%0 Journal Article %1 DRAGET1993 %A DRAGET, K. I. %A SIMENSEN, M. K. %A ONSOYEN, E. %A SMIDSROD, O. %C SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS %D 1993 %I KLUWER ACADEMIC PUBL %J Hydrobiologia %K ; ;; BREAKING CA-ALGINATE; GEL METHODS; MOLECULAR RHEOLOGICAL STRENGTH; WEIGHT [ISI:] rheology; state %P 563 -- 569 %T GEL STRENGTH OF CA-LIMITED ALGINATE GELS MADE IN-SITU %V 261 %X The gel strengths of Ca-alginate gels made in situ with different degree of cross-linking were determined by adapting three different methods: FIRA Jelly Tester, initial deformation (Youngs modulus, E) with a Stevens LFRA Texture Analyzer, and dynamic measurements with a Bohlin VOR Rheometer (dynamic storage modulus, G'). The results showed that there were relatively large differences in absolute values, but that the deviations diminished when the results were expressed as relative gel strengths. The deviations of the Youngs modulus (E) from G' increased with decreasing gel strength. Only dynamic measurements were suitable for quantifying low gel strengths. The gel strength and the breaking point were also measured as a function of the molecular weight of alginates isolated from stipes of Laminaria hyperborea. In the present Ca limited system, both the gel strength and the breaking point showed a marked increase with increasing molecular weight (Mw) up to 320-340 kD. This is considerably higher than with gels made by dialysis ('Ca saturated'), where the gel strength becomes independent oil molecular weight around 100 kD. These results may have an impact on applications of alginate gels where the source of Ca crosslinking ions is limited.

@article{DRAGET1993, __markedentry = {[phpts:6]}, abstract = {The gel strengths of Ca-alginate gels made in situ with different degree of cross-linking were determined by adapting three different methods: FIRA Jelly Tester, initial deformation (Youngs modulus, E) with a Stevens LFRA Texture Analyzer, and dynamic measurements with a Bohlin VOR Rheometer (dynamic storage modulus, G'). The results showed that there were relatively large differences in absolute values, but that the deviations diminished when the results were expressed as relative gel strengths. The deviations of the Youngs modulus (E) from G' increased with decreasing gel strength. Only dynamic measurements were suitable for quantifying low gel strengths. The gel strength and the breaking point were also measured as a function of the molecular weight of alginates isolated from stipes of Laminaria hyperborea. In the present Ca limited system, both the gel strength and the breaking point showed a marked increase with increasing molecular weight (Mw) up to 320-340 kD. This is considerably higher than with gels made by dialysis ('Ca saturated'), where the gel strength becomes independent oil molecular weight around 100 kD. These results may have an impact on applications of alginate gels where the source of Ca crosslinking ions is limited.}, added-at = {2011-11-04T13:47:04.000+0100}, address = {SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS}, author = {DRAGET, K. I. and SIMENSEN, M. K. and ONSOYEN, E. and SMIDSROD, O.}, authoraddress = {UNIV TRONDHEIM,NORWEGIAN INST TECHNOL,DIV BIOTECHNOL,NORWEGIAN BIOPOLYMER LAB,N-7034 TRONDHEIM,NORWAY.}, biburl = {https://www.bibsonomy.org/bibtex/2254671ce2dd577c3422be96682d49004/pawelsikorski}, citedref = {CAMPBELL LE, 1938, J SOC CHEM IND LOND, V57, P413 ; COTTRELL IW, 1980, HDB WATER SOLUBLE GU ; DRAGET KI, 1989, APPL MICROBIOL BIOT, V31, P79 ; DRAGET KI, 1991, CARBOHYD POLYM, V14, P159 ; FLORY PJ, 1953, PRINCIPLES POLYM CHE, P459 ; GRASDALEN H, 1979, CARBOHYD RES, V56, C11 ; GRASDALEN H, 1983, CARBOHYD RES, V118, P255 ; KOHN R, 1972, ACTA CHEM SCAND, V26, P2455 ; MARTINSEN A, 1991, CARBOHYD POLYM, V15, P171 ; MITCHELL JR, 1976, J TEXTURE STUD, V7, P313 ; MITCHELL JR, 1980, J TEXTURE STUD, V11, P315 ; SKJAKBRAEK G, 1986, INT J BIOL MACROMOL, V8, P330 ; SMIDSROD O, 1972, ACTA CHEM SCAND, V26, P2063 ; SMIDSROD O, 1972, ACTA CHEM SCAND, V26, P79 ; SMIDSROD O, 1972, ACTA CHEM SCAND, V66, P79 ; SMIDSROD O, 1990, TIBTECH, V5, P335 ; STOKKE BT, 1991, MACROMOLECULES, V24, P4637}, interhash = {a8e8455dfa16fcbb964314cc23e8202b}, intrahash = {254671ce2dd577c3422be96682d49004}, isifile-dt = {Article}, isifile-ga = {LR168}, isifile-j9 = {HYDROBIOLOGIA}, isifile-nr = {17}, isifile-pi = {DORDRECHT}, isifile-sc = {Marine & Freshwater Biology}, isifile-tc = {2}, issn = {0018-8158}, journal = {Hydrobiologia}, keywords = {; ;; BREAKING CA-ALGINATE; GEL METHODS; MOLECULAR RHEOLOGICAL STRENGTH; WEIGHT [ISI:] rheology; state}, language = {English}, month = {JUN 18}, owner = {phpts}, pages = {563 -- 569}, publisher = {KLUWER ACADEMIC PUBL}, size = {7 p.}, sourceid = {ISI:A1993LR16800075}, timestamp = {2011-11-04T13:47:09.000+0100}, title = {GEL STRENGTH OF CA-LIMITED ALGINATE GELS MADE IN-SITU}, volume = 261, year = 1993 }