Optimization of oil and pectin extraction from orange (Citrus sinensis) peels: a response surface approach

The effects of processing parameters on essential oil and pectin extractions from orange peels were investigated using response surface approach; 2 x 5 and 3 x 5 central composite rotatable designs were adopted for the essential oil and pectin extractions, respectively. Extraction temperatures (80-100 degrees C) and extraction times (120-240 min) were chosen for essential oil extraction, while extraction temperatures (80-100 min), extraction times (60-120 min), and extraction pH (1.0-3.0) were chosen for pectin extraction. Essential oil yield ranged from 0.57-3.24%, while pectin yield ranged from 12.93-29.05%. The predicted optimum value for essential oil yield was 3.38% at extraction temperature of 95.23 degrees C and extraction time of 231.30 min, while the predicted optimum value for pectin yield was 30.00% at extraction temperature of 93.07 degrees C, extraction time of 117.00 min, and extraction pH of 1.60. Deviations between experimental and predicted values were low and statistically insignificant. All processing factors have significant effects on both extractions. The physicochemical properties of the essential oil and pectin extracted at the optimum conditions fell within tolerable and acceptable range.