Low methoxyl pectin gelation under alkaline conditions and its rheological properties: Using NaOH as a pH regulator
Low methoxyl pectin gelation under alkaline conditions and its rheological properties: Using NaOH as a pH regulator
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DOI：
10.1016/j.foodhyd.2017.12.006
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发表时间：
2018-06-01
影响因子：
10.7
通讯作者：
Guo, Yurong
中科院分区：
文献类型：
--
作者：
Yang, Xi;Nisar, Tanzeela;Guo, Yurong
采用NaOH溶液调节低甲氧基果胶（LMP）分散液（1%，w/v）的pH，在较宽的pH范围（3.5-9.5）内制备LMP凝胶。探讨了pH值对LMP成胶机理的影响，并对凝胶的流变性能进行了研究。结果表明，当pH从3.5增加到8.5时，凝胶强度和凝胶速率增加，这是由于解离的羧基的量增加。然而，当pH增加到9.5时，由β-消除引起的果胶分子量的降低导致凝胶强度和胶凝速率的降低。此外，Ca ~（2+）的掺入不仅降低了果胶的热分解速率，而且降低了果胶的结晶度。环境扫描电子显微镜（ESEM）和热重/微分热重（TG/DTG）分析表明，pH值为8.5的凝胶具有最致密的微观结构和最高的热稳定性。总体而言，研究首次证明了宽pH范围对LMP凝胶化的影响，特别是在碱性条件下。它可能会提供一个洞察LMP应用于食品和生物医学领域。(C)2017爱思唯尔有限公司版权所有。
In this study, NaOH solution was used to adjust the pH of low methoxyl pectin (LMP) dispersions (1%, w/v), and LMP gels were prepared in a wide pH range (3.5-9.5). Then, the effects of pH on LMP gelation mechanism were explored and the rheological properties of the gels were investigated. The results suggested that when the pH was increased from 3.5 to 8.5, the gel strength and gelling rate were increased, due to an increased amount of dissociated carboxylic groups. When the pH was increased to 9.5, however, the decreasing molecular weight of the pectin, caused by beta-elimination, resulted in the decrease of the gel strength and gelling rate. Moreover, the incorporation of Ca2+ into the pectin reduced not only the thermal decomposition rate of the pectin but also its crystalline degree. Compared to the other gels, the gel at pH 8.5 had the most compact microstructure and the highest thermal stability, which were indicated by Environmental Scanning Electron Microscope (ESEM) and TG/DTG analyses, respectively. Overall, the investigation for the first time demonstrated the effects of a wide pH range on LMP gelation, especially under alkaline conditions. It may provide an insight into the application of LMP to food and biomedical fields. (C) 2017 Elsevier Ltd. All rights reserved.