卵清蛋白
化学
钠
傅里叶变换红外光谱
Zeta电位
X射线光电子能谱
核化学
纳米颗粒
材料科学
生物
核磁共振
有机化学
化学工程
纳米技术
免疫学
物理
工程类
免疫系统
作者
Zhouyi Xiong,Maojie Zhang,Meihu Ma
标识
DOI:10.1016/j.foodhyd.2016.03.007
摘要
In this work, ovalbumin (OVA) was phosphorylated by dry-heating at three different pH values (5.0, 7.0 and 9.0) and 45 °C for 12 h in the presence of sodium tripolyphosphate (STP). The results indicated that, when compared with native OVA (N-OVA), the zeta potential absolute value of phosphorylated OVA (PP-OVA) increased from 2.13 mv (N-OVA) to 13.57(PP-OVA-pH5.0), 16.00(PP-OVA-pH 7.0) and 11.20 mv (PP-OVA-pH 9.0); the volume-weighted mean diameter (D [4,3])of emulsions stabilized by the N- and PP-OVA decreased from 70.22 μm (N-OVA) to 37.16(PP-OVA-pH 5.0), 16.21(PP-OVA-pH 7.0) and 43.52 μm (PP-OVA-pH 9.0); and PP-OVA emulsions exhibited a more narrow monomodal size distribution and a smaller particle size than those of N-OVA, with the corresponding emulsifying activities index (EAI) increased from 92.71(N-OVA) to 142.51(PP-OVA-pH5.0), 224.88(PP-OVA-pH 7.0), and 150.97(PP-OVA-pH 9.0), respectively. The microscopic observation showed that the emulsion droplets of PP-OVA were more densely and uniformly distributed than those of N-OVA. Furthermore, characterization of PP-OVA by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and 31P nuclear magnetic resonance (31P NMR) revealed that phosphate groups were bound to the -OH on serine and threonine and the -NH2 on lysine and arginine, with covalent interactions (C–O–P and C-N-P bounds) formed between OVA and STP. This study demonstrated that the introduction of phosphate groups could increase the amount of negative charge and intermolecular repulsion, decrease the particle size of droplets and improve the emulsifying ability of PP-OVA.
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