The extraction, structure, and gelling properties of hybrid galactan from the red alga Furcellaria lumbricalis (Baltic Sea, Estonia)
Autor: | Rando Tuvikene, Tõnis Pehk, Enn Mellikov, Andres Kollist, Tiiu Kailas, Olga Volobujeva, Marju Robal, Kalle Truus, Merike Vaher |
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Rok vydání: | 2009 |
Předmět: |
chemistry.chemical_classification
Chromatography Magnesium Extraction (chemistry) chemistry.chemical_element Plant Science Polymer Aquatic Science Galactan Cryofixation Gel permeation chromatography chemistry.chemical_compound chemistry Molar mass distribution Fourier transform infrared spectroscopy |
Zdroj: | Journal of Applied Phycology. 22:51-63 |
ISSN: | 1573-5176 0921-8971 |
Popis: | The structure and composition of galactan from Furcellaria lumbricalis (furcellaran) were investigated in connection with rheological specificities, gel structure, and extraction conditions. The polysaccharide was characterized by 13C nuclear magnetic resonance (13C-NMR) and Fourier transform infrared spectroscopy, inductively coupled plasma-optical emission spectrometry, electrothermal atomization atomic absorption spectrometry, and gel permeation chromatography methods. The microstructure of polymer gels was studied using a cryofixation method in combination with freeze-drying and scanning electron microscopy (SEM) techniques. The undersulfated furcellaran backbone consists mainly of 3,6-anhydro-d-galactose (28.5–30.1%) and galactose residues, the latter being partly sulfated in positions 4 and 6, which give rise to some specific properties of the gel. Also, residues of 6-O-methyl-d-galactose as a minor component are found to be present. The water-extracted furcellaran with the average molecular weight about 290 kDa is rich in nitrogen, calcium, magnesium, and potassium, while the sodium content is rather low. The low sulfur content (5.3%) and 13C-NMR spectra refer to an undersulfated nature of this galactan. The extraction of seaweeds in low concentration alkaline solutions (instead of water) leads to a significant increase of the minimum size of the galactan particles and the value of gel strength (more than 12 times for Rb-containing gels). The properties of the gel are dependent on specific tentacle-like structure units present in furcellaran gels established by a high-resolution SEM. |
Databáze: | OpenAIRE |
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