Proximate composition, amino acid composition, fatty acid composition, nutritional properties, and antioxidant and anti-amylase potential of Citrus peels obtained from healthy fresh fruits

Citrus peels from fresh, healthy fruits were comprehensively characterized to assess their physicochemical, compositional, nutritional, and functional properties and evaluate their potential as functional food ingredients. The dry matter was predominantly composed of structural polysaccharides (pectin, cellulose, and hemicellulose), along with proteins, lignin, lipids, and bioactive compounds including polyphenols, flavonoids, and carotenoids. Amino acid profiling revealed high levels of proline, aspartic acid, glutamic acid, serine, and glycine, with substantial proportions of essential and glucogenic amino acids. The lipid fraction was enriched in polyunsaturated (linoleic and α-linolenic), monounsaturated (oleic and palmitoleic), and saturated fatty acids (palmitic and stearic), resulting in favorable nutritional lipid indices. Essential oils were dominated by limonene and oxygenated monoterpenoids such as linalool and α-terpineol. Functionally, citrus peel exhibited strong antioxidant capacity and α-amylase inhibitory activity. The aqueous extract displayed negative ζ-potential, microscale particle distribution, and desirable techno-functional properties, including swelling, emulsifying capacity, and shear-thinning behavior. These findings highlight citrus peel as a sustainable source of dietary fiber and bioactive compounds suitable for low-calorie functional food and nutraceutical applications.