Extraction, Characterization, and Antioxidant Activity of Pectin from Lemon Peels.

Pectin is a natural polymer that is found in the cell walls of higher plants. This study presents a comprehensive analysis of pectin extracted from lemon in two different geographic regions (Peddie and Fort Beaufort) in two consecutive years (2023 and 2024) named PP 2023, PP 2024, FBP 2023, and FBP 2024. The dried lemon peels were ground into a powder, sifted to obtain particles of 500 µm, and then subjected to pectin extraction using a conventional method involving mixing lemon peel powder with distilled water, adjusting the pH level to 2.0 with HCl, heating the mixture at 70 °C for 45 min, filtering the acidic extract, and precipitating pectin with ethanol. The yield of these pectin samples was statistically significant, as FBP 2024 had a maximum yield of 12.2 ± 0.02%, PP 2024 had a maximum yield of 13.0 ± 0.02%, FBP 2023 had a maximum yield of 12.2 ± 0.03%, and PP 2023 had a maximum yield of 13.1 ± 0.03%, The variation in yield could be due to the differences in the growing conditions, such as the climate and soil, which could have affected the pectin content in the lemons. The physicochemical characterization of all samples proved that our pectin samples could be used in the pharmaceutical and food industries, with anhydrouronic acid content which was greater than 65%, as suggested by the FAO. The scanning electron microscope analysis of all extracted pectin was rough and jagged, while the commercial pectin displayed a smooth surface morphology with a consistent size. FTIR confirmed the functional groups which were present in our samples. Thermogravimetric analysis was employed to investigate the thermal behavior of the extracted pectin in comparison with commercial pectin. It was found that the extracted pectin had three-step degradation while the commercial pectin had four-step degradation. Additionally, pectin samples have been shown to have antioxidants, as the IC50 of PP 2024, PP 2023, FBP 2023, FBP 2024, and Commercial P was 1062.5 ± 20.0, 1201.3 ± 22.0, 1304.6 ± 19.0, 1382.6 ± 29.9, and 1019.4 ± 17.1 mg/L, respectively. These findings indicate that lemon pectin has promising characteristics as a biopolymer for use in biomedical applications.

Citrus limon Wastes from Part of the Eastern Cape Province in South Africa: Medicinal, Sustainable Agricultural, and Bio-Resource Potential.

The fruits of Citrus limon are often purchased for their vitamin C-rich juice, while the fruit peel and the tree leaves are discarded as wastes. This study obtained the chemical profiles of the essential oils (EOs) of C. limon wastes (the peel and leaves), evaluated their medicinal value as antioxidants, their potential for sustainable use in agriculture as an insecticide for post-harvest preservation of grains, and their potential as a bioresource in livestock feed formulations. The EOs were isolated from C. limon leaves and peel using a hydro-distillation method on a Clevenger apparatus. The oil constituents were identified using the gas chromatography-mass spectrometry (GC-MS) hyphenated technique. The oils were evaluated for their in vitro antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric-reducing antioxidant power methods. An insecticidal study was conducted using contact toxicity, fumigation, and repellence bioassay methods against Sitophilus zeamais (maize weevils). Finally, the predicted income from using lemon peel as an alternative or substitute ingredient for maize in livestock feed formulations was obtained through a conventional simulation method. Chemically, limonene was found to be present in all the EOs analyzed (12-52%), while α-pinene was only found in the fresh leaf and peel oils (13.3% and 10.6%). Caryophyllene oxide was identified as the major component of the dried leaf oil (17.7%). At 20 µg m, the dry peel oil exhibited the highest inhibitory activity (52.41 ± 0.26%) against the DPPH radical, which was comparable to L-ascorbic acid (a standard antioxidant) at 54.25 ± 3.55%. The insecticidal study revealed that the dry peel oil is a better insect repellent (73.33 ± 6.95% at 10 µL) and fumigant (LC50 = 0.17 µL g-1 after 48 h) natural agent compared to the peel oil. Conversely, the dry peel oil showed a better contact activity (LC50 = 1.69 µL g-1) against the maize weevils compared to the dry leaf oil. The simulation study showed the cost of using dry lemon peel as an alternative to maize in livestock feed formulation to be ZAR 2.8 billion, compared against the higher cost of feed formulation with maize, which currently stands at ZAR 24.9 billion. This study has shown that C. limon wastes (the peel and leaves) contain EOs with unique chemical profiles, valuable medicinal properties as free radical scavengers, and considerable insecticidal properties for agricultural use in post-harvest grain preservation, presenting a cost-effective and promising bioresource for livestock feed production.