The Improvement of Emulsifying Properties of Almond Kernel Protein by L-lysine and L-arginine and its Structural Effects

To improve the water solubility of Badam Kernel Protein (BKP) and expand its application scope, this study prepared BKP-L-Arginine (L-Arg)/L-Lysine (L-Lys) mixed emulsions by introducing L-Arg and L-Lys into BKP, respectively. Fourier transform infrared spectroscopy, intrinsic fluorescence spectroscopy, ultraviolet spectroscopy, and other analytical techniques were employed to characterize the structural and physicochemical properties of the mixed emulsions. The results demonstrated that L-Arg/L-Lys primarily enhanced the water solubility of BKP by elevating the pH value of the BKP solution. In comparison to pH-adjustment treatment, L-Arg/L-Lys treatment exhibited a more remarkable effect in improving the water solubility of BKP. L-Arg increased the water solubility of BKP from 67.83% to 83.57% (P<0.05); L-Lys increased it to 81.77%. The incorporation of L-Arg and L-Lys also significantly improved the emulsifying activity and stability of BKP. Specifically, L-Arg and L-Lys increased the Emulsifying Activity Index (EAI) by approximately 64.13 m²/g and 57.24 m²/g, respectively (P<0.05), and the Emulsifying Stability Index (ESI) by 37.00% and 29.02%, respectively (P<0.05). Modification with L-Arg and L-Lys can effectively overcome the inherent water solubility limitation of BKP and confer better emulsifying capacity to it. Owing to its excellent water solubility and emulsifying properties, the modified BKP is anticipated to serve as a high-performance natural protein additive, finding widespread application in emulsion-type food systems such as beverages, sauces, and dairy products, thus possessing broad application prospects.