Abstract—The current desire in food and industrial emulsification is the use of natural emulsifiers. Bambara groundnut flour (BGNF) and its starch (BGNS) will serve both emulsifying and nutritional purposes if found suitable. This current study was aimed at investigating the emulsifying properties of BGNF/BGNS. BGNS was extracted from the BGNF. Emulsions were prepared using a wide range of flour-oil-water and starch-oil-water composition as generated through the application of Response Surface (D-optimal) design. Prepared emulsions were investigated for stability to creaming/sedimentation (using the kinetic information from turbiscan) and flocculation/coalescence (by monitoring the droplet diameter growth using optical microscope) over 5 days. The most stable emulsions (one BGNF-stabilized and the other BGNS- stabilized) were determined. The optimal emulsifier/oil composition was 9g/39g for BGNF and 5g/30g for BGNS. The two emulsions had only 30% and 50% growth in oil droplet diameter respectively by day 5, compared to over 3000% in the unstable ones. The BGNF- stabilized emulsions were more stable than the BGNS-stabilized ones. Emulsions were successfully stabilized with BGNF and BGNS. Keywords—Bambara groundnut, coalescence, creaming, emulsification, emulsion, emulsion stability. I. INTRODUCTION HERE is growing interest by the food, pharmaceutical and cosmetic industries in replacing synthetic emulsifiers with natural ones. This is because natural emulsifiers are more biocompatible and could demonstrate satisfactory amphiphilic properties [1], [2]. The search for such natural products has yielded results with the use of the products of some leguminous plant like soybean and flaxseed in emulsion preparations [3]. The search for emulsifiers among natural plant/food products is particularly desirable due to their often non-toxic nature, affordability and availability, and their already established food and medicinal uses [3]. Bambara groundnut [BGN] (Vigna subterranea), a leguminous plant which belongs to the family fabaceae is an indigenous Africa plant that has been cultivated all over sub- Saharan Africa [4]. As important as BGN is as a source of food in many African communities, very limited studies have been conducted to assess its potential benefit to the food and pharmaceutical industries. Although there is no documented E. G. Gabriel is a Postgraduate student at the department of Chemical Engineering, Faculty of Engineering, Cape Peninsula University of Technology, South Africa (e-mail: gabrielebun@gmail.com). V. A. Jideani is an Associate Professor with the Department of Food Technology, Faculty of Applied Sciences, Cape Peninsula University of Technology, South Africa (e-mail: JideaniV@cput.ac.za). D. I. O. Ikhu-Omoregbe is a Professor and Head, Department of Chemical Engineering, Faculty of Engineering, Cape Peninsula University of Technology, South Africa (e-mail: IkhuOmoregbeD@cput.ac.za). study indicating the emulsifying capacity of Bambara groundnut (BGN), its rich blend of protein and carbohydrate suggests its potential as an emulsifier. In a study to analyze its nutritional composition, Doku [5] reported relatively high lysine content while another study by Amarteifio and co-workers [6] showed a breakdown of 53.1% carbohydrate, 17.4% protein, 6.1% fat, 6.1% fiber, and 3.4% ash, as well as low levels of calcium, iron, sodium and potassium. The protein in BGN is said to be richer as it has been reported to contain more essential amino acid (methionine) than any other legume [7]-[9]. In addition to the relatively high protein content in BGN, the total nutritional composition reflects an excellent balance unusual in single plant products. A number of food, pharmaceutical, and industrial products are prepared as emulsions [10]. Thus, BGN flour (BGNF) and starch (BGNS, if found suitable as emulsifier in food products, could impact added nutritional advantage [11]. In order to establish the suitability of a prospective emulsifier for emulsion preparation, various stability tests are have evolved. A number of instrumental methods have been developed to characterize the physicochemical properties of emulsions. Such instruments are employed to extract information on the change in droplet concentration, and size with time. The most commonly used instrumentations are based on the principle of light scattering in which a monochromatic beam of near infrared light is directed through an emulsion placed in a vertical flat-bottomed glass tubes [12], [13]. Thus, the percentage of transmitted or backscattered light measured as a function of the height of the emulsion provides an indication of changes in droplet concentrations along the height and can be used to determine creaming and/or sedimentation [14]. Due to the commercial availability of fully-automated analytical instruments based on this principle, optical profiling technique is one of the very popular ways for industrial characterization of gravitational separation in emulsions before such instability is visible to the eye [15]. One of such automated instrument (used in this study) is Turbiscan® which was employed in this study. In addition the growth of emulsion droplet through optical microscopy can provide indication of emulsion stability. The aim of this study was to investigate the emulsifying properties of BGNF and BGNS and to determine optimal concentration required to stabilize typical oil-in-water emulsion. Ebunoluwa G. Gabriel, Victoria A. Jideani, Daniel I. O. Ikhu-Omoregbe Investigation of the Emulsifying Properties of Bambara Groundnut Flour and Starch T World Academy of Science, Engineering and Technology International Journal of Biological, Biomolecular, Agricultural, Food and Biotechnological Engineering Vol:7, No:11, 2013 1054 International Scholarly and Scientific Research & Innovation 7(11) 2013 scholar.waset.org/1999.1/17379 International Science Index, Chemical and Molecular Engineering Vol:7, No:11, 2013 waset.org/Publication/17379