Optimising the Nutritional Value of Kombucha Using Fruit Peels as Functional Ingredients

Kombucha, a popular fermented beverage made from tea leaves, has not been extensively studied in terms of the incorporation of fruit peels that are often wasted.This research aims to produce and optimise a kombucha beverage by utilising fruit peels, specifically dried orange (Citrus reticulata) peels infusions formulated with dried pomegranate (Punica granatum L.) peels, as functional food ingredients.Eight kombucha formulations infused with orange peel (OP) and pomegranate peel (PP) were obtained from a simplex lattice mixture design (Design Expert 13.0.1 software).The optimisation parameters for formulating the kombucha were total phenolic content (TPC), antioxidant activity using DPPH radical scavenging activity assay, and antimicrobial activity against Staphylococcus aureus and Escherichia coli using well diffusion assay.An optimal formulation of kombucha incorporated with OP and PP was obtained and the results demonstrated that the optimised formulation consisted of 32.40% OP and 67.60% PP, achieving a desirability value of 0.505.This combination of OP and PP improved the TPC, antioxidant activity and antimicrobial activity of the optimised kombucha.This study presents an optimised formulation and highlights the potential of incorporating fruit peels to enhance the nutritional value of kombucha with new flavours.The newly formulated kombucha may offer new variations of kombucha flavour compared to commercialised products in future studies.