Chemical, Functional, and Nutritional Properties of Egusi (Colocynthis citrullus L.) Seed Protein Products

Abstract

Egusi (Colocynthis citrullus L.) kernels contain 52.0% oil, 28.4% protein (60% in defatted flour), 2.7% fiber, 3.6% ash, and 8.2% carbohydrate. They are good sources of essential amino acids, especially arginine, tryptophan and methionine, vitamins B1, B2, and niacin, and S, Ca, Mg, Mn, K, P, Fe, and Zn. The oil contains mostly oleic (15.9%) and linoleic (62.8%) acids. Protein isolates that differ in gel electrophoretic patterns and amino acid content can be prepared from the flour in one- or two-step water and sodium hydroxide extractions. The water and oil holding capacities of the flour are 0.7 and 2.6 ml/g, respectively. Thick (mayonnaise-type) emulsions form in the alkaline pH range and a stable foam forms at pH 5.0. Nutritionally, lysine is the most limiting amino acid (chemical score, 52.4).