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Cocoa husks were used as the source for the pectin extraction by sugar acid treatment. A full factorial design was applied to screen the independent variables influencing the yield and uronic acid content. Followed by response surface methodology (RSM) was conducted using central composite design to optimize the extraction conditions. The optimized extraction condition was denoted as pH 2.5/95 °C/45 min. The yield and the uronic acid content of the extracted pectin was determined as 4.2 ± 0.12% and 74.5 ± 0.3% respectively. The extracted pectin was proved to be low methoxy pectin (LM pectin) with an 8.1% degree of esterification (DE). The pectin solutions showed shear thinning behaviour which was explicated by Williamson model. This work promotes environmentally friendly technology for pectin isolation., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Different extraction conditions were applied to investigate the effect of temperature, extraction time and substrate-extractant ratio on pectin extraction from cocoa husks. Pectin was extracted from cocoa husks using water, citric acid at pH 2.5 or 4.0, or hydrochloric acid at pH 2.5 or 4.0. Temperature, extraction time and substrate-extractant ratio affected the yields, uronic acid contents, degrees of methylation (DM) and degrees of acetylation (DA) of the extracted pectins using the five extractants differently. The yields and uronic acid contents of the extracted pectins ranged from 3.38-7.62% to 31.19-65.20%, respectively. The DM and DA of the extracted pectins ranged from 7.17-57.86% to 1.01-3.48%, respectively. The highest yield of pectin (7.62%) was obtained using citric acid at pH 2.5 [1:25 (w/v)] at 95 °C for 3.0 h. The highest uronic acid content (65.20%) in the pectin was obtained using water [1:25 (w/v)] at 95 °C for 3.0 h., (Copyright © 2013 Elsevier Ltd. All rights reserved.)