28.02.2013 Views

Handbook of Size Exclusion Chromatography and Related ...

Handbook of Size Exclusion Chromatography and Related ...

Handbook of Size Exclusion Chromatography and Related ...

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

Figure 24 Wheat PA-glucan. Elution pr<strong>of</strong>iles: mass by DRI !mass ev (—†—)<br />

molar PA-glucan fractions ! mol ev (—B—). SEC system: TosoHaas guard<br />

PWH þ GMPWM þ GMPW6000 þ 5000 þ 4000 þ 3000 (150 7.5 mm); eluent,<br />

0.1 M NaCl(aq) þ 0.005 M Na 2CO 3(aq) þ NaN 3; flow rate, 0.80 mL/min; sample<br />

(injected) volume, 0.4 mL (5 mg/mL).<br />

. Rheology at increasing shear rates to determine stability <strong>of</strong> glucan/<br />

glucan aggregate systems under applied mechanical stress;<br />

. Rheology at increasing temperature to determine stability <strong>of</strong> glucan/<br />

glucan aggregate systems under applied thermal stress;<br />

. Rheology at constant shear rate <strong>and</strong> temperature program to determine<br />

disintegration behavior <strong>and</strong> reorganization capability <strong>of</strong> glucan/glucan<br />

aggregate systems; <strong>and</strong><br />

. Photon correlation spectroscopytoobtaindiffusionmobilities<strong>of</strong>glucan<br />

<strong>and</strong> glucan aggregates, that is, <strong>of</strong> coherent glucan segments, without<br />

significant destructive energy input.<br />

5.4 Bulk Properties <strong>of</strong> Starch Glucans: Rheology<br />

For investigations with respect to presence <strong>and</strong> influence <strong>of</strong> glucan aggregates,<br />

wheat starch glucans were dissolved in DMSO by stirring at elevated temperature<br />

(908C) <strong>and</strong> reflux cooling for more than 200 hours. At increasing times <strong>of</strong> this<br />

dissolution process, aliquots were taken <strong>and</strong> investigated with respect to<br />

component characteristics by means <strong>of</strong> SEC (Fig. 12) as well as with respect to<br />

bulkcharacteristics,primarilybyrheology.Firstexperimentswereperformedwith<br />

© 2004 by Marcel Dekker, Inc.

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!