The Potency of Green Tea Powder in Enhancing the Antioxidant Activity and Sensory Properties of Pluchea-Butterfly Pea Flower Herbal Tea

Pluchea herbal tea, derived from pluchea leaf powder infusion, exhibits an unappealing colour and low antioxidant activity. A previous study combining pluchea leaf powder with butterfly pea flower powder in a 40:60% w/w ratio improved sensory preference but failed to significantly enhance bioactive constituents and antioxidant activity. Given the well-documented antioxidant properties of green tea, this study aimed to investigate the effects of incorporating green tea on the antioxidant activity, bioactive constituents, and sensory properties of herbal tea composed of green tea-pluchea leaf and butterfly pea flower powders in a 40:60% w/w ratio. A randomized block design was employed with a single factor: the proportion of green tea powder to pluchea leaf powder (0:100, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, 90:10, and 100:0% w/w) in four replicates. Among these formulations, the 80:20% ratio of green tea to pluchea leaf powder demonstrated the most significant improvement in DPPH free radical scavenging activity with value of 981±12 mg GAE/kg, bioactive compounds content, with total phenol content of 37,469±413 mg GAE/kg and total flavonoid content of 3406±29 mg CE/kg. The panelist preference of colour parameter was also improved, but ferric reducing antioxidant power and other sensory properties, such as aroma and taste were not significantly different compared with the control (pluchea leaf powder with butterfly pea flower powder in 40:60% ratio). These results indicate that the formulation of green tea, pluchea leaf, and butterfly pea flower powders at 28:12:60% w/w ratio have strong potential for development as a functional herbal beverage.