An Optimization Study for The Production of Origanum onites Tincture by Response Surface Methodology: Effect of Solid/Liquid Ratio, Ethanol Concentration and Storage Period

In this study, Origanum onites was used for the production of tincture, a hydroalcholic extract, and manufacturing conditions were optimized to determine the processing factor variable levels to increase the final quality of samples. For this purpose, response surface methodology study was applied and Box Behnken design was used for the optimization. Three factors were selected namely liquid/solid ratio, ethanol concentration and storage period for the preparation of samples. Total phenolic content, antiradical activity and efficient of concentration (EC50) values were determined to evaluate the bioactivity of tincture samples. It was observed that the total phenolic content of the tincture samples was affected by ethanol concentration and liquid/solid ratio. Total phenolic contents of tincture samples were in the range of 964.1-7020.8 mg GAE/ L samples while the efficient concentration (EC50) ranged from 44.88 to 89.56. Increase of solid level increased the bioactivity values of samples, but this increment decreased the tincture yield significantly. Optimization results showed that the highest total phenolic content would be at 50% ethanol concentration, 6 ml ethanol level which means the liquid/solid ratio is 1:5 and 15 days storage for the tincture samples