Programa de Pós-Graduação em Engenharia de Alimentos, Departamento de Engenharia Química, Universidade Federal do Paraná, CEP 81531-980, Curitiba, PR, Brasil.
Department of Food Chemistry and Technology, Teagasc Food Research Centre, Ashtown, Dublin 15, Ireland.
Int J Biol Macromol. 2018 Apr 1;109:784-792. doi: 10.1016/j.ijbiomac.2017.11.060. Epub 2017 Nov 11.
The present study aimed to investigate the physical, structural and rheological modifications caused by the chemical modification process of citrus pectin. Therefore, three commercial citrus pectins with different degree of esterification were chemically modified by sequential alkali and acidic hydrolytic process to produce modified citrus pectins (MCP) with special properties. The molar mass (M), degree of esterification (DE), monosaccharide composition, C NMR spectra, homogeneity, morphology (SEM) and rheological behavior of both native and modified citrus pectins (MCP) were investigated. The chemical modification reduced the acid uronic content (up to 28.3%) and molar mass (up to 29.98%), however, showed little influence on the degree of esterification of native pectins. Modified citrus pectins presented higher amounts of neutral monosaccharides, mainly galactose, arabinose and rhamnose, typical of the Ramnogalacturonana-I (RG-I) region. Rheological tests indicated that the native and modified citrus pectins presented pseudoplastic behavior, however, the MCP samples were less viscous, compared to the native ones. Modified samples presented better dissolution in water and less strong gels, with good stability during oscillatory shearing at 25°C. This study aims to better understand the implications that chemical modifications may impose on the structure of citrus pectins.
本研究旨在探讨柑橘果胶化学修饰过程引起的物理、结构和流变改性。因此，通过顺序碱和酸性水解过程对三种具有不同酯化程度的商业柑橘果胶进行化学修饰，以生产具有特殊性质的改性柑橘果胶（MCP）。对天然和改性柑橘果胶（MCP）的摩尔质量（M）、酯化度（DE）、单糖组成、C NMR 光谱、均一性、形态（SEM）和流变行为进行了研究。化学修饰降低了酸醛酸含量（高达 28.3%）和摩尔质量（高达 29.98%），但对天然果胶的酯化度影响很小。改性柑橘果胶含有更多的中性单糖，主要是半乳糖、阿拉伯糖和鼠李糖，这是 Ramnogalacturonana-I（RG-I）区域的典型特征。流变学测试表明，天然和改性柑橘果胶均表现出假塑性，但与天然果胶相比，MCP 样品的粘性更小。改性样品在水中的溶解性能更好，凝胶强度更低，在 25°C 下的振荡剪切过程中具有良好的稳定性。本研究旨在更好地理解化学修饰可能对柑橘果胶结构造成的影响。
