Influence of the Carboxylic Function on the Degradation of D-Galacturonic Acid and Its Polymers
Influence of the Carboxylic Function on the Degradation of D-Galacturonic Acid and Its Polymers
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DOI：
10.1021/acs.jafc.1c02388
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发表时间：
2021-08-05
影响因子：
6.1
通讯作者：
Kroh, Lothar W.
中科院分区：
文献类型：
--
作者：
Fatouros, Alexandra;Einhorn-Stoll, Ulrike;Kroh, Lothar W.
过去的研究表明，与还原糖相比，糖酸焦糖化过程中褐变的可能性较高。然而，尚未采取任何方法来阐明其化学机制。因此，本研究旨在通过测量糖醛酸热处理过程中的变旋速度和CO2的消除来阐明高褐变潜力的原因。旋光实验表明，D-半乳糖醛酸的变旋速度超过D-半乳糖近4.5倍。然而，开环速度并不是两种碳水化合物结构之间唯一不同的参数。在60℃下加热的D-半乳糖醛酸的CO2释放量测量结果显示稳定增加，48小时后，6%的降解D-半乳糖醛酸消除了CO2。在果胶加热过程中也发现了二氧化碳释放，表明热降解过程中发生了脱羧反应。假设释放二氧化碳的降解反应之一会产生α-酮戊二醛，它负责形成多种发色物质。
Past investigations have shown high browning potential during the caramelization of sugar acids in comparison to reducing sugars. However, no approaches to elucidate the chemical mechanisms have been made. Therefore, this study aims to clarify the reasons for the high browning potential by measuring the mutarotation velocity and the elimination of CO2 during the heat treatment of uronic acids. Performed polarimetric experiments show that the mutarotation velocity of D-galacturonic acid exceeds that of D-galactose by a factor of nearly 4.5. However, the ring opening velocity is not the only parameter that differs between the two carbohydrate structures. Measurements of the release of CO2 of heated D-galacturonic acid at 60 degrees C show a steady increase, and after 48 h, 6% of degraded D-galacturonic acid has eliminated CO2. CO2 release was also found during the heating of pectin, indicating a decarboxylation reaction during thermal degradation. One of the degradation reactions postulated for the release of CO2 leads to alpha-ketoglutaraldehyde, which is responsible for the formation of several chromophoric substances.