Optimization of Tyrosinase Inhibitory Activity in the Fermented Milk by Lactobacillus plantarum M23

The melanin pigment in human skin is a major defense mechanism against ultraviolet light to the skin, but darken skin color. Tyrosinase is mainly responsible for melanin biosynthesis (melanogenesis) in animals and enzymatic browning (melanosis) in plants. The purpose of this study was to optimize the fermented milk process for the melanin formation inhibition by using Lactobacillus plantarum M23 with tyrosinase inhibitory activity. We used 4-factor-3-level central composite design combining with response surface methodology. Yeast extract concentration (%, $X_1$), addition of grape (%, $X_2$), incubation temperature ($^{\circ}C$, $X_3$) and incubation time (h, $X_4$) was used as an independent factor, on the other hand, pH (pH, $Y_1$), overall palatability (score, $Y_2$) and tyrosinase inhibitory activity (%, $Y_3$) was used as a dependant factor. Based on the optimization for the highest tyrosinase inhibitory activity with pH 4.4, the expected data of pH, palatability and tyrosinase inhibitory activity with 14.8 h incubation at $37.1^{\circ}C$ by the addition of 0.127% of yeast extract, 2.95% of grape was 4.42, 7.06 and 86.65%, but the real data was 4.35, 6.86 and 84.05%, respectively. Based on the previous results, fermented milk using Lactobacillus plantarum M23 with the tyrosinase inhibitory activity could contribute for the whitening and antiaging of human skin.

Lactobacillus plantarum M23 균주를 이용한 Tyrosinase 저해 활성 발효유 생산의 최적화

본 연구는 tyrosinase 활성 저해효과가 있는 젖산균인 L plantarum M23 균주를 이용하여 멜라닌 형성을 억제하기 위한 최적 발효유 제조조건을 설정하는데 그 목적이 있다. 3수준 4인자 중심합성 계획법을 통해 실험설계하여 반응표면분석법을 사용하였다. 독립변수로는 yeast extract 농도(%, $X_1$), 포도첨가량(%, $X_2$), 배양온도($^{\circ}C$, $X_3$), 배양시간(h, $X_4$)을 설정하였고, 종속변수로는 pH(pH, $Y_1$), 종합적 기호도(score, $Y_2$)와 tyrosinase inhibitory activity(%, $Y_3$)를 설정하였으며, tyrosinase inhibitory activity가 가장 높고 pH는 4.4를 동시에 만족하는 최적화를 실시한 결과 yeast extract 농도는 0.13%, 포도 첨가량은 2.95%, 배양 온도는 $37.1^{\circ}C$, 배양 시간은 14.8 h일 때 예상되는 pH는 4.42, 기호도는 7.06, tyrosinase inhibitory activity은 86.65%이었으며, 실제 실험 결과 pH는 4.35, 기호도는 6.86, tyrosinase inhibitory activity은 84.05%로서 큰 차이를 나타내지 않았다. 이러한 결과를 토대로 melanin 생합성과정의 key enzyme인 tyrosinase을 활성억제하는 L. plantarum M23을 이용한 발효유는 피부의 미백 작용과 노화 억제 작용에 기여할 것으로 사료되었다.