Optimization of processing parameters for the preparation of clove (Syzygium aromaticum) hydroalcoholic extract: A response surface methodology approach to characterize the biofunctional performance

Clove is one of the most popular aromatic and medicinal plants used due to its strong bioactivity. Hydroalcoholic extract of the plants also named as tincture is a popular pharmaceutical form of the medicinal plants. The current study aims to determine the optimum production conditions of clove tincture in terms of the processing variables. For this purpose, response surface methodology was applied and liquid/solid ratio (X-1) and ethanol concentration (X-2) were selected as processing variables. As response, some antioxidant and antiradical capacity tests were conducted in addition to the concentration of photochemical constituents. Analysis of variance (ANOVA) showed that the both variables had a significant influence on both antioxidant and antiradical activities of the samples. Total phenolic and flavonoid contents of the tincture samples were in the range of 13.81-23.84 mg GAE/mL and 3.64-7.83 mg QE/mL, respectively while the ABTS(center dot+) radical scavenging activity and ferric reducing antioxidant activity (FRAA) values ranged from 44.78 to 174.70 mu g Trolox/g sample and 62.77 to 87.71 mg AAE/L, respectively. Multiple response optimization indicated that the optimum values for the production of tincture were obtained for X-1 = 4.03 mL/g sample and X-2 = 53.2 % ethanol concentration. Our results indicated that the clove tincture having high antioxidant and antiradical performance could be produced at optimized conditions determined by response surface methodology.