Multivariate optimization of ultrasound-assisted extraction rich polyphenol from robusta coffee fruit peel ( Coffea canephora) using factorial design

Robusta coffee fruit peel contains many polyphenolic compounds, so the antioxidant activity is high. These compounds require special extraction techniques to obtain optimal results. This study aims to determine the optimal extraction process conditions for producing polyphenol compounds (flavonoids and anthocyanins) with strong antioxidant activity. The robusta fruit peel extraction process uses the ultrasound- assisted extraction (UAE) method and is analyzed using the full factorial design (FFD) application. Factors in determining the optimal extract consist of extraction time (10-45 minutes), extraction temperature (25-50 degrees C), and solvent pH (2-5). The observed responses included percent yield, total flavonoids, anthocyanin levels, and antioxidant activity. The results of the extraction optimization yielded the optimal extract at an extraction time of 45 minutes, an extraction temperature of 50 degrees C, and a pH of 2. The optimum extract has a yield value of 17.25%, TFC 242.26 mgCE/g, anthocyanins 367.04 mg/100 g, and IC50 22.11 mu g/mL. Extract optimization results show a good value with desirability of 0.997. The optimum extract contains 0.21% water content and 0.26% dry shrinkage. The optimum results of the phytochemical screening of the extract contained phenolic compounds, flavonoids, tannins, saponins, and alkaloids. The optimum extract verification results obtained yield percent values of 17.10%, TFC 250.28 mgCE/g, anthocyanins 391.20 mg/100 g, and antioxidant activity 24.54 mu g/mL. The response results show values supporting verification, as evidenced by 95% CI and 95% TI range values.