Effects of solid-state fermentation with Bacillus subtilis LK-1 on the volatile profile, catechins composition and antioxidant activity of dark teas

Leike Xiao; Chenghongwang Yang; Xilu Zhang; Yuanliang Wang; Zongjun Li; Yulian Chen; Zhonghua Liu; Mingzhi Zhu; Yu Xiao

doi:10.1016/j.fochx.2023.100811

Effects of solid-state fermentation with Bacillus subtilis LK-1 on the volatile profile, catechins composition and antioxidant activity of dark teas

Food Chem X. 2023 Jul 28:19:100811. doi: 10.1016/j.fochx.2023.100811. eCollection 2023 Oct 30.

Authors

Leike Xiao¹, Chenghongwang Yang¹, Xilu Zhang¹, Yuanliang Wang¹, Zongjun Li¹, Yulian Chen², Zhonghua Liu^{3

4}, Mingzhi Zhu^{3

4}, Yu Xiao^{1

3}

Affiliations

¹ College of Food Science and Technology, Hunan Agricultural University, Changsha 410128, China.
² College of Animal Science and Technology, Hunan Agricultural University, Changsha 410128, China.
³ Key Laboratory of Ministry of Education for Tea Science, College of Horticulture, Hunan Agricultural University, Changsha 410128, China.
⁴ National Research Center of Engineering Technology for Utilization of Botanical Functional Ingredients, Hunan Agricultural University, Changsha 410128, China.

Abstract

In this study, the solid-state fermentation (SSF) of dark tea was carried out using Bacillus subtilis LK-1, which was isolated from Fu brick tea (FBT). The effects of SSF with B. subtilis on volatile organic compounds (VOCs), non-volatile metabolites, and antioxidant activities of dark tea was investigated. A total of 45 VOCs were identified, primarily consisting of ketones (18), hydrocarbons (8), aldehydes (7), and alcohols (6). Following fermentation, the content of key odor active substances such as linalool, β-ionone, and 3,5-octadiene-2-one significantly increased, resulting in an enhanced floral and fruity aroma of dark tea. Furthermore, new flavor substances like geranyl isovalerate and decanal were produced during SSF, enriching the aroma profile of dark tea. Non-ester catechins demonstrated a drastic increase, while ester catechins remarkably decreased after SSF. Furthermore, SSF led to a slight decrease in the total polyphenols content and antioxidant activity of dark tea. There is a close relationship between VOCs and the main non-volatile metabolites during SSF. Overall, this study highlighted the great impact of SSF with B. subtilis on the metabolites of dark tea and provided valuable insights into the role of bacteria in shaping the metabolite profile of FBT.

Keywords: Bacillus subtilis; Catechins composition; Dark tea; Multivariate statistical analysis; Solid-state fermentation; Volatile organic compounds.