Pectin Development from Citrus Peels and The Effect of Processing Conditions on the Extraction

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Addis Ababa University


The aim of this study was to extract pectin from two different varieties of citrus fruit namely Mexican lime (Citrus aurantifolia Swingle) and Lisbon lemon (Citrus limon “Lisbon”) and to investigate the effect of processing conditions on the process of extraction. Research samples were collected from Upper Awash Agro-Industry Enterprise. The raw material was prepared and pectin was extracted using nitric acid at different pH and temperature. Pectin was extracted from two varieties, at three different temperatures (40 °C, 60 °C, & 80 °C), and pH (1.0, 2.5, & 4.0). The experiments were carried out in water bath for two hours. Design-Expert 7.0.0 at three-level two-factor general factorial design was applied. A total of 27 experiments were conducted for each variety at various extraction conditions. From the analysis of experimental data the interaction effects were studied and the optimal process conditions, maximizing the percentage yield were found. Using nitric acid, the yield of pectin for Mexican variety varies from 4.6% ‐19.6% and from 5.4%-21% for Lisbon variety. It was also observed that with a decrease in pH the pectin yield increased. Similarly with an increase in extraction temperature, the pectin yield also increased. Maximum yield of 19.6% was obtained at pH 1.0 and temperature of 60 °C for Mexican variety whereas maximum yield of 21% was obtained at pH 1.0 and temperature of 60 °C for Lisbon variety. The best condition for extraction using nitric acid was at 60 °C for 2 h at pH 1.0. The pectin obtained from these methods was compared in terms of yield, physicochemical properties and chemical structure. Functional groups present in the pectin were investigated using Fourier Transform Infrared Spectroscopy (FTIR). The characterization of the extracted pectin was done by calculating the ash content, moisture content, equivalent weight, methoxyl content, anhydrouronic acid content and degree of esterification. Methoxyl content, anhydrouronic acid, and degree of esterification of extracted pectin varied from 3.41‐4.15%, 63.71‐74.27%, 27.62‐30.45%, and 6.14‐6.94%, 51.04‐67.89%, 51.34‐77.24% for Mexican and Lisbon varieties respectively. Preliminary feasibility study indicated that production of pectin from lemon peel is feasible with Birr 3.52 million TCI, with 17.75% ROI overall after tax, Birr 624,637 Npav, 2 year and 6 months payback period. Therefore, the above figures show industrial production of pectin from lemon peel is feasible and it would save valuable foreign exchange by reducing pectin imports. Key words: Pectin; Citrus peel; Processing conditions: Extraction; Yield



Pectin; Citrus peel; Processing conditions: Extraction; Yield