Rheological properties of freeze-dried wheat starch/galactomannan gels

Juszczak, L.; Fortuna, T. . Dept. of Analysis and Evaluation of Food Quality; Witczak, M. . Dept. of Engineering and Machinery for Food Industry; Dymel, A. . Dept. of Analysis and Evaluation of Food Quality

Rheological properties of freeze-dried wheat starch/galactomannan gels

2004

Juszczak, L. | Fortuna, T. (Krakow Agricultural University (Poland). Dept. of Analysis and Evaluation of Food Quality) | Witczak, M. (Krakow Agricultural University (Poland). Dept. of Engineering and Machinery for Food Industry) | Dymel, A. (Krakow Agricultural University (Poland). Dept. of Analysis and Evaluation of Food Quality)

The objective of the present work was to determine the effect of galactomannans (guar and carob) on some rheological properties of freeze-dried wheat starch gels. Temperature-dependent apparent viscosity curves, flow curves, shear time-dependent apparent viscosity curves as well as mechanical spectra were plotted. On the basis of the results obtained, it can be said that both freeze-drying and gum addition to the system modify rheological properties of wheat starch pastes/gels, and that these changes depend on the type and concentration of the gum used. In the investigated systems with galactomannans, higher values of apparent viscosity were observed along with increasing temperature as well as higher values of shear stress in the flow time, as compared to native starch. It should be stressed, however, that the guar gum system was characterised by higher viscosity values than that with carob gum. The presence of particular gums in the systems modified also viscoelastic properties of gels obtained, depending on the gum used and its concentration

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