Oil and pectin extraction from citrus paradise(grape) peels: A case of response surface optimization

This work reflects the extraction process of oil and pectin from grape peels using a response surface method in which a central composite rotatable design of 25 and 35 was used for the two extractions. Output temperatures (80–100°C) and heating times (5–9 hours) were used for oil extraction, while (80 -100oC) and heating times (20 – 60 minutes) and a pH of extract (1.0 – 3.0) were selected for pectin removal. Oil yield ranged from 7.90 - 15.30%, while pectin yield ranged from 19.90 – 35.70%. A maximum oil yield of 15.30% was obtained at a temperature of 90oC at a heating time of 9.0 hours, while a maximum yield of pectin of 35.70% was obtained at a pH of 2.5, 95oC temperature and 50 minutes heating time. The optimum value for oil production was 15.63% at an average temperature of 99.64oC and heating time of 8.99 hours, while the average value of pectin yield was 38.01% at an output temperature of 94.00oC, the period release time of 58.00 minutes with a pH of 2.00. The deviation between the experimental and predicted values was low and not significant. All processing conditions have important impacts on the extraction of oil and pectin from grape peels.