Extraction and characterization of pectin from fruit peels of Irvingia gabonensis and pulp of Cola milleni and Theobroma cacao as precursor for industrial applications

Abstract

Pectin is a complex polysaccharide that makes up about one third of the cell wall of higher plants. It was extracted from fruit peels of Irvingia gabonensis and pulp of Cola milleni and Theobroma cacao using acid extraction and alcohol precipitation methods. The effects of temperature and time on the yield and physicochemical properties of the extracted pectin were evaluated. Optimum yields of pectin from C. milleni, I. gabonensis, and T. Cacao were 10.73%, 19.83%, and 11.73% respectively at extracting period of 150 min and temperature of 100 °C. Although there was significant difference in moisture content, degree of esterification, equivalent weight, and methoxyl content of the extracted pectins, there was no significant difference in yield, protein, and ash content at 95% confidence interval. The monosaccharide composition of the three pectins shows that the extracted pectin composed of galacturonic acid and minor neutral sugars. Major functional groups in the extracted pectin show peaks in the region between 1000 and 2000 cm−1. The bands observed between 1627–1651 cm−1 and 1739–1793 cm−1 indicated the presence of the carbonyl group stretching. The surface morphologies of the extracted pectins show irregular shapes, non-smooth surfaces, and unequal sizes which also reveals more silica nodes in cocoa pulp pectin than in other pectins. Thermogravimetric analysis of the pectin samples shows multi-step stages of thermal decomposition, indicating wide range of thermal stability. The overall results specified that the pectins extracted from these plants are suitable for industrial applications.