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Effect of flour aging on oxidative gelation and absorption characteristics of soft-wheat flour
J. E. MATTSON (1), O. Miranda-Garcia (1), A. S. Ross (1), T. Kongraksawech (1), A. D. Bettge (2). (1) Oregon State University, Corvallis, OR, U.S.A.; (2) ADB Wheat Consulting, Moscow, ID, U.S.A.

Oxidative gelation is reputed to be an important trait in soft-wheat technology. A previous study in our labs indicated genotypic differences in the oxidative gelation capacity (OGC) of soft-wheat flours. As flour can experience oxidation during storage our objective was to observe OGC and flour absorption capacity after defined periods of both grain and flour storage. Our aim was to generate preliminary data that might determine whether OGC was “hard-wired” into kernel composition or whether it might be a result of oxidation during grain or flour storage. Grain of 4 soft-wheat cultivars with divergent OGC was milled to flour at 0, 3, 6, 13, and 24 weeks after harvest. Flour was tested at 0, 1, 3, 6, 13, 27, and 62 days after milling for all milling dates. OGC was quantified using an RVA-based method that observes the viscosity of a flour/water suspension after addition of hydrogen peroxide. SRC capacity was observed using AACC-I Approved Method 56-11. 3-way ANOVA indicated significant differences (p < 0.05) in OGC between cultivars and between milling dates. The differences between milling dates did not appear to be systematic. ANOVA also showed significant (p < 0.05) increases in OGC after milling. Increased OGC was observed for all 4 cultivars, regardless of their initial OGC baseline (high or low). ANOVA also indicated that SRC values changed with flour storage: water and sucrose SRCs showed small but significant (p < 0.05) increases during flour storage. Carbonate and lactic acid SRCs had significantly (p < 0.05) decreased values across the 62 days of flour storage. Conclusions: although milling time after harvest, storage time after milling, and genotype all affect OGC of flour, genotypic differences were observed from the beginning of the storage period suggesting that OGC is genetically determined.

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