The effect of adding Garcinia atroviridis on pH, colour and antioxidantproperties of roselle tisane

Roselle (Hibiscus sabdariffa) is rich in antioxidants and phenolic compounds, especially anthocyanins, which have shown therapeutic potential. The anthocyanin content in roselle tisane would increase in an acidic solution, thus enhancing its antioxidant properties and colour intensity. This study was carried out to investigate the influence of adding different ratios of Garcinia atroviridis on the pH, colour, anthocyanin content, and antioxidant properties of roselle tisane. The ratio of roselle: Garcinia atroviridis (GA) (w/w) studied was 2:0, 2:1, 2:2 and 2:3. The results showed that the pH was decreased as the amount of GA increased, hence increasing 25% of the anthocyanins content of roselle tisane. Furthermore, the colour of the tisane with GA became bolder and more saturated, as indicated by the increase in colour values (L*, a*, b*, chroma, and hue angle) with higher levels of GA. Results of antioxidant properties (total polyphenol, total flavonoid and ferric reducing antioxidant power assay) also showed an increment as the amount of GA increased. Conversely, the DPPH assay demonstrated a 17% decrease in the percentage of inhibition as the amount of GA increased. Roselle tisane infused with GA displayed weakened radical scavenging abilities, as indicated by higher IC50 values. However, all samples exhibited effective antioxidant activity, with IC50 values below 1 mg/mL. In conclusion, adding GA to the formulation could affect the properties of roselle tisane. The higher content of GA in the formulation significantly increased the anthocyanin content and antioxidant activities of the roselle tisane.