Amino acid composition (AA) and SDS-PAGE Electrophoresis of Flour & Protein Isolates from Two Varieties (DAS & BS) of Nigeria Cultivated Solojo Cowpea [Vigna unguiculata (L.) WALP] (Published)
The amino acid configuration of the protein determines the nutritional value of the protein. Table 1-9 showed the amino acid composition of germinated DAS and BS flour and isolate. The value of the essential amino acid for the flours and isolate was generally highest for Leucine; this was followed by lysine and then phenylalanine. Sprouting was observed to cause increment in the AA quantity of the samples. The lysine content of germinated DAS flour increased from 6.85 to 7.91 g/100 g after 72 h of germination, while that of BS went from 6.97 to 8.20 g/100 g. The Isolates of the two varieties also increased with germination, the isolate of DAS g/100g obtained a value of 6.8 and 6.7 g/100 g respectively for the flour and protein isolate of their cowpea variety. The sulphur containing amino acids too also increased with germination, methionine of germinated DAS flour increased marginally from 0.65 to 0.86 g/100 g, BS flour from 0.65 to 0.91 g/100 g. The isolate of DAS from 1.15 to 1.37 g/100 g and BS isolate from 1.25 to 1.56 g/100 g. The approximate amount of proline, an EAA, was also observed to be apparently increased in germinated peanut cotyledons and sprouts. This goes to show that germination truly improved the AA content of the legumes. The non- essential amino acid had the glutamic acid having the greatest value, followed by aspartic acid, then arginine, while the rest followed at various levels. The non-essential amino acids were also improved by germination. It was also observed that improvement in the AA content of different fractions of the protein isolate from the two (2) varieties of solojo cowpea increased with germination. All the samples had their amino acid quantity reaching and surpassing the FAO/WHO requirement for both children and adult especially after germination except for methionine which is slightly short of the standard after germination furnishing the value of lysine in the range of 5.98-6.05 and isoleucine value in the range of 4.01-4.18. In germination, protein disintegration takes place because the plant makes use of the stored protein as point of supply of nitrogen and carbon for bio –molecule synthesis. Here, lower molecular weight polypeptides were not evident this may likely be due to the higher molecular weight proteins which might have broken down during germination into short chain peptides and amino acid which were not detected by electrophoresis analysis. SDS-PAGE electrophogram confirmed that high molecular weight bands almost disappear after germination of lupin,
Citation: Adeyoju O.A., Adebowale K.O., Olu-Owolabi B.I.,Chibudike H.O., and Chibudike C.E. (2022) Amino acid composition (AA) and SDS-PAGE Electrophoresis of Flour & Protein Isolates from Two Varieties (DAS & BS) of Nigeria Cultivated Solojo Cowpea [Vigna unguiculata (L.) WALP], European Journal of Food Science and Technology, Vol.10, No.4, pp.24-38
Keywords: BS, DAS, Functional, Nutritional, Solojo Cowpea, Under-utilised legumes, Vigna unguiculata, protein isolate
Effect of Ionic Strength on Emulsion Activity (EA) of Isolates from Two Varieties (DAS & BS) of Nigerian Cultivated Solojo Cowpea (Vigna Unguiculata L. Walp) (Published)
Concentration Effect on activity of emulsion (EA) and stability of emulsion (ES) of the various samples was investigated. Emulsifying Activity (EA) of raw (native/ control) and germinated Dark-ash Solojo Cowpea (FFDAS, DFDAS, FFBS and DFBS flours; DAS and BS protein isolate) were all concentration dependent. The 6h DFDAS flour and raw DAS isolate both had the emulsifying activity increasing up to 2% w/v before initial fall of activity with increase in concentration. FFDAS Raw, 24 h, 48 h and 72 h; DFDAS 24 h, 48 h, 72 h; FFBS 6 h, 24 h, 48 h, 72 h; DFBS 6 h; 24 h; DAS 48 h; BS 36 h, 48 h and 72 h all had their EA increasing with rise in concentration up to 4%w/v; while FFDAS 36 h; DFDAS Raw, 36 h; FFBS Raw, 36 h; DFBS 36 h, 48 h, 72 h; DAS 6 h, 36 h; BS Raw, 6 h and 24 h germinated flour and protein isolates went up to 6% w/v before additional rise in concentration brought about a decrease in value. Only DAS 24 h germinated protein isolate gave a rise of up to 8% w/v before decline in emulsifying activity took place. The values of the emulsifying activity ranged between 42.45±2.54 and 49.30±0.96%; 43.48±4.35 and 47.68±0.37%; 43.75±0.55 and 60.57±2.10%; 44.37±1.57 and 47.74±0.36%; 41.36±3.66 and 78.26±4.35%; 42.22±2.41 and 67.26±1.96%, for FFDAS, DFDAS, FFBS, DFBS, DAS and BS respectively. The increase in EA with germination shows increased solubility. Germination caused the exposure of the functional groups inside the protein matrix due to the unfolding of the protein matrix and this brought about increased synergy at the protein oil interface. Protein being a surface-active agent is capable of quickly moving to the oil – water point of linking where it is adsorbed to create a shielding membrane via intermolecular interaction. The solubility of the protein in the aqueous phase makes this possible. Once protein quantity is small, protein adhesion at the oil–water border is by moving from area of high concentration to low concentration (Diffusion controlled). Decrease in emulsifying activity was observed among DFBS Raw, DAS 72 h, and FFDAS 6 h up to 2%, 4% and 8% respectively. Germination was observed to improve EA of the Solojo flours and isolates. Varietal difference was also observed in the effect of germination on EA, FFBS was found to have a higher EA than FFDAS. The isolate had the DAS having a better EA than the BS. This could be due to the degree of uncoiling of the protein molecule and also the quantity of hydrophilic and non-polar constituent on the interface of the molecule. The foaming capacity (FC) for FFDAS increased with germination except at lower concentration of 2-4%. That of DFDAS showed a better response. The FC was higher than that of the FFDAS, this could be as a result of the exposure of more hydrophilic sights as a result of defatting. The DFBS likewise exhibited a higher FC compared to that of FFBS. The FC of the flours of brown solojo was found to be higher than that of the dark-ash solojo cowpea. The high foaming capacity (FC) at highly acidic and alkaline pH was probably as a result of the rise in total charge on the protein, bringing about the lowering of the non-polar inter- actions but increasing protein pliability, making the protein to disperse speedily to the junction between air and water enclosing particles of air thereby encouraging formation of foam. This observation proved the authenticity that foaming property depends on protein solubility.
Keywords: Nutraceuticals, Nutritional composition, Solojo Cowpea, Under-utilized legumes, essential amino acids, food industry