Evaluation of Physicochemical, Phytochemical and Chemical Composition of Methanolic Crude Oil Extracts from Ripe and Unripe Citrus sinensis Epicarp

Abstract

Sweet orange peels are commonly discarded as waste materials, although recent scientific research on the peel of Citrus sinensis has shown that it has considerable potential for conversion into useful community products, including antimicrobial agents, antioxidants, biochar, biogas and materials for water purification. This study aimed to compare methanolic crude oil extracts from ripe and unripe Citrus sinensis epicarp by analysing their physicochemical properties, phytoconstituents and fatty acid composition. All analyses were conducted using standard laboratory procedures. The oil yield from ripe Citrus sinensis epicarp extract was significantly higher (26.54%) than that from unripe Citrus sinensis epicarp extract (17.11%). Physicochemical analysis showed that ripe epicarp oil had higher saponification value (97.79 mg KOH/100 g), peroxide value (56.29 mg KOH/100 g) and free fatty acid value (21.82 mg KOH/100 g) than the unripe epicarp extract (87.74, 37.71 and 20.87 mg KOH/100 g, respectively). Both extracts contained bioactive constituents, including alkaloids, terpenoids, saponins, tannins and flavonoids, with ripe epicarp oil showing the highest flavonoid value (4.19%) compared with unripe epicarp oil (1.5%). GC-MS profiling indicated that the ripe epicarp extract was richer in unsaturated fatty acid derivatives, whereas the unripe extract contained more saturated fatty acid derivatives. Overall, the findings suggest that methanolic crude oil extracts from ripe and unripe Citrus sinensis epicarp may have nutritional, immunological and pharmaceutical relevance, supporting their potential use in functional food, nutraceutical and industrial applications.