Biovalorisation of spent Konacha tea leaves via single-culture fermentation involving wine yeasts and lactic acid bacteria

• Published in: Journal of applied microbiology 2022-06
• Main Authors: Tang, Vivien Chia Yen, Sun, Jingcan, Pua, Aileen, Goh, Rui Min Vivian, Huang, Yunle, Ee, Kim Huey, Lassabliere, Benjamin
• Format: Article
• Language: English
• ISSN: 1365-2672
• DOI: 10.1111/jam.15650

The objective of this study was to explore the potential of fermentation as a biovalorisation strategy for spent tea leaves (STL), a major agri-food waste generated from the tea extraction industry. Fermentation by wine yeasts or lactic acid bacteria (LAB) have shown promising results in previous studies across various substrates. Konacha (green tea) STL slurries were inoculated with single strains of wine yeasts or LAB, respectively. After a 48-h fermentation, changes in selected non-volatile and volatile compositions were evaluated. Fermentation by LAB increased organic acid content by 5- to 7-fold (except Lactobacillus fermentum) and modulated the composition of major tea catechins, while wine yeast fermentation resulted in a 30% increase in amino acid content. Strain-specific production of specific volatile compounds was also observed, such as butanoic acid (L. fermentum), isoamyl acetate (Pichia kluyveri) and 4-ethylphenol (L. plantarum). Both volatile and non-volatile compound compositions of Konacha STL were successfully modified via wine yeast and LAB fermentation. Our findings indicate that Konacha STL is a suitable medium for biovalorisation by wine yeasts or LAB via the generation of commercially useful volatile and non-volatile compounds. Future optimizations could further render fermentation an economically viable strategy for the upcycling of STL.