Legume Protein: Properties and Extraction for Food Applications

Abstract

Grain legumes are important sources of protein for nutritional and techno-functional applications. Their protein content is 18-50% protein on dry matter basis. Most of the protein is of the storage type, of which 70% are globulins. The globulin proteins are mainly legumins and vicilins, which are also known as 7S and 11S globulins, respectively. Several methods comprising wet and dry processes are used to extract protein from legumes. Choice of extraction method mainly depends on legume type and desired purity and functionality of extracted protein. Dry processing is suitable for starch-rich legumes, and involves fine milling and air classification. Wet processing uses solubility differences to extract and separate protein from non-protein components. The major extracted protein products are protein concentrate and isolate. Functional properties of protein depend on its amino acid profile, protein structure, hydrophobic, and hydrophilic effects. The major functional properties for food applications are solubility, water absorption capacity, oil absorption capacity, gelling, texturization, emulsification and foaming. They indicate ability of a protein to impart desired physico-chemical characteristics to food during processing, storage and consumption. The food products where isolated legume protein can be used include bakery products, plant based dairy alternative products, beverages and meat analogues.