Changes of Nutritional Components, Polyphenols, and Antioxidant Activities of Domestic Bamboo Tree (Sasa coreana Nakai) Leaves Fermented with Bacillus subtilis

Bacillus subtilis를 이용한 국내산 신이대 잎 발효에 따른 영양성분, 폴리페놀, 항산화능 변화

Bamboo leaf has many nutritional and bioactive compounds such as polyphenols, and it can be used for various foods application. Fermentation is one of appropriate processes that can affect the nutrition, taste and flavor, and antioxidant activities of foods. In this study, a representative domestic bamboo tree (Sasa coreana Nakai) leaves were fermented by Bacillus subtilis KCCM 11315 and the changes of carbohydrates, minerals, amino acids, and phenolic compounds and antioxidant activities were investigated before and after fermentation. During the fermentation period, firstly, the leaf was softened and turned to brown. The constituent carbohydrates were slightly increased from $432.09{\pm}5.38mg/g$ to $458.42{\pm}7.39mg/g$, and free sugars decreased by 95% from $28.12{\pm}2.03mg/g$ to $1.4{\pm}0.14mg/g$. Mineral was $20987.5{\pm}345.1{\mu}g/mL$, which was slightly increased after the fermentation compared to $20804.1{\pm}364.6{\mu}g/mL$ before that. The total amino acids were increased to $73881.94{\pm}137.59mg/100g$ compared to $58464.51{\pm}109.12mg/100g$ before fermentation, and free amino acids decreased by more than 85% from $32782.67{\pm}92.49mg/100g$ to $4827.83{\pm}19.76mg/100g$. Total polyphenols content (TPC) increased from $25.51{\pm}1.04GAE^*mg/g$ to $35.34{\pm}0.91GAE^*mg/g$, and the total flavonoid content (TFC) increased to $80.57{\pm}0.22QE^*mg/g$ compared to $69.64{\pm}0.26QE^*mg/g$. The total catechin content (TCC) of TFC was decreased from $69.64{\pm}0.94mg/L$ to $58.23{\pm}0.76mg/L$. The DPPH radical $IC_{50}$ of bamboo leaves decreased to $2624.85{\pm}37.03{\mu}g/mL$ and the ABTS radical $IC_{50}$ of $187.26{\pm}4.78{\mu}g/mL$ was increased after the fermentation. These results could be used as essential nutritional data before developing processed food products using the bamboo leaf.