Optimizing Procedures of Ultrasound-Assisted Extraction of Waste Orange Peels by Response Surface Methodology

The simultaneous effects of three continuous factors: solvent concentration (50-100%), treated times (25-85 min), treated temperatures (25-55 degrees C), and two categorical factors: type of solvents (methanol or ethanol) and ultrasonic frequency (28 kHz or 40 kHz) on ultrasonic-assisted extraction yield from waste orange peels were evaluated and optimized by response surface methodology. Fourier Transform Infrared (FTIR) spectroscopy with a wavelength of 500 cm(-1) to 4000 cm(-1) was employed to rapidly identify the orange extracts. The significant polynomial regression models on crude extraction, sediments after evaporation, and precipitation yield were established (p < 0.05). Results revealed that solvent concentration affected crude extraction and precipitation yield linearly (p < 0.01). The optimal and practical ultrasound-assisted extraction conditions for increasing the precipitation yield were using 61.42% methanol with 85 min at 55 degrees C under 40 kHz ultrasonic frequency. The spectra of extracts showed a similar fingerprint of hesperidin.

Automated summary

The effects of solvent concentration, treated times, treated temperatures, type of solvents, and ultrasonic frequency on the yield of ultrasonic-assisted extraction from waste orange peels were evaluated using response surface methodology. FTIR spectroscopy was used to rapidly identify the orange extracts. Polynomial regression models were established for crude extraction, sediments after evaporation, and precipitation yield. The results indicated that solvent concentration had a linear effect on crude extraction and precipitation yield. The optimal conditions for increasing precipitation yield were identified as 61.42% methanol concentration, 85 min treatment time, 55 degrees C temperature, and 40 kHz ultrasonic frequency.