Effects of Rose-water on the Total Phenol and Flavonoid Content and Radical Scavenger Activity in Fermented Broth with Komagataeibacter xylinus

Abstract

Komagataeibacter xylinus is a cellulose-producing bacteria. This bacteria is known to be symbiotic with yeast associated with yeast and kombucha production. Several herbs and spices are commonly added during the fermentation process to enhance the flavour of kombucha. Nevertheless, the efficiency of rose water on the quality of kombucha remains limited.  Therefore, the current study aims to determine the effect of rose water derived from petals of Bishop’s Castle species on the total phenolic, flavonoid and radical scavenging activity of the broth rose. The K. xylinus was inoculated to various concentrations of rose water (0 to 100% v/v) and analysed for the chemical compound and scavenging activity after fermentation for 15 days. The results showed that bacterial growth, total phenolic and flavonoid content, as well as radical scavenging activity decreased with the concentrations of rose water applied in the culture medium. The highest total phenol (0.07 mg/ml) and flavonoid (0.07 mg/ml) content was obtained from broth containing 20 % (v/v) rose water. The radical scavenging activity was comparable to the control medium in treatment containing lower concentrations (20 to 60 % v/v) of rose water. In conclusion, biologically active chemicals in the rose water might inhibit the growth of bacteria and contribute to the total content of analysed secondary metabolites in the broth. Further study should be carried out to determine the effects of lower concentrations and a variety of rose water applied after the bacteria attained the growth phase.