Effects and Mechanisms of Plastein Reaction on the Structure and Techno-Functional Properties of Sheep Plasma Protein

To enhance the application potential of sheep plasma protein (SPP) in the food industry, this study examined the structural and techno-functional properties changes in SPP caused by enzymatic hydrolysis and the plastein reaction. The results indicated that compared to enzymatic hydrolysis, the plastein reaction demonstrated a more pronounced effect in enhancing the processing characteristics and antioxidant activity of SPP. Research has found that following the plastein reaction modification, the plastein reaction product (SPHP) formed particles with a uniform size distribution. Meanwhile, this reaction enhanced intermolecular hydrophobic interactions and surface properties by altering the zeta potential and crystal structure of SPP. In terms of function, the oil absorption capacity of SPHP significantly increased, and exhibited superior foam stability and emulsifying activity over the pH range of 3 to 11. Furthermore, the contents of α-Helix, β-Turn, and random coil decreased after the plastein reaction, but the β-Sheet content increased. The structural changes resulted in a 19.1% and 31.4% increased in the DPPH• and ABTS• + scavenging rates of SPHP, while its Fe 2+ reducing ability was enhanced by 2.75 times. In summary, the plastein reaction effectively improved the techno-functional properties by regulating the molecular conformation of proteins, thereby providing new insights and technical support for the high-value utilization of plasma proteins. • Plastein reaction improved techno-functional properties of sheep plasma protein (SPP). • Plastein reaction enhanced the interfacial adsorption of SPP, increasing its emulsifying activity index from 2.09 m2/g to 3.47 m2/g at pH 5. • The DPPH and ABTS radical scavenging rates of SPP after plastein reaction increased 19.91% and 31.35%. • Structural modification induced by the plastein reaction enabled the Fe 2+ reducing ability of SPP by 2.75 times.