The aim of this study was to evaluate the probiotic properties of lactic acid bacteria (LAB) isolated from kimchi and antioxidant and anti-inflammatory activities of heat-killed LAB strains. Regarding probiotic properties, Lactiplantibacillus plantarum SMF398 and L. plantarum SMF470 isolated from kimchi can survive under artificial gastric condition and adhere strongly to HT-29 cells. The SMF398 and SMF470 strains showed strong antimicrobial activity and co-aggregation against pathogenic bacteria. The heat-killed cells of LAB (1 mg/mL) were prepared by heating at 121℃ for 15 min. MTT assay revealed that the heat-killed cells (1 mg/mL) of SMF398 and SMF470 were not toxic to HT-29 cells. The heat-killed SMF398 and SMF470 showed significantly higher DPPH and ABTS radical scavenging activities as well as β- carotene bleaching inhibitory activity than the heat-killed L. plantarum ATCC14917, a control probiotic strain (p<0.05). In lipopolysaccharide-induced RAW264.7 cells, the heat-killed SMF398 and SMF470 significantly reduced the nitric oxide production by 30.92% and 22.81%, respectively (p<0.05). Furthermore, the heat-killed SMF398 and SMF470 significantly decreased the gene expression levels of tumor necrosis factor-α, interleukin-6, inducible nitric oxide synthase, cyclooxygenase-2 up to 58.02%, 67.70%, 53.44%, 45.90%, respectively (p<0.05). These results suggest that the heat-killed L. plantarum SMF398 and L. plantarum SMF470 might be useful as antioxidant and anti-inflammatory agents.

This study aimed to investigate the effects of antioxidant and anti-inflammatory activities of heat-killed lactic acid bacteria (LAB) produced under different temperature conditions. Regarding probiotic properties, Limosilactobacillus fermentum SMF743 and Lactiplantibacillus plantarum SMF796 isolated from kimchi showed strong acid and bile salt resistance, adhesion activity onto HT-29 cells, and antimicrobial activity against pathogenic bacteria. Based on the results of thermal death time and temperature, heat-killed LAB cells (1 mg/mL) were prepared by heating at 70oC (180 min), 80oC (120 min), 100oC (30 min), and 121oC (15 min). The heat-killed SMF743 and SMF796 showed significantly higher DPPH and ABTS radical scavenging activities than live cells (p<0.05). The heat-killed SMF743 and SMF796 at 70oC or 121oC revealed stronger DPPH and ABTS radical scavenging activities and inhibition of nitric oxide production than those at 80oC or 100oC. Furthermore, heat-killed SMF743 and SMF796 at 121oC significantly reduced the gene expression levels of tumor necrosis factor-, inducible nitric oxide synthase, and cyclooxygenase- 2 up to 53.33%, 58.67%, and 83.67%, respectively, in lipopolysaccharide (LPS)-induced RAW264.7 cells (p<0.05). These results suggest that heat-killed L. fermentum SMF743 and L. plantarum SMF796 can be used as natural antioxidants and anti-inflammatory agents.

This study aimed to optimize the fermentation condition of black bean using probiotic lactic acid bacteria (LAB) and to evaluate characteristics and antioxidant activity of LAB fermented and heat-treated black bean. Two LAB strains were selected by analysis of acid resistance, bile resistance, antimicrobial activity, and antioxidant activity, and identified as Lactiplantibacillus plantarum CH9 and Lactiplantibacillus plantarum SU18 by 16S rRNA sequencing. Both strains showed similar or higher acid resistance, bile resistance and antimicrobial activity, compared to Lacticaseibacillus rhamnosus GG, a commercial probiotic strain. The heat-killed cells of CH9 and SU18 strains showed significantly (p<0.05) higher DPPH and ABTS radical scavenging activities than live cells. Fermentation of black bean (30%) treated with Alcalase using the two selected strains was found to be optimal condition, increasing viable cell count of LAB up to 10.8 Log CFU/g. During the fermentation, the titratable acidity of Alcalase-treated black bean was notably increased with concomitant decrease in the pH. LAB fermentation significantly (p<0.05) increased antioxidant activity based on DPPH and ABTS radical scavenging activities as well as total phenol content. In addition, total phenol content and antioxidant activity were significantly (p<0.05) enhanced by heat processing (121C, 15 min) of the fermented products. These findings are expected to be useful for the development of various LAB-fermented foods containing heat-killed probiotics.

