Physicochemical and microbial characterization of kombucha and scoby-formulated jam from black, oolong and green teas

This research was aimed at diversifying kombucha fermentation and leveraging its by-product scoby for jam formulation, followed by a detailed microbial analysis of the resulting products. The initial phase of the study showed that different pure and combinations of teas, i.e., black, oolong and green teas are potential alternatives for kombucha fermentation as all samples exhibited similar physicochemical trends to conventional black tea. Throughout fermentation, refractometric analysis of brix declined while acidity, alcohol and total polyphenol content increased, resulting in a pH drop to 2.70-2.79. After a 10-day fermentation, scoby yield ranged 64.89-109.93%. Pure oolong tea, with its highest total polyphenol content, presented the highest scoby yield and outperformed pure black and green teas with the highest acetic acid and scoby formation rates using modified Gompertz model. Other models, i.e., Boltzmann, polynomial, rational and exponential effectively analysed substrate and pH changes (R2 > 0.96). Scoby harvested from black, oolong and green tea kombucha fermentation was incorporated into mango jams at 2-10%, resulting in enhanced quality by significantly (P < 0.05) reducing water activity (0.679-0.846), moisture content (19.92-29.48%), pH (3.19-3.38) and increasing brightness (31.82- 40.83), with more pronounced effects at higher scoby concentrations. Jam texture properties increased with scoby concentrations, showing pseudoplasticity described by Power Law and Herschel-Bulkley models (R2 > 0.96). Scoby-formulated jams had higher carbohydrates (up to 23.2 g/100g), total dietary fiber (up to 0.4 g/100g), protein (up to 0.3 g/100g) and lower fat (<0.1 g/100g) compared to commercial jam and received >70% for overall acceptability in the hedonic test. Microbiome analysis via Next-Generation Sequencing identified Komagataeibacter and Zygosaccharomyces as characteristic microorganisms of all kombucha and jams. The attempt to use scoby in jam formulation in this research for enhancing kombucha fermentation is novel. Both kombucha and scoby-formulated jams are clean-label foods with probiotic and bioactive functionality based on advanced microbial analysis.

Text FK 2024 18 - Full Text.pdf Available under License Creative Commons Attribution Non-commercial No Derivatives. Download (3MB) Text FK 2024 18.pdf Restricted to Repository staff only Available under License Creative Commons Attribution Non-commercial No Derivatives. Download (3MB) Official URL or Download Paper: http://ethesis.upm.edu.my/id/eprint/18982

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