| Summary: | Pectin was extracted from unshiu orange (Citrus unshiu) peels and was subjected to chemical modification using hydroxamic acid. The structural and physical properties of the resulting derivatives were investigated as a function of hydroxamic acid content (4.68-9.58%). The extracted unshiu orange pectin showed 66.8% degree of esterification, 787.5 mg/g galacturonic acid, and 92 mg/g neutral sugars, which were composed of arabinose (53%), galactose (35%), glucose (5%), rhamnose (5%), and fructose (2%). Compared to the native
pectin, the FT-IR spectra of the hydroxamic acid derivatives showed two new absorption bands at 1,646 cm-1 (C=O) and 1,568 cm-1 (N-H). Specifically, the pectin derivatives with more hydroxamic acids were shown to have enhanced water solubility, upto two-fold higher than that of the native pectin. Thus, the introduction of hydroxamic acid into the pectin structure appears to be a useful tool for improving the solubility of pectin.
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