Semi-Pilot scale extraction of pectin from orange peel waste and evaluating its quantitative and qualitative features

Pectin as a natural polysaccharide possesses a wide spectrum of functional properties. It can act as a thickener, gelling agent, stabilizer, emulsifier, cation-binding agent, etc. These properties make pectin as a biopolymer valuable especially for medicine and food production. All of the pectin needed in food, medicine and cosmetic industries is supplied abroad while there is a good potential for production of this valuable substance from waste of beverage industries. In addition, the production of the pectin is simple and low cost and its added value is high. Pectin production was done only in laboratory scale and has not been industrialized. Therefore, the aim of this research was to optimize the pectin extraction from orange juice waste in the laboratory scale and then, scaling up to semi- pilot extraction. Designing and constructing the production line of Semi-pilot scale extraction of pectin from orange peel was done for the first time in Iran, to can finally, evaluate the possibility of industrialization and localization of the pectin.

In the first, the effect of pH (1.5-3), time of extraction (1-4 h) and S/L ratio (1:10- 1:30 g/mL) were optimized singularly and then, semi-pilot production of pectin at the optimized condition, which was obtained at the laboratory scale, was done. Two filtration methods (filter press and centrifuge) were used to to separate impurities. The yield, DE and galacturonic acid content of the extracted pectins in the semi- pilot scale were compared to the laboratory one.

The results indicated that all the parameters had significant effect (p≤0.05) on the yield of the extracted pectin. Increasing the pH from 1.5 to 2 increased the yield and the highest yield was obtained at pH of 2 (14.87 g/100 g d.m.) and by increasing pH from 2 to 3, the yield was decreased (6.65 g/100 g d.m). Increasing the time of extraction up to 3 h, enhaned the yield significantly but then, it was remain constant. By increasing the S/L ratio from 1:10 to 1:15, the yield was increased from 16.55 to 18.84 g/100 g d.m. and after that the yield was decreased. Designing the pectin production line was done and semi- pilot extraction was done at the optimized conditions (pH of 2, S/L ratio of 1:15 and time of 3 h). The yield of extracted pectin in the semi- pilot scale (which filter press employed instead of centrifuge) was more than that obtained at the laboratory scale althogh its galacturonic acid content was lower than that obtained at semi- pilot scale. When centrifuge was employed, the extracted pectin at the semi- pilot scale was comparable with laboratory one, indicating its high purity.

Results indicated that the yield and quality properties of the pectin extracted at the semi-pilot extraction, which centrifuge was employed (instead of filter press), were similar to the pectin extracted at the laboratory scale and therefore, producting the pectin with high yield and quality at the semi-pilot scale is possible.