Physico-Functional Characterization of Flour and Protein Isolates from Nigeria Cultivated Solojo Cowpea [Vigna unguiculata (L.) WALP]

Abstract

Cowpea, an important protein food, is used for its nutritional and functional properties. A study was carried out to determine the physico-functional characteristics of Flours and Protein Isolates from Two (2) Varieties of Nigerian Cultivated Solojo Cowpea (Vigna Unguiculata L. Walp), to assess their potential use in the food industry. Functional properties were analysed which include Moisture, crude protein, crude fat, crude fibre, ash, carbohydrate and dry matter which were in the range of 9.15-9.83, 26.53-29.00, 2.50-3.99, 2.95-3.22, 4.24-4.80, 50.95-53.98 and 90.17-90.85% respectively. Bulk density ranged between 0.69 and 0.80 g/dm3. Water and oil absorption capacities ranged between 1.89 and 2.15, and 1.95 and 2.31 ml/g, respectively. Swelling power had values varying from 265 to 268% while foam capacity varied from 10.00 to 21.00 ml. The effect of ionic strength on foaming capacity (FC) and stability (FS) of the protein isolates using standard methods was carried out. Amino acids and molecular weight of the protein isolates were determined by amino acid analyser and sodium-dodecyl-sulphate-polyacrylamide-gel-electrophoresis. Surface morphology, functional group and thermal properties were determined for protein isolates by scanning electron microscopy, Fourier Transform Infrared (FTIR) spectrometry and differential scanning calorimetry, respectively. The results indicate that the two varieties of cowpea have great potential as functional agents in the food industry.