Dept. of Physics, Univ. of Memphis, 216 Manning Hall, Memphis, TN 38152, U.S.A.
J Food Sci. 2014 Jan;79(1):C25-31. doi: 10.1111/1750-3841.12325. Epub 2013 Dec 23.
Heating powder isolated soy proteins (ISPs) in a N₂ environment produced thermally stimulated luminescence (TSL), in 2 major temperature regions, 50 to 250°C (region R1) and 250 to 350°C (region R2). In soy protein 7S fraction, strong TSL was detected in both regions with glow peak maximum (T(m)) at 150 ± 15°C and at 300 ± 10°C. Two additional satellite or shoulder peaks were detected from the ISP and 7S protein fraction within region R1 at T(m) = 90°C and T(m) = 210°C. The soy protein 11S fraction produced a broad, poorly defined TSL peak in the low-temperature region. Electron paramagnetic resonance spectroscopy data from the control ISP sample, deuterium sulfide-treated ISP, ISP stored in either N₂ or O₂, and defatted soy flour, indicated that the trapped radicals present in ISP is associated with the production of the primary TSL peak at 150 ± 15°C. Activation energies required to release the trapped charges (for luminescence to occur) are approximately 0.70, 0.78, 1.50, and 1.8 eV for TSL at Tm = 100, 150, 200, and 300°C, respectively. The reaction mechanism that leads to the release of the trapped charges for TSL to occur followed a mixed order kinetic, between 1.5 and 1.8. The frequency factor varied between 10⁷/s and 10¹⁷/s.
在氮气环境中加热分离大豆蛋白（ISP）会产生热激励发光（TSL），分为两个主要温度区域，50 至 250°C（区域 R1）和 250 至 350°C（区域 R2）。在大豆蛋白 7S 部分中，在两个区域都检测到了强烈的 TSL，发光峰最大值（T(m)）分别为 150 ± 15°C 和 300 ± 10°C。在 ISP 和 7S 蛋白部分的区域 R1 中，还检测到了两个额外的卫星峰或肩峰，T(m) = 90°C 和 T(m) = 210°C。大豆蛋白 11S 部分在低温区产生了一个宽而定义不明确的 TSL 峰。来自对照 ISP 样品、氘化硫化物处理的 ISP、储存在氮气或氧气中的 ISP 和脱脂大豆粉的电子顺磁共振波谱数据表明，存在于 ISP 中的捕获自由基与在 150 ± 15°C 处产生的主要 TSL 峰有关。释放捕获电荷（发光发生）所需的活化能分别约为 0.70、0.78、1.50 和 1.8 eV，用于 TSL 在 Tm = 100、150、200 和 300°C 时。导致 TSL 发生的捕获电荷释放的反应机制遵循混合阶动力学，介于 1.5 和 1.8 之间。频率因子在 10⁷/s 和 10¹⁷/s 之间变化。
