Application of response surface methodology to extract yields from stinging nettle under supercritical ethanol conditions

• The response surface methodology (RSM) with a central composite design (CCD) was used for the optimization of stinging nettle extract yields.
• An R2 value of 0.94 represents fitness of the model.
• The most significant variable was found to be the extraction temperature.

Response surface methodology was employed using a central composite design of experiments to optimize experimental conditions for stinging nettle extract yields under supercritical ethanol conditions. The following independent variables were investigated: extraction temperature, extraction time and plant concentration. The most significant factor was found to be the extraction temperature. A correlation coefficient was estimated to be 0.94, which demonstrates the effectiveness of the model. The values of the parameters in optimized conditions for the stinging nettle extract yield included an extraction temperature of 335 °C, an extraction time of 87 min, and a plant concentration of 9.A subsequent validation experiment was carried out at the optimal conditions. The validation experiment showed that the actual and predicted values for the stinging nettle extract yields were 45.3 and 42.7 wt%, respectively. The stinging nettle extracts consisted of a collection of compounds including fatty acid esters (FAE), phenols, indoles, and nitrogen containing compounds.

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