Chemical composition and active compounds in Bitter orange (Citrus aurantium) peels

Abstract

Background: Citrus fruits are significant to functional food science for two main reasons: the diversity of their chemical and nutritional content and their organic residues, which increase their economic value. The present study was conducted on the aqueous extract of dried bitter orange (Citrus aurantium) peels. It aimed to determine the overall chemical composition of the extract, and identify any bioactive compounds that may hold nutritional and industrial value.

Objective: This study aimed to determine the overall composition of locally grown bitter orange peels and to determine the active ingredients that can be extracted from them both qualitatively and quantitatively.

Results: The results indicated that the percentages of moisture, carbohydrates, protein, fat, fiber, and ash reached 5.34%, 70.25%, 1.95%, 3.50%, 15.38% and 3.58%, respectively. The pH value for the aqueous peels extract was 4.30. Qualitative results indicated the presence of glycosides, saponins, phenols, flavones, coumarins alkaloids in the extract of bitter orange peels. Quantitative results, obtained via HPLC analysis, included the concentrations of active compounds in the prepared extract, which varied according to the type of extract. The aqueous extract of bitter orange peels contained the active compounds gallic acid (0.019 ) µg/mL, vanillic acid (1.149) µg/mL , caffeic acid (0.077) µg/mL, 4-hydroxybenzoic acid (3.390) µg/mL, coumaric acid (0.033) µg/mL, catechol (0.002) µg/mL, naringenin (0.330) µg/mL, ferulic (0.320) µg/mL, chlorogenic (0.262) µg/mL of flavonoids, and vitamin C (448 µg/mL).

Novelty: This study highlights the underutilized potential of bitter orange (Citrus aurantium) peels by demonstrating their rich content of bioactive compounds, including multiple phenolic acids and flavonoids. Through qualitative and chromatographic analysis, the research identifies nutritional and medicinal components, positioning bitter orange peels as a valuable resource for functional food development.

Conclusion: The bitter orange peel extract contained several types of alkaloids, the most important of which are: methaqualone, promethazine, epigallocatechin, tramadol, and berberine. Additionally, bitter orange peel contains both water-soluble and fat-soluble vitamins. For this reason, the vitamin C levels were also very high in the aqueous extract of bitter orange peel.

Keywords: bitter orange, peel extract, chemical compounds, phenolic compounds, vitamins.