Evaluation of chemical composition, antioxidant potential and functional properties of carob ( Ceratonia siliqua L.) seeds

The interest in carob pod as an ingredient of functional foods is constantly increasing due to its beneficial health effect and functional properties. The aim of this study was to evaluate the chemical composition and antioxidant potential of carob seeds, as well as the functional properties of its isolated galactomannan fraction. The lipid, protein, carbohydrate and phenolic composition were analysed. The obtained results demonstrated that the main detected fatty acids were oleic (45.0%), linoleic (32.4%), and palmitic (16.6%) acid. The primary tocopherol in the tested tocopherol fraction was γ-tocopherol (53.1%). It was established that β-sitosterol (74.2%) and stigmasterol (12.8%) predominated in the sterol fraction. Carob seed was characterized by high protein (25.7%) content, while mannose and galactose were the dominating monosaccharides. Moreover, the isolated galactomannan from carob seed demonstrated good swelling properties-30.1 ml per g sample and oil-holding capacity (27.9 g/g sample). The total polyphenolic and flavonoids content of carob seeds was 1.76 mg Gallic acid equivalent/g dry weight and 0.30 mg quercetin equivalents/g dry weight, respectively. The carob seeds showed the highest antioxidant potential by cupper reduction assay-15.71 mM Trolox^® equivalent/g dry weight. The mineral composition was also defined as the macroelements Ca and Mg were the predominant minerals in the seed. The obtained results showed that carob seeds were a valuable source not only of phenolic compounds and antioxidants, but also of proteins, lipids, galactomannan with functional properties that could improve the nutritional value of foods in which are incorporated.

Keywords: Antioxidant activity; Ceratonia siliqua L.; Chemical composition; Seeds.