蛋黄水凝胶中可冻结水的同步热分析结果及其讨论

为了研究蛋白质水凝胶中水的状态,利用同步热分析仪,研究了鸡蛋中蛋黄和蒸馏水的热流量、质量随温度的变化.实验结果表明：1）在-50℃~50℃温度范围内,以10K/min的升温过程中,蛋黄和蒸馏水样品均出现了熔化现象,在测量温度范围内样品的热性质与热历史无关.2）蛋黄样品和蒸馏水的熔化峰形在测量的温度区间内,低温区重合得不是很好,但在高温区有很好的重合,说明蛋黄和蒸馏水样品的吸热行为在初始熔化时不同,在峰值以上温区内,基本一致.3）蛋黄蛋白质水凝胶中可冻结水晶粒尺寸与蒸馏水中的晶粒尺寸不同,导致了蛋黄中可冻结水与等质量的蒸馏水在熔化过程中吸收的热量不同,且蛋黄的熔化峰出现在比蒸馏水熔化峰低的温区内.4）实验经过多次反复测量,实验结果具有很好的可靠性和可重复性,表明利用DSC方法通过熔化峰的吸热量计算蛋白质水凝胶中可冻结水含量的方法存在系统误差,但偶然误差小.

The Results of the Freezing Water in Yolk Hydrogel by Simultaneous Thermal Analysis and Its Discussions

To study of water status in protein hydrogel, Simultaneous Thermal Analyzer is employed to study yolk samples and distilled samples water, and the heat flow Φ and the relative quality m/m0 changes with temperature T of which are gained. The following results are gotten after the analysis. 1） Both yolk and distilled water have the melting phenomena and absorb heat in the heating process, in the temperature range of-50℃~50℃, which in the 10K/min heating process respectively; Moreover,the experiment shows that the change of yolk is a reversible process without the thermal history. 2） The melting peaks of yolk and distilled water are significantly different at low temperature,but in the high temperature side show good similarity, however, which show that the melting mechanism of yolk and distilled water is different at the initial melting and the same above the melting peak temperature. 3） The distribution of the size of freezing water grain in the yolk protein hydrogel different from the grains distribution of the distilled water, which causes that the melting temperature of yolk is lower than distilled water＇s and absorb heat in the melting process of yolk is also different from distilled water＇s. 4）The repeatedly experiment have good reliability and repeatability, and the results show that the method according to the absorption heat of the melting peak by DSC to calculate the content of the freezing water in protein hydrogel has a systemic error, however, the accidental error of which is smaller.