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Measuring Oxidative Gelation of Aqueous Flour Suspensions Using the Rapid Visco Analyzer

¹Department of Food Science and Technology, Oregon State University, Corvallis OR, U.S.A. ²Department of Crop and Soil Science, Oregon State University, Corvallis OR, U.S.A. ³Corresponding author. Department of Crop and Soil Science, Oregon State University, 107 Crop Science, Corvallis, OR, U.S.A. Phone: (541) 737-9149. E-mail: andrew.ross@oregonstate.edu ⁴ADBWheat Consultancy, Moscow ID, U.S.A. ⁵USDA Western Wheat Quality Laboratory, Pullman, WA, U.S.A.

The Rapid Visco Analyzer (RVA) was investigated as a tool to measure oxidative gelation capacity (OGC) of aqueous wheat flour suspensions. One club wheat patent flour was used to determine optimal hydration time, and 33 straight-grade flours (representing 12 hard and 21 soft varieties) were used to observe varietal differences in OGC. A 33.3% w/w flour–water suspension was tested in the RVA at 30°C and 160 rpm for 1 min to establish the flour–water baseline viscosity, and then 65 μL of 3% H₂O₂ was added and the viscosity of the suspension measured at 160 rpm for a further 5 min. Flour from the club wheat showed that 20 min of prehydration was needed to observe full OGC potential. For the 33 straight-grade flours, final RVA water baseline viscosity was correlated with Bostwick Consistometer (BC) flow (r = −0.93, P ≤ 0.01), and RVA H₂O₂ peak viscosity was correlated with H₂O₂ BC flow (r = –0.81, P ≤ 0.01). The RVA was able to differentiate H₂O₂-reactive from nonreactive flours. The RVA can observe phenomena not observable with the BC method (e.g., viscosity reduction over time at constant shear rate), which can provide potentially valuable additional information about the nature of OGC in wheat flour suspensions.