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Water Distribution in Frozen Lean Wheat Doughs

¹VTT, Biotechnology and Food Research, P.O. Box 1500, FIN-02044 VTT, Finland. ²Corresponding author. Phone: +358-9-456 5215. Fax: +358-9-455 2103. E-mail: janne.rasanen@vtt.fi ³University of Nottingham, Department of Applied Biochemistry and Food Science, Sutton Bonington Campus, Loughborough, Leics. LE11 5RD, UK. ⁴Department of Chemistry, Laboratory of Radiochemistry, P.O. Box 55, FIN-00014 University of Helsinki, Finland

Frozen storage increased the amount of liquid phase and decreased the storage modulus of water-flour mixtures. The liquid phase was studied by ultracentrifugation. The most significant change occurred during the first week of storage. The negative effects of ice crystals could be controlled by reducing the water content, which was seen as smaller amounts of liquid phase and higher dough rigidity after frozen storage (G′ values). Reduced water content also prevented an increase in the self-diffusion coefficient during frozen storage (¹H NMR studies). Prefermented frozen doughs were examined under different conditions: with and without Skimo (additive from Puratos, Belgium), prefermentation time of 25 or 40 min, and reduced water content. The results obtained with autoradiographic method correlated best with the baking results and showed that S-kimo and shorter prefermentation time improve the water distribution of frozen prefermented doughs. Doughs contained small ice crystals after frozen storage and there were no large water patches in thawed doughs. Reduced water content and exclusion of S-kimo decreased the liquid phase of fermented doughs and increased dough rigidity. The baking properties of frozen prefermented doughs were better predicted by large deformation rheology (expansion potential of samples during oscillation). In general, flour quality had an obvious effect on the parameters. There was no correlation between the rheological properties and the values of liquid phase, but in most cases a high correlation between the total water content and rheological properties was observed.