristics such as pH, titratable acidity, crude proteins, and free amino acids. As a result, there was no significant difference between the CW and SCW collected in accordance with location and season. The prepared CW and SCW juices were used as medium for GRAS microorganisms. After addition of corn steep liquor, glucose, and inorganic salts to the CW and SCW juices, pH levels were adjusted to the optimum pH for the strain. When Lb. plantarum AF1 was cultured in CW medium at 30℃ for 24 hr, growth was 9 log CFU/mL, antibacterial activity was 160 AU/mL, and antifungal activity was 640 AU/mL. These values are almost the same as the values observed in MRS medium. Under SCW medium, viable cell number and antimicrobial activities of Lb. plantarum AF1 were the same in MRS medium. The four lactic acid bacteria strains also showed the same viable cell numbers and antimicrobial activities under CW or SCW medium. When B. subtilis SN7 was cultured under CW medium, viable cell number (108CFU/mL)andantibacterialactivityagainstB. cereus (1,600 AU/mL) were the same values in TSB medium. Antifungal activity against A. ochraceus (2,560 AU/mL) was higher than that in TSB medium (640 AU/mL). The pH stability (pH 3.0∼9.0) and thermal (37℃∼121℃) and enzyme stabilities of the antimicrobial materials were investigated in accordance with the respective medium. As a result, it was confirmed that there was no difference in antimicrobial materials produced in the laboratory and edible medium (CW and SCW medium). Natural antimicrobial materials derived from GRAS microorganisms in edible medium (CW and SCW medium) were investigated to control film-forming yeast of kimchi. Yeast colonies could be observed on the surface of control kimchi (not treated), grapefruit seed extract-treated kimchi, and Lb. plantarum AF1 culture supernatant of CW medium after 15, 20, and 30 days of incubation at 4℃, respectively. This result demonstrates that the anti-yeast compounds from Lb. plantarum AF1 could be used as a bio-preservative, which can prevent film-forming yeasts in kimchi. In order to control B. cereus in chungkukjang, culture supernatant of B. subtilis SN7 in SCW medium was added. As a result, B. cereus was completely controlled after 2 days of incubation at 37℃. This study developed a low-cost food grade medium for GRAS microorganisms using CW and SCW, which was confirmed as a food bio-preservative.