Effect of Vacuum-Membrane Filtering on Quality Attributes and Extraction Efficiency of Pectin from Citrus Peel

Pectin, which is made from citrus peel and waste, is one of the most commonly used compounds in the food industry. For large scale production, a combination of membrane-vacuum filtering has been suggested as an alternative to traditional methods of purifying the acidic solution for pectin extraction. This study investigates the main factors regarding membrane filtering system for separation of fibrous materials from an acidic pectin solution under vacuum. These factors which include: filter-aid-particle size, amount of filter-aid (perlite) added to the solution, and the vacuum level, affect production efficiency, degree of esterification, and galacturonic acid content. Pectin extraction efficiency is an important criterion for evaluating the filtration system and test results showed that both perlite particle size and perlite-layer thickness significantly affect this dependent variable. By increasing the perlite particle size from 20 to 100 microns, the extraction efficiency has doubled. This is while increasing the perlite layer thickness from 1 cm to 2 cm cuts the efficiency in half (from 20% to 10%). The highest galacturonic acid content was obtained with 2cm perlite thickness and 20-microns particle diameter. The degree of esterification was affected by the extraction conditions, and results revealed that the extracted pectin samples have an esterification degree of 70±5%. The optimum extraction conditions were determined by the software to be: 2 cm perlite-layer thickness and 56-microns filter-aid particle size at a vacuum level of 0.38 bars. Findings of this study can be utilized in the industrial scale implementation of a biomaterial separation system using vacuum-membrane filtering.