Physicochemical, Rheological, and Functional Properties of Quince Peel Pectin Extracted via Conventional and Microwave-Assisted Citric Acid Methods

• Amina Mohsen Same1 and Basmaa Saaduldeen Sheet 2

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This study compared conventional acid extraction and microwave-assisted acid extraction in terms of their effects on the physicochemical, rheological, and functional properties of pectin recovered from quince peels. Quince peel powder was extracted using 0.1 M citric acid at pH 2. Conventional extraction was conducted at 85°C for 60 min, whereas microwave-assisted extraction was performed at 600 W for 4 min. The recovered pectin was precipitated with ethanol, freeze-dried, and compared with standard high- and low-methoxyl pectins. Moisture content, solubility, free carboxyl groups, pH, viscosity, gel strength, cohesiveness, elasticity, and purity were evaluated. The moisture contents of acid- and microwave-extracted pectins were 10.34 and 10.36%, respectively, with no significant difference between them. Microwave-extracted pectin showed the highest solubility at 91.00%, which was comparable to that of standard high-methoxyl pectin at 90.73% and higher than that of acid-extracted pectin at 85.01%. The viscosity values ranged from 4.36 to 10.65 mPa·s, with microwave-extracted pectin recording 10.64 mPa·s, close to the value of standard high-methoxyl pectin. Microwave-extracted pectin also exhibited greater gel strength than acid-extracted pectin, reaching 283.60 and 257.00 g, respectively. No significant differences were observed in cohesiveness among the samples. Pectin purity was 88.25% for microwave-assisted extraction and 88.08% for conventional acid extraction. HPLC analysis confirmed the presence of galacturonic acid, with microwave-extracted pectin showing the same retention time as the standard compound. These findings indicate that microwave-assisted acid extraction can substantially reduce extraction time while producing quince peel pectin with favorable solubility, viscosity, gel strength, and purity.

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