Extraction and Comparative Assessment of the Physicochemical Properties of Pectin From Four Fruit Wastes in Ghana

Substantial amounts of waste and by-products are generated annually from the fruit processing industry - an issue with detrimental environmental, socioeconomic and health impacts. Concerted efforts are currently geared towards curtailing this canker, particularly waste valorisation into eco-friendly, economical and sustainable biopolymers such as pectin. This study focused on the extraction and comparative analysis of the physicochemical properties of pectin from four fruit wastes: Mangifera indica L. (Keitt variety), Carica papaya (Solo variety), Ananas comosus (MD2 variety) and Citrus limon (Eureka variety). Pectin was extracted using the conventional citric acid and NaOH processes. Subsequently, the yield, proximate contents and physicochemical properties of the extracted pectins were analysed and compared. The orthogonal data transformation tool, principal component analysis (PCA), was used to highlight relationships between the extracted pectins. Rapid-setting high methoxyl (DE > 72%) and pharmaceutical-grade pectins were extracted (yield ranging from 6.72% to 26.60%) irrespective of the extraction method. All the pectins conformed to high-quality standards (anhydrouronic acid content > 60%, ash content < 2% and moisture content < 5%). FT-IR analysis revealed that the primary structure of pectin was maintained in all samples. Moreover, all the pectins were sparingly soluble in water (25°C) and exhibited statistically significant (p < 0.0001) variations in the swelling and water-holding properties. PCA demonstrated the clustering of pectins from the same sources despite extraction techniques, highlighting that despite the variations, pectins from the same source exhibit some degree of similarity. The present study presents alternative high-quality pectins with good physicochemical properties that can be utilised in pharmaceutical dosage forms.