Isolation, characterization of pectin from citrus lemon waste and their biological potential

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dc.contributor.advisorOyedeji, O.
dc.contributor.authorDambuza, Anathi
dc.date.accessioned2026-09-07T12:41:28Z
dc.date.available2026-09-07T12:41:28Z
dc.date.issued2024
dc.descriptionMasters dissertation
dc.description.abstractThis research offers an in-depth examination of pectin derived from lemon peels. The lemon peels were sourced from two distinct geographical areas (Peddie and Fort Beaufort) over two successive years (2023 and 2024), referred to as PP 2023, PP 2024, FBP 2023, and FBP 2024. Authentication and verification of the plant were done, and the voucher specimen was obtained. The voucher specimen numbers for both Fort Beaufort and Peddie lemon samples were UFH-2023-06-01 and UFH-2023-06-02 respectively. The extraction process involved drying the lemon peels, grinding them into powder, sifting to obtain 500 µm particles, and subjecting them to a conventional extraction method using 2M HCl. The yields of the pectin samples were found to be statistically significant (p<0.05), with PP 2023 at 13.1 ± 0.03%, PP 2024 reaching 13.0 ± 0.02%, FBP 2023 at 12.2 ± 0.03%, and FBP 2024 achieving a maximum yield of 12.2 ± 0.02%. The slight differences in yield may be attributed to variations in growing conditions, including factors such as climate and soil, which could have influenced the pectin content in the lemons. Physicochemical characterizations showed that all samples had anhydrouronic acid content greater than 65%, making them suitable for pharmaceutical and food industry applications, as suggested by the FAO. SEM analysis revealed rough, jagged morphologies for the extracted pectin, contrasting with the smoother surface and consistent size of commercial pectin. The EDX analysis showed that Commercial pectin had 36.54 % carbon and 56·02 % oxygen levels typical of pectin makeup, in contrast, FBP 2023 and FBP 2024 had oxygen levels at 62.11 % and 63·92 % respectively signifying differences in their structural composition. PP 2023 had a carbon level (41.45%), with some chlorine originating from HCl used during the extraction process, whereas PP 2024 had similar high oxygen content but a lower percentage of carbon indicating a form of pectin that is relatively pure. FTIR confirmed the presence of characteristic functional groups such as Hydroxyl Groups (–OH), Carboxyl Groups (C=O) and β-Glycosidic Linkages (C–O), and the Thermogravimetric analysis was utilized to examine the thermal properties of all four samples of the extracted pectin in relation to commercial pectin. The results indicated that the extracted pectin underwent three stages of degradation, whereas the commercial pectin exhibited four stages of degradation. Additionally, differential scanning calorimetry (DSC) was employed to assess the thermal stability of the pectin samples. The DSC analysis showed that Commercial P possesses the highest heat resistance, among the samples tested by having a melting enthalpy of 400 J/g and a melting temperature of 94°C, on the other hand, FBP samples exhibited moderate stability. Chromameter analysis of colour, in pectin showed that Commercial P had a shade (brightness L*= 69.96) which suggests a preference for colours in food products, on the other hand, PP 2024 had a darker shade (brightness L*=61.03) possibly influenced by polyphenols content. Moreover, FBP 2023 exhibited a yellow hue (chromaticity C*=24.50) likely due, to carotenoids presence, in contrast, PP 2023 had lower chromaticity leading to a less attractive look. In ¹³C NMR spectra, peak at 32,38 ppm which was only on commercial pectin revealed aliphatic carbons, then at 52–70 ppm, 110–112 ppm, and around 170 ppm were attributed to methoxyl groups that are attached to the galacturonan, arabinose anomeric resonances, and C-6 of the carboxyl group of the galacturonic acid in esterified form, respectively. Consistency in these peaks suggests similar functionality. The 2,2-Dipheynl-1-picraylhydrazyl assay and reducing power assay were used to investigate the antioxidant activities of pectin samples, the DPPH assay demonstrated that pectin has antioxidants, as the IC50 of PP 2024 was 1062.5 ± 20.0 mg/L, PP 2023 was 1201.3 ± 22.0 mg/L, FBP 2023 was 1304.6 ± 19.0 mg/L, FBP 2024 was 1382.6 ± 29.9 mg/L and lastly, Commercial P had 1019.4 ± 17.1 mg/L. The reducing power of all pectin was later assessed, and they revealed their potential antioxidant properties. Ascorbic acid which was used as a standard antioxidant exhibited the highest reducing capacity as its absorbance at at 2500 mg/l was 1.75, followed by PP 2023 and PP 2024, while FBP 2023 showed the lowest capacity among the pectin samples, these results indicate that pectin possesses antioxidant properties, attributed to the presence of reductones that disrupt free radical chains and prevent peroxide formation. These findings provide valuable insights into the compositional, thermal, and functional properties of pectin, highlighting its potential as a natural polymer for use in food, pharmaceutical, and medical applications.
dc.identifier.citationDambuza, A. (2024) Isolation, characterization of pectin from Citrus lemon waste and their biological potential. MSc (Chemistry) dissertation. Alice, South Africa: University of Fort Hare.
dc.identifier.urihttp://hdl.handle.net/20.500.11837/5094
dc.language.isoen
dc.publisherUniversity of Fort Hare
dc.subjectPectin
dc.subjectAntioxidants
dc.subjectCitrus fruit industry -- By-products
dc.subjectLemon
dc.titleIsolation, characterization of pectin from citrus lemon waste and their biological potential
dc.typeThesis
person.identifier.orcid0000-0003-0698-2570

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