International Journal of Food Science and Nutrition

International Journal of Food Science and Nutrition


International Journal of Food Science and Nutrition
Vol. 6, Issue 3 (2021)

Effect of germination on the bulk density of flours and protein isolates from Solojo cowpea (Vigna Unguiculata L. Walp)


Olubamike Adetutu Adeyoju, Kayode Oyebode Adebowale, Bamidele Iromidayo Olu-Owolabi, Henry Okwudili Chibudike, Eunice Chinedum Chibudike

Effect of germination on nutritional and functional properties of flours derived from two (2) varieties of Solojo Cowpea (DAS-Dark-Ash Solojo and BS-Brown Solojo) were studied before and after dehulling of the germinated seeds while the ungerminated portion of the seeds served as the control. Both varieties (DAS and BS) investigated were soaked in distilled water and germinated at varying periods i.e. 0, 6, 24, 36, 48 and 72hrs. Protein isolates were then obtained from the treated and processed samples by isoelectric precipitation method which was subsequently followed by proximate and anti-nutritional analyses. Functional properties were also analysed. 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 calorimeter, respectively. Data were analysed by descriptive statistics and ANOVA at α0.05. Germination was observed to generally increase the OAC when compared with the control for full fat, defatted flours and protein isolates. The OAC values of the DAS and BS cowpea at 36 h, which is 2.26 g/g and 2.64 g/g respectively, were higher than those of the mung bean at 36 h which is 0.75 mL/g. Likewise at 24 h treatment DAS and BS cowpea sprouted gave a value of 1.89 g/g and 2.08 g/g respectively contrary to 1.25 mL/g for Mung bean. The bulk densities of germinated and dehulled legume flours were lower compared to control. The isolates had the bulk density varying between 0.36 to 0.50 g/cm3 for the LBD of DAS and 0.47 to 0.59 g/cm3 for PBD; while the BS isolate had for LBD 0.35 to 0.47 g/cm3 and 0.45 to 0.59 g/cm3 for PBD. Data showed that flours (full fat and defatted) had their WAC increasing with time of germination, the same was observed for the isolates of DAS and BS, with the germinated flour having better WAC than the non-germinated flour (0.95 to 1.94 g/g for FFDAS and 0.94 to 2.10 g/g for DFDAS; 1.41±0.02 to 2.14±0.02 g/g for FFBS; 1.46±0.02 to 2.33±0.01 g/g for DFBS; 2.27±0.06 to 3.41±0.03 g/g for DAS isolate and 2.21±0.09 to 4.15±4.15 g/g for BS isolate). The emulsification capacities of control samples ranged from 55 to 193 ml oil emulsified per gram of sample. On germination and dehulling, the emulsification capacities, activities and stabilities of samples increased significantly. There were increases in foaming capacities and reduction in foam stabilities of all the samples investigated on germination and dehulling. Thus, the study indicated that germination and dehulling improved the functional properties of legumes.
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