Optimization of Adsorption of Tea Polyphenols into Oat β-Glucan Using Response Surface Methodology

Information on interactions between oat β-glucan and tea polyphenols (TP) is not available in the published literatures. Equilibrium dialysis was applied to determine the adsorption of TP into β-glucan, and response surface methodology (RSM) was employed to optimize the absorbing variables (pH, temperature, and phosphate buffered saline (PBS) buffer concentration). The equilibrium data at constant temperature were fitted with the Langmuir, Freundlich, and Redlich-Peterson models. The results showed that the Freundlich model was the best method to describe the experimental data. Parabolic curves were obtained for pH and temperature. In terms of adsorption capacity, factors including temperature, pH/temperature, and buffer concentration/temperature had the greatest influence on the response. The highest adsorption capacity of TP into β-glucan was 134.55 μg mg−1 at the following optimized conditions: pH 5.56, PBS buffer concentration 0.13 M, and temperature 40 °C. No significant differences (p > 0.05) between the experimental and predicted values confirmed the adequacy of the response surface equations.