Fourier transform Raman and infrared spectroscopy of pectins
ABSTRACT The FT-Raman and FT-IR spectra of polygalacturonic (pectic) acid, potassium pectate and its derivatives, as well as commercial citrus and sugar beet pectins were measured and interpreted. Methyl and acetyl esters of potassium pectate derivatives have several characteristic Raman and IR bands that allow both this groups to be distinguished. The very intense Raman band at 857 cm−1 is sensitive to the state of uronic carboxyls and to O-acetylation. The wavenumber of this band decreases with methylation (min. 850 cm−1) and increases with acetylation (max. 862 cm−1). The acetylation of potassium pectate, as well as its acetylation together with methylation, causes drastic changes in the Raman spectra in the region below 700 cm−1. Sugar beet pectin, but not citrus pectin, showed Raman bands at 1633 and 1602 cm−1 and IR band at 1518 cm−1. All these bands rise from feruloyl groups and can be used for identification of pectins containing feruloyl groups.
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ABSTRACT: The primary cell wall of fruits and vegetables is a structure mainly composed of polysaccharides (pectins, hemicelluloses, cellulose). Polysaccharides are assembled into a network and linked together. It is thought that the percentage of components and of plant cell wall has an important influence on mechanical properties of fruits and vegetables.Plant Methods 01/2014; 10:14. · 2.67 Impact Factor
Dataset: acta biomaterilia[Show abstract] [Hide abstract]
ABSTRACT: The aim of this work is to develop novel organic–inorganic hybrid beads for colonic drug delivery. For this purpose, calcium pectinate beads with theophylline are prepared by a cross-linking reaction between amidated low-methoxyl pectin and calcium ions. The beads are then covered with silica, starting from tetraethyoxysilane (TEOS), by a sol–gel process. The influence of TEOS concentration (0.25, 0.50, 0.75 and 1.00 M) during the process is studied in order to modulate the thickness of the silica layer around the pectinate beads and thus to control the drug release. The interactions between the silica coating and the organic beads are weak according to the physicochemical characterizations. A good correlation between physicochemical and in-vitro dissolution tests is observed. At concentrations of TEOS beyond 0.25 M, the silica layer is thick enough to act as a barrier to water uptake and to reduce the swelling ratio of the beads. The drug release is also delayed. Silica-coated pectinate beads are promising candidates for sustained drug delivery systems.