脱脂椰蓉粉亚临界水降解动力学及产物形态研究

以脱脂椰蓉为研究对象,考察了不同亚临界水降解条件对其降解过程的影响,并测定了100～200℃,不同反应时间下降解产物中还原糖的含量。采用Saeman模型对实验数据进行模拟,建立脱脂椰蓉粉亚临界水降解反应动力学方程,得到亚临界水降解动力学参数;并对降解物进行形态学分析。结果表明,Seaman模型能较好的反映脱脂椰蓉粉亚临界水降解的过程,初步降解的反应活化能E_a1为35.94 kJ/mol,还原糖降解活化能E_a2为32.12 k J/mol,指前因子K₁₀为6.50×10~2min^-1、K₂₀为3.24×10~2min^-1。该降解过程在140℃、30 min能得到温度的高还原糖产物。脱脂椰蓉粉在亚临界水中降解过程中,形态随温度、时间变化而变化,随着温度的升高原料的转化率逐渐升高,原料由固态转化为液态部分越多,水解程度越大。扫描电镜结果表明,随着降解温度的升高和降解时间的延长,脱脂椰蓉粉的纤维结构破坏越显著。

Degradation Kinetics and Product Morphology of Subcritical Water Degradation of Defatted Coconut Flour

Using the defatted coconut flour as raw material,the study investigated the influence of different subcritical water degradation conditions on the degradation process and determined the contents of reducing sugar in degradation products with different reaction times of 100 ~ 200 ℃. The model of Saeman was used to simulate the experimental data,and the kinetics equation of the subcritical water degradation reaction was established.Based on this,the kinetic parameters of subcritical water degradation and the morphological analysis of the degradation are obtained. The results showed that the Seaman model could better reflect the subcritical water degradation process of defatted coconut flour.The initial degradation energy of material Ea1 was 35.94 kJ/mol and the reducing sugar degradation activation energy Ea2 was 32.12 kJ/mol,respectively. And the pre-exponential factors K10 was 6.50 × 102 min-1,K20 was 3.24 × 102 min-1.The degradation process could obtain a high-reducing sugar product at a temperature of 140 ℃ for 30 min.During the degradation of defatted coconut powder in subcritical water,the morphology changed over temperature and time. With the temperature increasing,the conversion rate of the raw material increased gradually,the raw material also converted from the solid to the liquid,and the degree of hydrolysis was greater. The results of scanning electron microscopy showed that the fiber structure damage of defatted coconut flour was more significant with the increase of degradation temperature and the prolongation of degradation time.