Extraction and characterization of high methoxyl pectin from Citrus maxima peels using different organic acids

The objective of this study was to determine the effects of citric acid, acetic acid and lactic acid on extraction yield, chemical structure and antioxidant capacities of high methoxyl pectins extracted from peels of different pomelo varieties. The pectins were extracted by mixing freeze-dried pomelo peels with organic acids (pH 3.0) at a ratio of 1:30 (w/v). The results indicate that extraction yields of pectin extracted using citric acid was the highest (6.5-9.0%), followed by that using acetic acid (6.2-8.2%) and lactic acid (6.1-8.0%). All extracted pectins were categorized as high methoxyl pectins with degrees of esterification of 51.1-62.7%. Galacturonic acid content of the extracted pectin using citric acid (76.5-85.0%) was significantly higher than that using acetic acid (65.1-68.2%) and lactic acid (60.4-65.8%). The antioxidant capacity of the pectins using citric acid and lactic acid was significantly higher than that using acetic acid. FT-IR results show that structures of the extracted pectins from peels of different pomelo varieties were different. As a result, the pure high methoxyl pectin could be produced from pomelo peel by-products under organic solvent extraction, a potential green extraction technique.

Automated summary

This study investigated the effects of citric acid, acetic acid, and lactic acid on the extraction of high methoxyl pectins from different pomelo peels. Results showed that citric acid extraction yielded the highest pectin content and antioxidant capacity.