Valorization of orange peel as a source of pectin

Pectin is a natural structural polymer that is extensively used in food industry, medicinal and pharmaceutical fields. Considering their potential applications, in this work, microwave-assisted and conventional extraction were evaluated to extract pectin from orange peel by acid hydrolysis using citric acid as extractant. For conventional extraction, temperatures higher than 60°C and long extraction times were necessary to obtained pectin yields of 9.0%. Under convention conditions of extraction, the degree of esterification of pectin was 55.0%. The extraction procedure assisted by microwave was optimized using an experimental design of 3 factors and 2 levels, analyzing the effect of operational variables influence in the pectin yield. The optimization of pectin extraction condition showed that temperature of 55°C, extraction time of 6 min, and solid/liquid ratio of 0.02 mg/mL, are necessary to obtained pectin yields of 25.0%. Under the optimal extraction condition, the degree of esterification of pectin was about 75%. According to the ANOVA analysis, time was the factor that more influence had on yields of pectin. These results showed that microwave-assisted procedure allows obtaining pectin with suitable properties from orange peel over mild operation conditions.