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Prediction of β-Glucan Concentration Based on Viscosity Evaluations of Raw Oat Flours from High β-Glucan and Traditional Oat Lines

¹Department of Food Science and Human Nutrition, Iowa State University, Ames, IA 50011. ²Department of Agronomy, Iowa State University, Ames, IA 50011. ³Department of Agricultural & Biosystems Engineering, Iowa State University, Ames, IA 50011. ⁴Present address: Thermo Electron Corporation, Madison, WI 53711. ⁵Corresponding author. Phone: 515-294-9688. Fax: 515-294-8181. E-mail: pjwhite@iastate.edu

Rheological properties of raw oat flour slurries were determined in experimental high β-glucan (≤7.8%) and traditional oat lines (4–5% β-glucan) grown in two consecutive years. Three different media were used to disperse oat flours: deionized water, silver nitrate solution (to inactivate endogenous enzymes), and alkali solution (to solubilize both water-soluble and water-insoluble β-glucans). Significant correlations (P < 0.05) between viscosity of slurries and β-glucan concentration obtained in either deionized water (r = 0.833), silver nitrate (r = 0.940), or alkali (r = 0.896) solutions showed that β-glucans were the main contributor to oat extract viscosity. The highest correlation was obtained in silver nitrate solution, suggesting that inactivating endogenous enzymes is important to obtain high correlations. Predictive models of oat β-glucan concentration based on the viscosity profile were developed using partial least squares (PLS) regression. Prediction of β-glucan concentration based on viscosity was most effective in the silver nitrate solution (r = 0.949, correlation coefficient of predicted vs. analyzed β-glucans) and least effective in the alkali solution (r = 0.870). These findings demonstrate that the β-glucan in oat could be predicted by measuring the viscosity of raw flours in silver nitrate solution, and this method could be used as a screening tool for selective breeding.