Application of the rapid visco analyzer (RVA) as an effective rheological tool for measurement of beta-glucan viscosity.

摘要

Physiochemical properties of beta-glucan in oat and barley foods can affect human physiological responses. A method for continuous measurement of beta-glucan viscosity with a rapid visco analyser (RVA) was developed to overcome the complexity of common protocols based on in vitro digestion methods. Effects of several parameters on viscosity and solubility were considered. Oat cereal foods showed different RVA viscosity profiles depending on their physiochemical properties. Products high in starch exhibited a high initial viscosity that was reduced by alpha-amylase action, whereas products with low amounts of starch exhibited a slow increase in viscosity. Viscosity of all samples reached a plateau in the viscosity curve after 1-2 h, which is the key for obtaining reproducible results. Optimum digestion condition was achieved using sodium phosphate buffer (pH 6.9) and 1% beta-glucan dispersion at 37 degrees C and 160 rpm. A particle size of <0.6 mm gave more consistent viscosities than did larger particles without affecting the solubility of beta-glucan. Pancreatin and alpha-amylase concn. affected the viscosity profile by influencing the digestion rate of protein and starch in the samples, but pepsin had limited influence at pH 6.9. Highly significant Pearson correlation between the in vitro digestibility protocol and RVA methods was achieved, indicting that the developed method could be used as an effective alternative for measurement of beta-glucan viscosity.