Effect of Sprouting on the Functional Properties and Amino Acid Profile of Two Bambara Groundnut (Vigna subterranea) Protein Isolates

Abstract

In this research, the effect of sprouting on the functional properties and amino acid profile of protein isolates from two Bambara groundnut landraces (Yobe black and Niger cream landraces) was studied. Proteins were isolated using alkaline extraction method. The amino acid profile and functional properties were investigated using standard analytical techniques. A significantly higher (p<0.05) foaming capacity was seen in sprouted samples (Niger cream 35.00; Yobe black 17.67) compared to the unprocessed samples (11.00 and 12.67 respectively). Similarly, the foaming stability of protein isolates from the sprouted samples was significantly (p<0.05) higher in both landraces studied; the foam was stable for up to 15 min. Differences were also observed between the protein isolates in terms of bulk density, swelling index, water absorption, oil absorption, emulsion capacity and emulsion stability; the differences were statistically insignificant (p>0.05). Aspartic acid, glutamic acid and leucine were the most abundant amino acids in the protein isolates studied. Differences were observed in the amino acid profile of Bambara groundnut proteins after sprouting. In Niger cream landrace, higher levels of all the amino acids were observed after sprouting. A similar trend was seen in Yobe black landrace after sprouting except for arginine, alanine and threonine that were slightly lower in processed compared to the unprocessed sample. The levels of total essential and non-essential amino acids of Niger cream landrace (48.27% and 50.86% respectively) and that of Yobe black landrace (47.75% and 48.45% respectively) were higher following sprouting. These findings indicate that sprouting improved the quality and properties of Bambara groundnut protein. Thus Bambara groundnut sprouting can provide a cheap protein source that can be used in alleviating malnutrition and in food industries where proteins are employed in preparations of food products.