单宁酸与乳清分离蛋白结合对紫苏精油抗菌乳液稳定性的影响

Effect of Tannic Acid Binding to Whey Protein Isolate on the Stability of Antibacterial Emulsion of Perilla Essential Oil

探究单宁酸(tannic acid,TA)与不同种类蛋白共价结合对蛋白结构和紫苏精油(Perilla essential oil,PEO)纳米乳液稳定性的影响,并对乳液的抗菌性能进行评估。通过荧光光谱法和红外光谱法研究TA与不同种类蛋白的相互作用,结果表明TA与乳清分离蛋白(whey isolate protein,WPI)的结合位点最多(n=1.65),能够形成稳定的蛋白-TA复合物,利用其制备的乳液具有高稳定性。通过比较不同超声功率和油水比例制备的乳液,发现超声功率675 W、油水比1∶9条件下制备的乳液粒径最小((292.3±1.96)nm)、电位绝对值较大((-62.50±0.29)mV)、包埋率最高((74.51±0.35)%)。WPI-TA复合物与PEO之间的相互作用能够稳定乳液结构,乳液在4℃贮藏28 d仍具有较高的稳定性。乳液包埋能显著降低PEO的损失,相同条件下乳液中PEO的损失率仅为纯精油的1/3。本研究为蛋白-TA二元复合物的合成和易挥发物质的包埋提供了思路,拓宽了纳米乳液在食品工业中的应用。

This study systematically investigated the impact of covalent binding of tannic acid(TA)to different proteins on protein structure and the stability of a nanoemulsion of Perilla essential oil(PEO).Additionally,the antimicrobial activity of the nanoemulsion was assessed.The interactions between TA and various proteins were explored using fluorescence spectroscopy and Fourier transform infrared(FTIR)spectroscopy,revealing that TA exhibited the mostbinding sites(n=1.65)to whey protein isolate(WPI),forming a stable protein-TA complex.The emulsion prepared using TA had high stability.One-factor-at-a-time experiments showed that the emulsion prepared under the conditions of 675 W ultrasonic power and an oil-to-water ratio of 1:9 had the smallest droplet size of(292.3±1.96)nm,a relatively high absolute zeta potential value of(–62.5±0.29)mV,and the highest PEO encapsulation efficiency of(74.51±0.35)%.The interaction between WPI-TA complex and PEO could stabilize the structure of the emulsion,and the emulsion maintained high stability at 4℃for 28 days.Furthermore,emulsion encapsulation significantly reduced the loss of PEO,with the loss of PEO in the emulsion being only one-third of that of the pure essential oilunder the same conditions.This study provides newideas for future research on the synthesis of protein-polyphenol complexes and the encapsulation of volatile substances,laying a foundation for expanding the application of nanoemulsion in the food industry.