Legumes are valued worldwide as a sustainable and inexpensive meat alternative and are considered the second most important food source after cereals. Legumes are nutritionally valuable, providing proteins (20-45%) with essential amino acids, complex carbohydrates (±60%) and dietary fibre (5-37%). Legumes also have no cholesterol and are generally low in fat, with ±5% energy from fat, with the exception of peanuts (±45%), chickpeas (±15%) and soybeans (±47%) and provide essential minerals and vitamins. In addition to their nutritional superiority, legumes have also been ascribed economical, cultural, physiological and medicinal roles owing to their possession of beneficial bioactive compounds. Research has shown that most of the bioactive compounds in legumes possess antioxidant properties, which play a role in the prevention of some cancers, heart diseases, osteoporosis and other degenerative diseases. Because of their composition, legumes are attractive to health conscious consumers, celiac and diabetic patients as well as consumers concerned with weight management. The incorporation of legumes in diets, especially in developing countries, could play a major role in eradicating proteinenergy malnutrition especially in developing Afro-Asian countries. Legumes could be a base for the development of many functional foods to promote human health.

Fiber is a mixture of nonstarch polysaccharides that resist digestion by enzymes in the gastrointestinal canal. Some known methods of extracting fiber from plant sources include dry processing, wet processing, chemical, gravimetric, enzymatic, physical, microbial or a combination of these methods. Modified wet milling is the most cost effective in the wet milling group as it uses minimal chemicals, produces high purity products and uses less water than the other methods. The purity of fibers extracted using the modified wet milling method range from Downloaded by [Deakin University Library] at 12:44 12 August 2015 A c c e p t e d M a n u s c r i p t 2 49.7% -89.6%. An ideal extraction method should be affordable and produce fibers of high purity.

The objectives of this study were to extract soluble and insoluble dietary fibres from four Bambara groundnut (BGN) varieties (black-eye, brown-eye, brown and red) using the wet milling method and evaluate their physicochemical properties. The swelling capacities of brown-eye (6.5 g/mL) and black-eye (6.2 g/mL) fibres were higher (p≤0.05) than those of red (6.0 g/mL) and brown (5.5 g/mL) fibres while the water holding capacities of black-eye and brown-eye fibres (2.84 g and 2.83 g water/g sample) were higher (p≤0.05) than those of brown and red fibres. The bulk densities of insoluble dietary fibres (IDFs) and soluble dietary fibres (SDFs) ranged between 0.57 g/mL (red) to 0.67 g/mL (brown-eye) and 0.46 g/mL (brown-eye) to 0.57 g/mL (black-eye), respectively. The oil binding capacities (OBCs) of SDFs ranged between 2.78 g oil/g sample (brown) and 4.03 g oil/g sample (brown-eye) while the OBC of all IDFs did not differ (p>0.05), ranging between 1.52 g oil/g sample (brown) and 1.40 g oil/g sample (brown-eye and black-eye). Black-eye and brown-eye dietary fibres had higher phenolic and total sugar content. The findings of this study indicate the potential of BGN fibres in food systems as fat replacers, emulsion stabilisers, water binders, bulking agents, thickeners and nutritional additives.

There has been an increase in consumer demand for healthy food products made from natural ingredients. This demand has been partly addressed by the substitution of natural alternatives to synthetic ingredients. One such example in this endeavour, is the study of the application of natural biopolymers as food emulsion stabilisers. When biopolymers such as proteins and polysaccharides or their complexes are applied as emulsion stabilisers, they exhibit different modes of action. These include acting as emulsifiers (polypeptides), increasing the viscosity of the medium (polysaccharides), reducing coalescence by coating individual droplets as well as acting as weighting agents (polysaccharides and polypeptides). Biopolymers can be covalently complexed using chemical, enzymatic or thermal treatments. These treatments generally increase the robustness and solubility of the final complexes. Biopolymer complexes have been reported to show higher stability to varying temperatures, pH and ionic strength. When two incompatible biopolymers are mixed, either associative or segregative phase separation occurs. The former involves separation of oppositely charged polymers due to electrostatic repulsion and the latter involves separation of similarly charged or neutral biopolymers. In this chapter, the stabilising effect, complexation, mode of action, phase behaviour and future application of biopolymers in emulsions are discussed.

Soluble dietary fibres (SDFs) [30% (w/w)] from four varieties of Bambara groundnut (BGN), viz. black-eye, brown-eye, brown and red were used to stabilize orange oil beverage emulsions at 6% (w/w) orange oil. Emulsion stability was studied using Turbiscan MA 2000 and in terms of oil-droplet size characterization. The volume-surface mean diameter (d 3,2) and equivalent volume-mean diameter (d 4,3) of the four emulsions ranged between 2.68-4.38 µm and 17.09-18.62 µm, respectively. Emulsions stabilized with black-eye-SDF and brown-SDF possessed the least and highest d 3,2 and d 4,3 , respectively. The d 3,2 and d 4,3 of all four emulsions were significantly (p < 0.05) different. Emulsions were relatively stable to creaming and destabilized mainly by phenomenon involving oil-droplet aggregation. The backscattering flux of the emulsions ranged from 72.9% (brown-SDF stabilized emulsion) to 85.0% (black-eye-SDF stabilized emulsion). All four BGN SDFs greatly indicated their potential in stabilizing beverage emulsions.