Non-catalytic synthesis of food components in subcritical water

在100-374℃和高压下保持液态的水称为亚临界水。在亚临界水中，H^+和OH^-的离子积比在环境水中的离子积高约1000倍。使非催化反应在亚临界水中进行。非催化反应有利于地球环境，有利于构建良好的食品加工体系。因此，本论文研究了亚临界水中非催化反应合成食品成分的方法。首先，研究了亚临界水中单糖水解生成5-羟基-2-甲基糠醛（HMF）的反应。四种单糖的水解动力学均服从威布尔方程。在果糖、半乳糖、葡萄糖和甘露糖中，果糖得到最高的HMF转化率，为48%。其次，通过LC-MS和MALDI-TOF分析产物，证实了在亚临界水（100-140℃）中不添加任何催化剂的情况下肽与二羧酸之间的缩合反应可以进行。温度越高，二羧酸中OH残基的数量越少，缩合产物的产率越高。最后，研究了亚临界水（200-260℃）中亚油酸异构化为共轭异构体的情况。延长反应时间和提高反应温度可以提高共轭亚油酸的产率。然而，即使在最大值下，转化率也非常低，为1%。在任何反应条件下，反式-10，顺式-12共轭亚油酸与顺式-9，反式-11共轭亚油酸的比例恒定为0.6。如上所述，很明显，在亚临界水中，水解、合成和异构化在没有任何催化剂添加剂的情况下进行，并且可以通过这些反应生产食品组分。

Water which is maintained in its liquid state at 100-374℃ and a high pressure is called as subcritical water. In subcritical water, the ion product of H^+ and OH^-increases about a thousand times higher than that in an ambient water. It makes non-catalytic reaction proceed in subcritical water. The non-catalytic reaction is good for environment in the earth and is available to construct a good food processing system. So, I investigated non-catalytic reaction to synthesize food components in subcritical water. Firstly, converted reaction from monosaccharides to 5-hydroxy-2-methyl furfural (HMF) was studied during hydrolysis of monosaccharides in subcritical water. The kinetics of hydrolysis of four kinds of monosaccharides obeys to Weibull equation. Fructose gave the highest conversion, 48%, of HMF among fructose, galactose, glucose, and mannose. Secondly, we confirmed that condensation reaction between a peptide and a dicarboxylic acid proceeded without any catalytic agent additive in subcritical water (100-140℃) by analysis of the product via LC-MS and MALDI-TOF. The higher temperature and the lesser number of OH residue in the dicarboxylic acids gave a higher yield of the condensation product. Finally, isomerization from linoleic acid to its conjugated isomers in subcritical water (200-260℃) was investigated. Elongation of reaction time and higher temperature gave a higher yield of the conjugated linoleic acids (CLA). However, the conversion was very low, 1%, even in the maximum value. The ratio of trans-10, cis-12 CLA to cis-9, trans-11 CLA was constantly 0.6 in any conditions of the reactions. As mentioned above, it became clear that hydrolysis, synthesis, and isomerization proceed without any catalytic reagent additive in subcritical water and that food components can be produced through these reactions.