Extraction and Characterization of Pectin from Orange (Citrus sinensis), Lemon (Citrus limon) and Tangerine (Citrus tangerina)

Purpose: The study focused on the extraction and characterization of pectin from orange (Citrus sinensis), lemon (Citrus limon), and tangerine (Citrus tangerina) Methodology: Pectin was extracted from lemon (Citrus limon), tangerine (Citrus tangerina) and orange (Citrus sinensis) peels. The feasibility of the citrus peel pectin for use in food processing was assessed. Pectin from these citrus fruit peels was extracted under the same extraction conditions. The pectin extraction was carried out using hydrochloric acid (0.05N, pH 2.22; 0.04N, pH 1.54 and 0.03N, pH 1.27). Findings: Pectin from the acidified fruit peels was extracted at 70 ± 0.5°C for 1 hour at the different pH values. The highest pectin yield from all fruit peels was obtained at pH of 1.27, with lemons having the highest yield followed by oranges and lastly tangerine in the order; 16.61%, 16.01% and 15.23% respectively. Second highest yield was obtained at pH 1.54 in the same order; lemon (15.65%), orange (15.23%) and tangerine (13.87%). The least yield was obtained at a pH of 2.22; lemon (10.52%), oranges (11.01%) and tangerine (9.45%). The average yield was highest in lemon, orange and lastly in tangerine with percentages of 14.36%, 14.08% and 12.82% respectively. Chemical characterization of the citrus peel pectin revealed that the equivalent weight of pectin from all samples was generally low as compared to that of commercial pectin. The average equivalent weight in mg/mL was found to be 150.43, 116.78 and 97.15% for lemon, orange and tangerine respectively. Methoxyl content showed that the pectin obtained for all the samples was high (HM); lemon (11.49%), orange (14.94%) and tangerine (12.02%). Anhydrouronic acid (AUA) values were lemon (76.92%), orange (100.03%) and tangerine (86.38%) which are above the minimum of 65% set by FAO, while the degree of esterification (DE) was high for all; lemon (84.54%), orange (84.68%) and tangerine (78.88%) indicating that all were rapid-setting pectin. The colors of pectin obtained from lemon and orange were pale yellow while that obtained from tangerine was brown. Unique contribution to theory, practice, and policy: Depending on the AUA, lemon pectin was the purest of all the three samples, followed by tangerine and lastly orange peels. For commercial use of this pectin, lemon pectin is most suitable then tangerine and lastly orange basing on the methoxyl content. It is recommended that for better yields, pectin should be extracted on a dry basis instead of a wet basis.