University of Khartoum

Characterization of Pectic Substances Extracted From Orange (Citrus Sinensis) Peels

Characterization of Pectic Substances Extracted From Orange (Citrus Sinensis) Peels

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Title: Characterization of Pectic Substances Extracted From Orange (Citrus Sinensis) Peels
Author: Mohamed, Wisal El Musafa Elsiddig
Abstract: Pectic substance of two types of orange peels (yellow and green) were investigated. Samples were obtained from the local market. The orange fruits were washed, peeled and then the peels dried and ground. The study involved chemical composition, alcohol insoluble solids of orange peels and isolation of orange peels pectic substances, which were assayed and characterized for their moisture, ash, alkalinity, protein, acetyl content, methoxyl content, total carboxyl groups, anhydrogalacturonic acid, equivalent weight, calcium, magnesium, degree of esterification, intrinsic viscosity and molecular weight. Results showed that yellow and green orange peels contained 6.72% and 7.92% moisture, 2.90% and1.85% ash, 5.84%and 6.65% protein, 8.30% and 9.47% fibre, 3.08% and 2.75% oil, 0.43% and 0.40% titrable acidity, 60.09mg/100gm and 34.95mg/100gm ascorbic acid, 11.01% and 5.03% reducing sugar, 16.62% and 7.77% total sugars, 0.78mg/100g and 0.83mg/100gm calcium, 0.19mg/100g and 0.18mg/100gm magnesium and 50.55% and 60.74% alcohol insoluble solids respectively. The results showed that alcohol insoluble solids of the two types contained 2.92% and 5.63% moisture, 4.09% and 4.48% ash, 7.65% and 7.49% protein, 14.84% and 16.06% pectin, 0.22mg/100gm and 0.21mg/100gm calcium and 0.12mg/100gm and 0.11mg/100mg magnesium respectively. The results obtained, indicated that green orange peels contain relatively higher percentage of pectin compared to yellow orange peels. Total pectin was found to be 14.48% for yellow type and 16.06% for green type. The methoxyl content was 8.95% and 8.87% respectively. The acetyl content was found to be 0.44%, for yellow peels and 0.46% for green type. The degree of esterification was estimated to be 73.8% for yellow type and 72.47% for green type. The total carboxyl groups were found to be 1.96meq/gm for yellow type and 1.98meq/gm for green type. The anhydrogalacturonic acid content was 68.99% and 69.49%, respectively. The equivalent weight was estimated to be 974.60 and 920.73 respectively. The viscosity was 2.2/g/dl and 2.07g/dl respectively. The molecular weight was estimated to be 4.2 × 104 for yellow type and 4.03 × 104 for green type. The ash content was 3.14% and 3.37% respectively. The protein content was 3.57% and 3.44% respectively. The calcium content was found to be 0.28mg/100gm for yellow type and 0.3mg/100gm for green type. The magnesium content was estimated to be 0.09mg/100gm and 0.07mg/100gm, respectively. The results, obtained in this study, indicated that both quantity and quality of pectin obtained from orange peels (yellow and green) are suitable for the commercial production of pectins.
Description: Jun 2005
URI: http://khartoumspace.uofk.edu/handle/123456789/11062
Date: 2015-05-19


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