Portal de Periódicos da CAPES

Fractionation and viscometric characterization of a (1→3), (1→4)-β-d-glucan from oat, and universal calibration of a high-performance size-exclusion chromatographic system by the use of fractionated β-glucans, alginates and pullulans

1991; Elsevier BV; Volume: 5; Issue: 4 Linguagem: Inglês

10.1016/s0268-005x(09)80048-9

1873-7137

Kjell M. Vårum, Anita Martinsen, Olav Smidsrød,

Food composition and properties

A polydisperse sample of mixed-linkage (1→3), (1→4)-β-D-glucans from oat aleurone was fractionated by conventional size exclusion chromatography on semipreparative columns of Sepharose CL 4B and 6B to produce fractions of low polydispersity. The fractions were characterized by their intrinsic viscosities and their number-average molecular weight. The HPSEC-chromatograms of the β-glucan fractions suggested very narrow molecular weight distributions in all fractionated samples. From knowledge of the relative weights of the fractions and by assuming that each fraction was strictly monodisperse, the weight and number-average molecular weight of the unfractionated sample of β-glucan were determined to be 71 900 and 49 000, respectively, in reasonable agreement with the number-average molecular weight determined by osmometry (55 000). The Mark-Houwink-Sakurada viscosity equation for monodisperse β-glucans was determined for samples having molecular weights from 26 × 103 to 137 × 103 g/mol as [η]=6.7×10−2M¯n0.75 (in ml/g) (20°C, 0.1 mol/dm3 NaCl). The β-glucan fractions were further characterized by high-performance size-exclusion chromatography, and compared with commercially prepared pullulan fractions of low polydispersity and alginate fractions obtained in another study in this laboratory. The validity of the universal calibration procedure was tested with the three different polysaccharides, showing the same linear relationship between hydrodynamic volume ([η] × M) and elution volume for all three polysaccharides. The commercial pullulan samples seemed well-suited for calibration purposes.