Pectin from different fractions of dragon fruit (Hylocereus polyrhizus) peel was extracted using 1% citric
acid and the physico-chemical characteristics of the pectin were studied. The highest pectin yield (26.38%
on dry weight basis) was obtained from fresh inner layer of the peel when extraction was carried out at
temperature: 73 C, time: 67 min, pH: 2.03, and sample to citric acid ratio: 1:4 (w/v). The pectin also
demonstrated the highest degree of esterification (63.74%) when compared with pectin from other
fractions of the dragon fruit peel investigated in this study. The calculated degree of esterification
confirmed that the extracted pectin is a high methoxyl pectin. The molecular weight of the pectin
determined using size exclusion chromatography was 0.88 105 Da. Monosaccharide composition
determined using high performance liquid chromatography revealed that the pectin was predominantly
constituted of galacturonic acid (39.11%), followed by moderate concentrations of mannose, rhamnose,
galactose, glucose and minor amounts of xylose and arabinose. The pectin exhibited Newtonian
behaviour at concentrations of 0.5% and 1.0%, and pseudoplastic behaviour at concentrations of 2.0% and
3.0%. Although the viscosity of the dragon fruit peel pectin was lower than that of commercial apple and
citrus pectins, it can be used as a functional and health ingredient in low viscous foods and beverages.
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