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.
- SourceAvailable from: Wei Wang
- "microspectroscopy. Because strong hydrogen-bonded -OH bands in the range of 4000–2995 cm −1 were commonly observed in all spectra (Oh et al. 2005), the peak band at 3345 cm −1 was generally assigned to -OH (Synytsya et al. 2003). The quantity of these functional groups could be semiquantitatively reflected by the photoacoustic intensity, which is generated by converting the absorbed modulated radiation to heat (Zhang et al. 2009). "
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- "The data of the X matrix were mean-centred and variance-scaled, and the Y data were only mean-centred. The maximum number of components used for the PLS analysis was seven and the algorithm used Table 3 Assignment of bands in the infrared spectra of cell wall material from apple parenchyma (Fellah et al., 2009; Kačurakova et al., 2000; Kačurakova & Wilson, 2001; Kondo & Sawatari, 1996; Sene et al., 2004; Synytsya et al., 2003; Wellner, Kačurakova, Malovikova, Wilson, & Belton, 1998; Zhbankov et al., 2002). "
ABSTRACT: The aim of this work was to quantitatively and qualitatively determine the composition of the cell wall material from apples during development by means of Fourier transform infrared (FT-IR) spectroscopy. The FT-IR region of 1500–800 cm−1, containing characteristic bands for galacturonic acid, hemicellulose and cellulose, was examined using principal component analysis (PCA), k-means clustering and partial least squares (PLS). The samples were differentiated by development stage and cultivar using PCA and k-means clustering. PLS calibration models for galacturonic acid, hemicellulose and cellulose content from FT-IR spectra were developed and validated with the reference data. PLS models were tested using the root-mean-square errors of cross-validation for contents of galacturonic acid, hemicellulose and cellulose which was 8.30 mg/g, 4.08% and 1.74%, respectively. It was proven that FT-IR spectroscopy combined with chemometric methods has potential for fast and reliable determination of the main constituents of fruit cell walls.Carbohydrate Polymers 01/2015; 115:93–103. DOI:10.1016/j.carbpol.2014.08.039 · 3.92 Impact Factor
- "The bands observed at 1667, 1566 and 1444 cm -1 correspond to primary amide groups, NH 2 from amide function and OCH 2 deformation of methyl ester, respectively. The region of 1200-1000 cm À1 , which contains skeletal C–O and C–C vibration bands of glycosidic bonds and a pyranoid ring, are considered to be the ''fingerprint'' region that is specific to a polysaccharide compound . When the TEOS concentration is increased, no significant changes in the wavenumbers of pectin functional groups (primary amide and methyl ester groups) are observed. "
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.