Differential Scanning Calorimetry (DSC) Studies on Temperature-Denatured Protein Isolates from Two Varieties (DAS and BS) of Nigerian Cultivated Solojo Cowpea (Vigna Unguiculata L. Walp)
Abstract:
Calorimetry is the primary method utilized for checking the heating characteristics of samples in order to ascertain a correlation betwixt heat and precise tangible qualities of materials. Found to be a straighter approach to determine the ΔH connection with the method of interest. Investigation into the Differential Scanning Calorimetry (DSC) analyses on Temperature-denatured Protein Isolates from Two Varieties (DAS and BS) of Nigerian Cultivated Solojo Cowpea (Vigna Unguiculata L. Walp) was carried out. The Differential Scanning Calorimeter is used for the determination of the denaturation temperature (Td) of the sample which is taken as the temperature at the maximum peak. DSC measures enthalpy of unfolding resulting from heat denaturing. The transition midpoint Tm is taken as the thermal reading, in which 50% of the protein retains its indigenous configuration (shape), and the others remains denatured. Higher Tm values depicts a steadier molecule. Using DSC, additionally we can find the phase transition of the material, which is Tp (Denaturation temperature at the maximum peak). The onset temperature (To) of DAS ranged between 257.47±1.00 and 295.18±1.05oC, the end set temperature (Te) were between 293.38±0.45 and 313.85±0.62oC, while the peak temperature (Tp or Td) is the denaturation temperature. The denaturation temperature is also the temperature of thermal unfolding of the molecules of the protein. It ranged between 279.37±0.90 and 299.36±0.67 oC with the 24 h germinated isolate having the highest denaturation temperature while the 72-h germinated isolate had the lowest. The onset temperature (To) of DAS ranged between 257.47±1.00 and 295.18±1.05oC, the end set temperature (Te) were between 293.38±0.45 and 313.85±0.62oC, while the peak temperature (Tp or Td) is the denaturation temperature. The BS isolate similarly had its onset temperature ranging between 218.71±0.75 and 294.64±0.45oC, end set temperatures between 244.27±0.45 and 302.71±0.67 oC, while the denaturation temperature was between 232.36±0.5c and 298.56±0.78 oC. The raw BS however had the highest Td (Table 4. 98). DSC chart in the appendix. Enthalpy is connected with the energy needed for a transition, while Td is expressed as the temperature at which 50% of the molecules have gone through thermal transition. Heat profiles detected in the legumes were connected with disparity in the chemical configuration, thermal characteristics, and quality of the protein fractions. Noticed the existence of a denaturation peak (Td) at very high temperature which ranged between 195 and 210 °C. These values were lower than those of DAS and BS isolates [1]. The stability and the configuration of proteins were also observed to be governed by the equilibrium between the hydrophilic and hydrophobic side chains of amino acid residues of proteins.
