Studies On The Mechanism Of Alkaline Extraction And Preliminary Purification Of Protein From Caragana Korshinskii Kom.

Alkaline extraction of protein from abundant plant biomass is considered as an important way to improve the economic feasibility in a biorefinery. However, valorization of the protein fraction is challenging due to its low yield. In order to reveal the limiting operation parameters, an integrative analysis of kinetics and thermodynamics was used to investigate the alkaline extraction of protein from Caragana korshinskii Kom..Both a two-site kinetic extraction model and a second-order model indicated that particle size is the most pivotal factor affecting protein extraction yield. A decrease of particle size from20-40to60-80mesh resulted in a decrease of C2(protein yield in the slower process) from14.02to7.32mg·g-1, but a great increase of C1(protein yield in the faster process) from20.61to59.07mg·g-1. However, the protein yield was dominated by the faster process when the average particle size is under80mesh. The maximum initial extraction rate was72.20mg·g-1·min-1with the particle size of60-80mesh, almost9-fold of that with20-40mesh. Thermodynamic analysis revealed that the enthalpy change (△H) and entropy change (△S) in the protein extraction process were calculated as21.08kJ·mol-1and84.76J·K-1, respectively. The standard free energy (△G) had a magnitude from-3.77to-5.46, suggesting that the extraction process was spontaneous and feasible. Antioxidant activities of protein isolates from C. korshinskii Kom.(CPI) were also evaluated, and the results indicated that CPI exhibited strong scavenging capacity for DPPH radical. The DPPH radical scavenging activity of CPI could reach87%with1.5mg·mL-1. After alkaline extraction, CPI were purified by a DEAE-cellulose anion-exchange column and two fractions, CPI-A and CPI-B, were charaterized by SDS-PAGE. The results showed that CPI-A and CPI-B had three and four main bands respectively.