EFFECTS OF ISOLATION CONDITIONS ON THE FUNCTIONAL PROPERTIES OF AFRICAN YAM BEAN (SPHENOSTYLIS STENOCARPA HOCHST. EX A. RICH.) PROTEINS LAWRENCE A. AROGUNDADE 1,3 , CATHERINE O. EROMOSELE 1 , IGHODALO C. EROMOSELE 1 and OLADIPO ADEMUYIWA 2 1 Chemistry Department, Federal University of Agriculture, Box 28, FUNAAB Post Office, Abeokuta, Ogun State, Nigeria 2 Biochemistry Department, Federal University of Agriculture, Abeokuta, Ogun State, Nigeria 3 Corresponding author. TEL: +234-70-35080660/+86-18-210123943; FAX: +86-10-62815541; EMAIL: aroglaw@yahoo.com Accepted for Publication January 10, 2012 Received for Publication December 7, 2010 doi:10.1111/j.1745-4549.2012.00674.x ABSTRACT African yam bean (Sphenostylis stenocarpa) calcium proteinates and isoelectric pro- teins were characterized to determine their molecular constitution and functional properties. The electrophoretogram of S. stenocarpa proteins obtained from sodium dodecyl sulfate polyacrylamide gel electrophoresis under reducing condition showed that both calcium proteinates and isoelectric proteins had three prominent molecular mass, i.e., 29, 43 and 53 kDa. Calcium precipitation of the protein had a blueshift effect on the protein UV absorption with a shift from 269 nm to 257 nm, whereas UV absorption maximum for isoelectric precipitated protein remained 269 nm as obtainable with flour protein and, thus, no conformational change was associated with isoelectric precipitation. Bulk densities, water and oil absorption capacities of the isolates were in the ranges of 0.76–0.86 g/mL, 2.0–2.33 g/g protein and 0.78–0.99 g/g protein, respectively. Its gelation and water absorption properties were better than or comparable to those of soy bean and some other legumes. PRACTICAL APPLICATIONS African yam bean (Sphenostylis stenocarpa) is a crop grown in some countries in Africa. It produces its edibles (seed grains, root and leaves) in abundance and seems capable of delivering record quantities of protein from soils normally considered mar- ginal. Moreover, the protein is of good nutritional quality. Production of protein iso- lates from this crop for food formulation and new product development is being envisaged.Its functional attributes examined under this study showed that it might be put to similar use in the food industry as obtainable with soy bean, where high gelling property is of interest in the formulation of value-added food products. INTRODUCTION African yam bean (Sphenostylis stenocarpa) is one of the legumes grown in Africa that is well adapted to lowland tropical agro-ecosystems. The crop is underutilized, possibly because of its hard-to-cook phenomenon and lack of knowl- edge on its industrial utilization potentials. Although the seed grain crude protein is lower than that of soybeans, its amino acid spectrum is similar to it (Okigbo 1973). This crop has attracted research interest in the recent times due to its nutri- tional content (Ofuya et al. 1991; Ene-Obong and Obizoba 1996; Oshodi et al. 1997). The production of African yam bean protein isolate would provide the food industry with a new high-protein food ingredient for product formulation and food fortification. Food fortification with protein is criti- cally needed in many African countries as the low income earners, which dominate the growing population, cannot afford the expensive animal protein. Application of any legume protein as food supplement and/or functional agent in the food industry requires that such vegetable protein must be well-known in terms of its nutritional profile, physicochemical and functional Journal of Food Processing and Preservation ISSN 1745-4549 1 Journal of Food Processing and Preservation •• (2012) ••–•• © 2012 Wiley Periodicals, Inc.