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Effects of Phosphate Salts on the pH Values and Rapid Visco Analyser (RVA) Pasting Parameters of Wheat Flour Suspensions

¹Permanent address: Department of Food Science and Technology, Anhui Agricultural University, Hefei, China. ²Wheat Marketing Center, Inc., 1200 NW Naito Parkway, Suite 230, Portland, OR 97209. ³Corresponding author. Phone: (503) 295-0823. Fax: (503) 295-2735. E-mail: ghou@wmcinc.org

Changes in pH and pasting properties of instant-noodle formula dry-mix suspensions containing each of 12 phosphate salts were investigated. The pH values of solutions alone and then solution and flour suspensions decreased as the level of phosphate salts increased, except that of trisodium phosphate, which increased the pH value. The changes in the Rapid Visco Analyser (RVA) pasting parameters of instant-noodle formula suspensions were not consistent with the respective changes in pH, but the change trends of the RVA parameters for the two different wheat flours (hard red winter and soft white wheat) were similar. Five of the phosphate salts gradually increased the RVA peak viscosity (PV) as phosphate concentration increased. Seven other phosphate salts increased the PV at 0.05% and then decreased PV as the phosphate concentration increased. The change in trough viscosity owing to phosphate salt and concentration was similar to that of PV. The final viscosity (FV) gradually declined, to varying degrees, as the phosphate concentration increased for some of the phosphate salts. However, seven of the phosphate salts caused slight increases in FV as their concentrations increased. The response of starch gelatinization and pasting behavior, as measured by RVA, indicated that phosphate salts exert an influence on starch during heating in water. Because RVA parameters have been linked to instant-noodle processing and textural properties, phosphate salt identity and concentration can likely be manipulated to affect end-product quality.