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 E_a1 was 35.94 kJ/mol and the reducing sugar degradation activation energy E_a2 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.