Effect of different tea types (Camellia sinensis) on antioxidant and sensory properties of kombucha fermentation

Ch'ng, Brian Wei Shen (2025) Effect of different tea types (Camellia sinensis) on antioxidant and sensory properties of kombucha fermentation. Final Year Project, UTAR.

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Abstract

Kombucha is a functional fermented tea beverage that has been gaining consumer interest due to its rich bioactive compounds. While green tea kombucha and black tea kombucha are well studied, limited research has focused on kombucha fermented with oolong tea (semi-oxidised) and dark tea (post-fermented), which have different phytochemical and flavour profiles. The study found that the types of tea, fermentation time, and their interaction significantly affected the total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activities (DPPH and FRAP) of kombucha. Green tea kombucha (GTK) consistently exhibited the highest TPC (up to 788.48 �} 5.84 mg GAE/L), TFC (up to 420.30 �} 2.92 mg QE/L), and antioxidant activities (up to 73.15 �} 0.38% in DPPH inhibition, 16.19 �} 0.07 mmol Fe2⁺/L in FRAP), followed by oolong tea kombucha (OTK) and dark tea kombucha (DTK). All samples exhibited a significant increase in phytochemical content and antioxidant activities by Day 7, followed by a decrease by Day 14. From Day 0 to Day 7, GTK had the highest increase in TFC (+159.39 mg QE/L) and FRAP (+4.44 mmol Fe2⁺/L), while the lowest increase was in DTK (+65.75 mg QE/L, +1.71 mmol Fe2⁺/L). From Day 7 to Day 14, the highest decreases in phytochemical content (–85.45 mg GAE/L, –53.03 mg QE/L) were observed in GTK, while the highest decreases in antioxidant activities (–4.24 %, –2.12 mmol Fe2⁺/L) were observed in OTK. In the sensory evaluation, GTK and OTK received significantly higher ratings for aroma, sourness, and overall acceptability than DTK, with no significant difference in colour and sweetness among all types of kombucha. Overall, GTK was more recommended due to its higher phytochemical content, antioxidant activities, and consumer acceptability.

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