The potential of bambara groundnut ( Vigna subterranea) in vegetable milk production and basic protein functionality systems

Abstract

Bambara groundnut is an underutilized African legume which provides security for many farmers as it shows considerable drought resistance. The possibility of producing a vegetable milk for local use or an extracted protein with functional properties for use in food processing applications was studied. Milks were made by soaking bambara groundnut overnight, homogenizing and removing insoluble material to give a milky liquid. The beany taste could be removed by dry-frying the beans after soaking but before homogenization. Milks produced in this way were preferred by the taste panel (composed largely of Africans). A comparison of bambara groundnut milk and milks prepared from cowpea, pigeonpea and soybean was made using sensory and instrumental analysis. Sensory analysis showed all milks were acceptable with bambara groundnut ranked first in the preference trial. The lighter colour of bambara groundnut milk was more acceptable to the taste panel but there was no correlation between viscosity measured on a viscometer and viscosity perceived by the taste panel. A crude protein isolate (76% protein) from bambara groundnut was subjected to standard protein functionality tests but it was inferior to the standard used (egg albumen and soy isolate). It did not show any useful properties in emulsification, foam stabilization, or gelation or in a model cake system.