김치로부터 내산성, 내담즙성 및 항산화활성이 우수한 유산균을 분 리하였으며, 프로바이오틱스 활성이 우수한 2종의 균주를 스타터 로 선정하여 고농도의 홍삼 추출물이 보강된 요구르트를 제조하고, 그 품질특성을 평가하였다. 가정에서 제조된 배추김치로부터 분리 한 L. plantarum SY46과 L. brevis SY65 균주는 인공위액과 담 즙염에 대한 저항성, 병원균에 대한 항균활성 및 항산화활성이 상 업용 프로바이오틱스 균주인 L. rhamnosus GG(LGG)와 비교하 여 우수하였으며, auto-aggregation과 co-aggregation 능력은 유사한 특성을 나타내었다. 홍삼 추출분말 5%와 10%가 각각 첨가 된 우유에 SY46과 SY65의 복합 균주를 접종하고 24시간 발효한 결과, 홍삼 요구르트의 pH는 각각 4.46과 4.28, 산도는 1.25%와1.53%, 유산균 생균수는 9.26와 9.90 Log CFU/mL를 나타내었다. 홍삼의 첨가량이 증가할수록 DPPH 라디칼 소거능과 β-carotene bleaching 억제능이 증가되어, 유산균체의 항산화능과 더불어 홍 삼이 요구르트의 항산화능을 높이는데 기여하는 것으로 나타났다. 따라서 본 연구결과, L. plantarum SY46과 L. brevis SY65 균주 를 스타터로 활용하여 프로바이오틱스 및 홍삼의 기능성이 강화된 요구르트의 제조가 가능할 것으로 기대된다.

본 연구에서는 유산균에 의한 검은콩의 최적 발효조건을 확립하고 발효된 검은콩의 품질특성을 평가하였다. 가정에서 제조된 배추김치로부터 분리한 Lactobacillus plantarum SU22는 병원성 세균에 대해 강한 항균 활성을 보였고 생체 아민과 발암성 효소인 β-glucuronidase를 생성하지 않았기 때문에 검은콩 발효의 스타터로 선정되었다. 검은콩은 5 kgf/cm2, 150oC로 조절된 팽화기에서 10분 동안 팽화 처리한 것과 처리하지 않은 것으로 각각 10- 30% 혼합액을 만들고 L. plantarum SU22를 1%(v/v) 접종하여 37oC로 48시간 동안 진탕 배양하면서 유산균의 생육 특성을 비교하였다. 유산균의 생균수는 L. plantarum SU22 로 발효된 팽화 검은콩(20%) 배양액에서 9 Log CFU/mL 이상이었다. 20% 팽화 검은콩 배양액을 alcalase로 가수분 해한 후 L. plantarum SU22로 발효하는 것이 최적 조건인 것으로 밝혀졌으며 유산균의 생균수가 10.30 Log CFU/ mL까지 증가하였다. 최적 조건에서 총 폴리페놀 함량(94.02 mg GAE/g)과 DPPH 라디칼 소거능(92.50%)이 비 발효 대조군(87.74 mg GAE/g, 83.14%)에 비해 현저하게 증가하였다(P<0.05). 결론적으로 검은콩을 팽화한 후 alcalase 처리와 L. plantarum SU22를 병행하여 발효할 때 바이오제닉 아민이 없는 검은콩 발효액을 효과적으로 제조할 수 있으며, 총 폴리페놀과 DPPH 라디칼 소거능을 유의적으로 증가시킬 수 있다는 것을 알 수 있었다.