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Rheoligical stability of waxy wheat flour and its potential as a unique freeze-thaw stable ingredient
R. KOWALSKI (1), A. Meldrum (2), S. Wang (1), S. Constantinescu (2), H. Joyner (2), C. Morris (3), G. Ganjyal (1). (1) Washington State University, Pullman, WA, U.S.A.; (2) University of Idaho, Moscow, ID, U.S.A.; (3) USDA, Pullman, WA, U.S.A.

Frozen and shelf stable foods can undergo significant variation in temperature from production, to when the consumer uses the product. Maintaining consistent food quality through these temperature changes as the food goes through freeze-thaw cycles is critical to consumer acceptance. Waxy wheat could provide a solution to this persistent problem. In an effort to develop a solution, rheological properties of multiple waxy wheat flour varieties were analyzed before and after 10 freeze-thaw cycles between 25oC and -20oC and compared with normal wheat flour varieties. It was hypothesized that the properties of the waxy wheat flours would remain the same even after subjecting them to the freeze-thaw cycles. Herschel-Bulkely models as well as storage (G’) and loss (G”) moduli across strain and frequency were identified for gelatinized flour solutions before and after the freeze-thaw cycles using a parallel plate rheometer. All of the waxy wheat flour pastes exhibited lower viscosities than the normal flour pastes.  The viscosity values remained constant after freeze-thaw cycles for the waxy flours, while the normal flours exhibited a significant drop in viscosity. It was also found that the storage and loss moduli for the waxy wheat varieties was stable at strain rates of over 10%, both before and after freeze-thaw cycling with no significant changes. The rheological results were also compared to differential scanning calorimetry (DSC) results for initial gelatinization and retrogradation. The normal flours exhibited significantly larger retrogradation enthalpies than the waxy wheat flours in all cases, with some of the waxy wheat varieties exhibiting no significant retrogradation. Overall, the data suggests that the rheological properties of waxy wheat flour change very little through the freeze-thaw cycles thus offering the solution as a natural freeze-thaw stabilizer.

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