Evaluation of physicochemical and antioxidant activity of Rosa Damascena and Osmanthus Fragrans infused rambutan vinegar

The antioxidant benefits of Rambutan (Nephelium lappaceum) vinegar are not widely known and also the vinegar in the market shows unappealing physical properties such as its colour and smell, resultantly, fails to attract consumers' attention. Dried edible flower such as Rose (Rosa damascena) and Osmanthus (Osmanthus fragrans) infused vinegar have yet to be released in the Malaysian market and its benefits is not widely known. DPPH assay was used to determine the antioxidant activity, Folin-Ciocalteua's method was used to determine total phenolic content, aluminium chloride colorimetric method was used to determine total flavonoid content and AOAC pH differential method was used to measure anthocyanin pigment of flower infused Rambutan Vinegar (RV). The physicochemical properties such as the colour analysis, pH, total soluble solid (TSS), acetic acid content and antioxidant activity of Rose infused Rambutan Vinegar (RVR) and Osmanthus infused Rambutan Vinegar (RVO) show differences when compared to RV. Antioxidant activity of RVR and RVO shows significance increase compared to RV. The antioxidant activity of RV(3 g Rose) at Week 2 (68.37%) is higher than RV(1 g Osmanthus) at Week 2 (29.92%). The total phenolic content, total flavonoid content and anthocyanin pigment of RVR and RVO shows significant increase compared to RV. RV(3 g Rose) at Week 2 shows the highest total phenolic content (152.29 GAE lig/mL) and highest anthocyanin pigment (1.89 C3G mg/L) whereas RV(1 g Osmanthus) at Week 2 shows the highest total flavonoid content (1.79 QE mg/mL). To summarise, the best concentration of edible flowers infused in RV and time of infusion for RVR is RV(3 g Rose) at Week 2 and RVO is (RV(1 g Osmanthus) at Week 2. Keywords: infused vinegar, colour, physicochemical properties, antioxidant properties