Studies on Physicochemical Properties and Elemental Analysis of Citron and Pomelo Fruits Peels Pectins

This research work is aimed to study the physicochemical properties and elemental analysis of citron and pomelo fruits peels pectins which have been extracted. In the present work, determination of some physicochemical parameters such as color, moisture content, ash content, setting time, equivalent weight, methoxyl content, anhydrouronic acid (AUA), degree of esterification (DE), molecular weight and elemental analysis of the prepared pectins have been performed. The color of citron peel pectin and pomelo peels pectins were determined by eye test. Moisture contents were determined by oven drying method, ash contents were determined by the method used in the food analysis, setting times were determined by a simple method of Owens, equivalent weights, methoxyl contents, anhydrouronic acids (AUA) and degree of esterifications (DE) were determined by titrimetric method, molecular weights were determined by viscometric method and elemental analysis were determined by Energy Disperse X-ray Fluoresce (ED XRF) analysis. Physicochemical properties of the citron and pomelo peels pectins were found to be white-yellow and brown-yellow colors, 7.96% and 2.15 % of moisture contents, 1.07 % and 5.72 % of ash contents, 5 minutes and 12 minutes of  setting times, 2380 and 2500 of equivalent weights, 1.86 % and 2.29 % of methoxyl contents, 17.95 % and 20.06 % of anhydrouraonic acid contents and 58.83 % and 64.92 % of degree of estrifications and 6.61´ 104and 5.62 × 104 Da of molecular weights respectively. In the citron pectin, the relative abundance of Ca, K, Fe, Cu, Sr 20.06 % of anhydrouraonic acid contents and 58.83 % and 64.92 % of degree of estrifications and 6.61´ 104and 5.62 × 104 Da of molecular weights respectively. In the citron pectin, the relative abundance of Ca, K, Fe, Cu, Sr and Zn has been found to be 61.87 %, 22.67 %, 7.94 %, 3.11 %, 2.29 % and 2.13%, respectively (determined by ED XRF technique). Whereas in the pomelo pectin, the relative abundance of Ca, K, Fe, Cu, Sr and Zn has been found to be 66.32 % 11.82 %, 11.73 %, 2.75 %, 2.32 % and 5.06 %, respectively

Characterization and some Bioactivities of the Synthesized Citrus Pectin-ZnO Nanocomposites from Citron and Pomelo Fruits Peels

Pectin was extracted from the peels of citrus fruits (Citron: Citrus medica L. and Pomelo: Citrus maxima Merr.). In the extraction of fresh and dry pectin, acidic hydrolysis of the fresh or dry fruit peel samples was carried out followed by precipitation with ethanol. The yield percents of extracted pectins were 4.53 % (based on fresh peel) and 21.41 % (based on dried peel) from citron peels, and 3.03 % (based on fresh peel) and 9.18 % (based on dried peel) from pomelo peels. Extracted pectins were characterized by XRD, SEM, FT IR and TG-DTA analysis. The citrus pectin–ZnO nanocomposites were prepared by using co-precipitation method. Citron peel pectin-ZnO (CPPT-ZnO) nanocomposite (90.25 % yield) and pomelo peel pectin-ZnO (PPPT-ZnO) nanocomposite (64.95 % yield ) were prepared by using zinc nitrate and 0.2 M sodium hydroxide solution at 28 ± 0.5 oC. The stirring time require for CPPT-ZnO was found to be 1.5 h and that required for PPPT-ZnO was 2h.  The characteristics of the prepared citrus pectin-ZnO nanocomposites were studied by XRD, SEM, FT IR, TG-DTA, AAS and ED XRF (with C-H balance) spectroscopic methods.  The crystallite sizes of CPPT-ZnO and PPPT-ZnO were 32.30 nm and 24.46 nm determined by XRD analysis.The morphological observation of the SEM results revealed that the sizes of ZnO in CPPT-ZnO and PPPT-ZnO were 70.59 nm and 61.55 nm, and were embedded in the pectin matrix. AAS analyses showed that the zinc ion concentrations in CPPT-ZnO and PPPT-ZnO prepared at 28 ± 0.5 oC were 3.88 × 105 ppm and 5.27 × 105 ppm. Both of the tested samples (CPPT-ZnO and PPPT-ZnO) were observed to show antimicrobial activity with inhibition zone diameters ranged between 15 mm to 20 mm against two tested microorganisms such as Bacillus substilis and Staphylococcus aureus and only CPPT-ZnO aginsted Escherichia coli with inhibition zone diameters of 12 mm. Although both nanocomposites were active in tumor inhibitions, only the CPPT-ZnO was taken as positive in tumor inhibitions which shows inhibition percents 37.09 % (» 20%)