KU Leuven, Department of Microbial and Molecular Systems (M(2)S), Laboratory of Food Technology, Kasteelpark Arenberg 22 Box 2457, 3001 Heverlee, Belgium.
KU Leuven, Department of Microbial and Molecular Systems (M(2)S), Laboratory of Food Technology, Kasteelpark Arenberg 22 Box 2457, 3001 Heverlee, Belgium.
Food Res Int. 2021 Feb;140:110062. doi: 10.1016/j.foodres.2020.110062. Epub 2020 Dec 24.
For the first time, a model system approach was combined with H NMR fingerprinting in studying non-enzymatic browning (NEB) of pasteurized shelf-stable orange juice during storage. Various NEB precursors were used individually or in combinations to formulate simple or complex model systems, respectively, in citric acid buffer. Based on orange juice composition, ascorbic acid, sugars (sucrose, glucose and fructose) and amino acids (proline, arginine, asparagine, aspartic acid, serine and glutamic acid) were selected as the precursors for the model systems. After pasteurization and during subsequent accelerated storage (42 °C, 16 weeks) the model systems displayed a three-phase browning development. The initial browning phase was mainly the result of ascorbic acid degradation especially in the presence of amino acids and sugars. In the later phases, the contribution of reactions of sugars and amino acids to browning became apparent. The application of H NMR fingerprinting on a simple model system containing ascorbic acid revealed that its degradation pathway to intermediates such as xylonic acid, acetic acid and erythrulose was responsible for the major changes during storage. When this model system was complexed by inclusion of sugars and amino acids, the hydrolysis of sucrose to glucose and fructose was identified as the main reaction leading to differences in the samples throughout storage. These three sugars dominated the NMR spectra of the samples, overshadowing several important compounds for NEB such as ascorbic acid and its degradation products. Other more advanced NMR experiments such as two-dimensional NMR analyses should be applied in future research to identify unknown compounds from NEB reactions.
首次将模型系统方法与 H NMR 指纹图谱相结合，研究巴氏杀菌的货架稳定橙汁在储存过程中的非酶褐变（NEB）。分别使用各种 NEB 前体单独或组合来配制柠檬酸缓冲液中的简单或复杂模型系统。基于橙汁的组成，选择抗坏血酸、糖（蔗糖、葡萄糖和果糖）和氨基酸（脯氨酸、精氨酸、天冬酰胺、天冬氨酸、丝氨酸和谷氨酸）作为模型系统的前体。巴氏杀菌后，在随后的加速储存（42°C，16 周）过程中，模型系统显示出三相褐变发展。初始褐变阶段主要是抗坏血酸降解的结果，特别是在存在氨基酸和糖的情况下。在后期阶段，糖和氨基酸反应对褐变的贡献变得明显。H NMR 指纹图谱在含有抗坏血酸的简单模型系统中的应用表明，其降解途径中间体如木糖醇酸、乙酸和赤藓醇是储存过程中主要变化的原因。当这个模型系统通过包含糖和氨基酸的复合物化时，蔗糖水解为葡萄糖和果糖被确定为导致储存过程中样品差异的主要反应。这三种糖主导了样品的 NMR 光谱，掩盖了 NEB 中几个重要的化合物，如抗坏血酸及其降解产物。在未来的研究中，应该应用其他更先进的 NMR 实验，如二维 NMR 分析，以鉴定来自 NEB 反应的未知化合物。
