食品科学 ›› 2019, Vol. 40 ›› Issue (21): 28-34.doi: 10.7506/spkx1002-6630-20180925-270

• 基础研究 • 上一篇    下一篇

热处理对酶改性蛋黄液乳化性的影响及拉曼光谱分析

徐楠,赵英,迟玉杰   

  1. (东北农业大学食品学院,黑龙江 哈尔滨 150030)
  • 出版日期:2019-11-15 发布日期:2019-12-02
  • 基金资助:
    “十三五”国家重点研发计划重点专项(2018YFD0400304);现代农业产业技术体系建设专项(CARS-40-K25)

Effect of Heat Treatment on Emulsifying Properties and Raman Spectroscopic Characteristics of Enzymatically Modified Egg Yolk Liquid

XU Nan, ZHAO Ying, CHI Yujie   

  1. (School of Food Science, Northeast Agricultural University, Harbin 150030, China)
  • Online:2019-11-15 Published:2019-12-02

摘要: 蛋黄液对热敏感,64 ℃左右开始变性形成凝胶,加工过程中的热处理会导致其乳化性质下降,限制了其在食品工业中的应用。因此,本实验研究不同热处理条件(60、65、70 ℃均处理4 min)对酶改性蛋黄液乳化性质及蛋白质结构的影响。结果表明:随着热处理温度的升高,蛋黄液的乳化活性呈现下降的趋势,所形成的乳化体系平均粒径表现出增大的趋势。同一热处理条件下,酶改性蛋黄液的乳化活性及乳化稳定性均显著高于未改性蛋黄液(P<0.05),酶改性蛋黄液所形成的乳化体系粒径明显减小,粒径分布更加接近正态分布。拉曼光谱分析结果显示,在不同热处理条件下酶改性蛋黄液中蛋白质二级结构发生变化,在65 ℃以下随温度升高α-螺旋结构相对含量显著升高,无规卷曲结构相对含量显著下降(P<0.05);其色氨酸残基、酪氨酸残基及脂肪族疏水基团较未改性蛋黄液更倾向于暴露。采用偏最小二乘法建立了基于拉曼光谱的蛋黄液乳化性质模型,结果表明蛋黄液中蛋白质二级结构及构象变化(特别是低密度脂蛋白的构象变化)对蛋黄液乳化性质影响最大。

关键词: 蛋黄液, 酶改性, 乳化性, 拉曼光谱, 热处理

Abstract: Egg yolk liquid is thermally sensitive and begins to denature at around 64 ℃, forming a gel. For this reason, heat treatment during processing can deteriorate the emulsifying properties of egg yolk liquid, limiting its application in the food industry. In this experiment, the effects of different heat treatments (at 60, 65 or 70 ℃ for 4 min) on emulsifying properties and protein structure of enzymatically modified egg yolk liquid were studied. The results showed that the emulsifying activity index (EAI) of egg yolk liquid decreased with the increase of heat treatment temperature, and the average particle size of the emulsion system formed increased. Under the same heat treatment condition, the EAI and emulsion stability index (ESI) of the modified egg yolk liquid were significantly higher than those of its unmodified counterpart (P < 0.05), and the particle size of the emulsion system formed with the modified egg yolk liquid decreased significantly, and the distribution of particle sizes was closer to the normal distribution. Raman spectral analysis showed that the secondary structure of proteins in the modified yolk liquid changed after heat treatment. With increasing heat treatment temperature up to 65 ℃, the relative content of α-helix structure increased significantly and the relative content of random coil structure decreased markedly (P < 0.05). Meanwhile, tryptophan and tyrosine residues and aliphatic hydrophobic groups were more exposed to the outside of protein molecules than the unmodified one. Partial least squares (PLS) was used to establish a model for describing the emulsifying properties of egg yolk liquid based on the Raman spectral data. It was found that changes in the conformation and secondary structure of proteins (especially low density lipoprotein) in egg yolk liquid had the greatest influence on the emulsifying properties of egg yolk liquid.

Key words: egg yolk liquid, enzymatic modification, emulsifying properties, Raman spectroscopy, heat treatment

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