Castor oil (Ricinus communis): a review on the chemical composition and physicochemical properties

Abstract

Increasing world population has markedly increased the demand for vegetable oils for domestic and industrial purposes. Plant-based vegetable oils have been identified as one of the oils with high nutritive value. Castor plant is one of the oilseed with rich oil content owing to its high monounsaturated fatty acid and bioactive compounds. Its fatty acid profile constitutes mainly of ricinoleic acid and other minor acids such as stearic, palmitic, and oleic acid. Ricinoleic acid of castor oil is unique among all other vegetable oils, making it attractive for a wide spectrum of applications. The predominant triglyceride component in the oil is triricinolein. Minor biological compounds including carotenoid, tocopherol, tocotrienol, phytosterol, phospholipid, phytochemical, and phenolic compounds are present in castor oil. These compounds offer oxidation stability, anti-inflammatory, and antioxidant properties to the oil. The acid, anisidine, iodine, viscosity, and saponification values indicate that castor has good oil quality compared to other vegetable oils. Castor oil composition is influenced by the area of production and method of extraction adopted. The chemical structure of castor oil is centered on the ricinoleic acid and three major functional groups linked by glycerol moiety. More research on the oil’s component is being investigated nevertheless efficient and eco-friendly extraction methods are required. This review, therefore, summarizes the castor oil composition namely the triglyceride, various fatty acids and bioactive compounds, extraction methods, as well as its physicochemical properties.

Keywords:
castor oilseed; fatty acids; phytosterols; ricinoleic acid; tocopherols