School of Chemistry and Environmental Science, Guangdong Ocean University, Zhanjiang 524088, China; School of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang 524088, China.
School of Chemistry and Environmental Science, Guangdong Ocean University, Zhanjiang 524088, China.
Food Chem. 2018 Oct 30;264:277-283. doi: 10.1016/j.foodchem.2018.04.098. Epub 2018 Apr 24.
The mechanism of the thermal degradation and the toxicity of the thermal degradation products of agar were studied using TG/DTA, Fourier-transform infrared spectroscopy and pyrolysis gas chromatography/mass spectrometry. It was found that the thermal degradation of agar is a single-step reaction, the thermal degradation temperature (T, T, T) increases with increasing gel strength (P) and the influence of P on the thermal degradation rate is modest. The thermal degradation of agar is an exothermic reaction, and the activation energy of the reaction increases with increasing P. In the thermal degradation, agar is first decomposed into 3,6-anhydropyran galactopyranose and galactopyranose, then 3,6-anhydropyran galactopyranose, and finally furyl hydroxymethyl ketone, through loop opening, dehydration and hydrogen transfer. Galactopyranose follows three degradation pathways, and its final degradation products are 3,4-atrosan, d-allose, furfural and 5-(hydroxymethyl)-2-furancarboxaldehyde. Of the degradation products, furyl hydroxymethyl ketone, furfural, and 5-(hydroxymethyl)-2-furancarboxaldehyde show some toxicity to humans.
使用 TG/DTA、傅里叶变换红外光谱和热解气相色谱/质谱法研究了琼脂的热降解机制和热降解产物的毒性。结果表明，琼脂的热降解是一个单步反应，热降解温度（T、T、T）随凝胶强度（P）的增加而升高，而 P 对热降解速率的影响不大。琼脂的热降解是一个放热反应，反应的活化能随 P 的增加而增加。在热降解过程中，琼脂首先分解为 3,6-脱水吡喃半乳糖吡喃糖和半乳糖吡喃糖，然后通过开环、脱水和氢转移，3,6-脱水吡喃半乳糖吡喃糖最终分解为糠基羟甲基酮。半乳糖吡喃糖遵循三条降解途径，其最终降解产物为 3,4-阿特罗桑、D-阿洛糖、糠醛和 5-（羟甲基）-2-呋喃甲酮。在降解产物中，糠基羟甲基酮、糠醛和 5-（羟甲基）-2-呋喃甲酮对人体具有一定的毒性。
