Jansens Koen J A, Brijs Kristof, Stetefeld Jörg, Delcour Jan A, Scanlon Martin G
Laboratory of Food Chemistry and Biochemistry, Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven Kasteelpark Arenberg 20, B-3001 Leuven, Belgium.
Department of Chemistry, University of Manitoba, Winnipeg, Canada R2T 2N2.
ACS Omega. 2017 Aug 17;2(8):4612-4620. doi: 10.1021/acsomega.7b00366. eCollection 2017 Aug 31.
Thermal processing conditions, pH, and salt content affect the formation of egg white ovalbumin amyloid, which was investigated using high-precision measurements of ultrasonic velocity and attenuation. These were related to fluorescence and particle size measurements. Fluorescence changes indicated the formation of amyloid-like aggregates that was enhanced by increasing time-temperature treatments. The ultrasonic velocity of ovalbumin after heating at neutral pH (60 min at 70 or 80 °C) was lower than that of unheated ovalbumin, whereas the attenuation was higher. The decrease in the velocity represents increased compressibility associated with a change in the compactness of the protein, whereas changes in attenuation are due to protein conformational changes. Heating ramp studies revealed transitions at approximately 58 and 73 °C. During heating at a constant temperature, the ultrasonic velocity decreased slowly with increasing heating time, indicating an increase in ovalbumin compressibility. It is suggested that the obtained amyloid-like ovalbumin aggregates contain a compact core surrounded by loosely packed protein segments.
热加工条件、pH值和盐含量会影响蛋清卵清蛋白淀粉样蛋白的形成，对此通过高精度测量超声速度和衰减进行了研究。这些测量结果与荧光和粒径测量相关。荧光变化表明随着时间-温度处理的增加，淀粉样聚集体的形成得到增强。在中性pH条件下加热（70或80℃加热60分钟）后，卵清蛋白的超声速度低于未加热的卵清蛋白，而衰减更高。速度的降低表示与蛋白质紧密程度变化相关的可压缩性增加，而衰减的变化是由于蛋白质构象变化。加热升温研究揭示了在约58℃和73℃时的转变。在恒温加热过程中，超声速度随着加热时间的增加而缓慢降低，表明卵清蛋白的可压缩性增加。有人提出，所获得的淀粉样卵清蛋白聚集体包含一个紧密的核心，周围是松散堆积的蛋白质片段。
