Rao Shengqi, Jia Caochen, Lu Xiangning, Yu Yisheng, Wang Zhirong, Yang Zhenquan
College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, China.
Jiangsu Key Laboratory of Zoonosis, Yangzhou 225009, China.
Foods. 2024 Jun 1;13(11):1741. doi: 10.3390/foods13111741.
As a natural cationic peptide, Nisin is capable of widely inhibiting the growth of Gram-positive bacteria. However, it also has drawbacks such as its antimicrobial activity being susceptible to environmental factors. Nano-encapsulation can improve the defects of nisin in food applications. In this study, nisin-loaded egg white protein nanoparticles (AH-NEn) were prepared in fixed ultrasound-mediated under pH 3.0 and 90 °C. Compared with the controls, AH-NEn exhibited smaller particle size (112.5 ± 2.85 nm), smaller PDI (0.25 ± 0.01), larger Zeta potential (24 ± 1.18 mV), and higher encapsulation efficiency (91.82%) and loading capacity (45.91%). The turbidity and Fourier transform infrared spectroscopy (FTIR) results indicated that there are other non-covalent bonding interactions between the molecules of AH-NEn besides the electrostatic forces, which accounts for the fact that it is structurally more stable than the controls. In addition, by the results of fluorescence intensity, differential scanning calorimetry (DSC), and X-ray diffraction (XRD), it was shown that thermal induction could improve the solubility, heat resistance, and encapsulation of nisin in the samples. In terms of antimicrobial function, acid-heat induction did not recede the antimicrobial activity of nisin encapsulated in egg white protein (EWP). Compared with free nisin, the loss rate of bactericidal activity of AH-NEn was reduced by 75.0% and 14.0% following treatment with trypsin or a thermal treatment at 90 °C for 30 min, respectively.
作为一种天然阳离子肽，乳酸链球菌素能够广泛抑制革兰氏阳性菌的生长。然而，它也存在缺点，比如其抗菌活性易受环境因素影响。纳米包封可以改善乳酸链球菌素在食品应用中的缺陷。在本研究中，在pH 3.0和90℃的固定超声介导下制备了负载乳酸链球菌素的蛋清蛋白纳米颗粒（AH-NEn）。与对照组相比，AH-NEn表现出更小的粒径（112.5±2.85nm）、更小的多分散指数（PDI，0.25±0.01）、更大的zeta电位（24±1.18mV）以及更高的包封效率（91.82%）和载药量（45.91%）。浊度和傅里叶变换红外光谱（FTIR）结果表明，除了静电力之外，AH-NEn分子之间还存在其他非共价键相互作用，这解释了其结构比对照组更稳定的原因。此外，通过荧光强度、差示扫描量热法（DSC）和X射线衍射（XRD）结果表明，热诱导可以提高样品中乳酸链球菌素的溶解度、耐热性和包封率。在抗菌功能方面，酸热诱导并没有降低包裹在蛋清蛋白（EWP）中的乳酸链球菌素的抗菌活性。与游离乳酸链球菌素相比，用胰蛋白酶处理或在90℃热处理30分钟后，AH-NEn的杀菌活性损失率分别降低了75.0%和14.0%。
