Application of the Rapid Visco Analyzer (RVA) as an Effective Rheological Tool for Measurement of β‐Glucan Viscosity

Abstract

The physiochemical characteristics of β‐glucan in oat and barley foods can affect human physiological response. A method for continuous measurement of β‐glucan viscosity with a Rapid Visco Analyzer (RVA) was developed to overcome the complexity of the common protocols based on in vitro digestion methods. The effects of several parameters on viscosity and solubility were considered. Oat cereal foods showed different RVA viscosity profiles depending on their physiochemical characteristics. Products high in starch exhibited a high initial viscosity that was reduced by α‐amylase action, whereas products with low amounts of starch exhibited a slow increase in viscosity. The viscosity of all samples reached a plateau in the viscosity curve after 1–2 hr, which is the key for obtaining reproducible results. Optimum digestion condition was achieved using sodium phosphate buffer (pH 6.9) and 1% β‐glucan dispersion at 37°C and 160 rpm. A particle size of <0.6 mm gave more consistent viscosities than did larger particles without affecting the solubility of β‐glucan. Pancreatin and α‐amylase concentrations 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 β‐glucan viscosity.

Effect of Heat Treatments on Starch Pasting, Particle Size, and Color of Whole‐Grain Barley

“…In this study, starch pasting was measured both with and without lichenase addition to evaluate the contribution of BG to the starch-pasting profile. Work done by Wang et al (2016) and Gamel et al (2012) has shown that addition of 25 µL of lichenase to oat flour slurries in the Rapid Visco Analyzer at 37°C resulted in an immediate reduction in viscosity to baseline, confirming the rheological contribution of BG in the oat slurry. Liu et al (2010) previously determined that BG contributed significantly to starch pasting.…”

Effect of Heat Treatments on Microbial Load and Associated Changes to β‐Glucan Physicochemical Properties in Whole Grain Barley

“…However, other physicochemical properties of BG also influence its nutritional functionality and health benefits. The BG content was maintained at 1% during the in vitro extraction so that it would not interfere with the viscosity and solubility results (Gamel et al 2012). The mean BG in vitro digest extract viscosity, MW, and solubility of the commercial barley end-products are summarized in Table III.…”

Effect of Processing on Viscosity and Molecular Weight of (1,3)(1,4)‐β‐Glucan in Western Australian Oat Cultivars

“…The Gamel et al (2012Gamel et al ( , 2014 method was used to determine the viscosity of b-glucan by using the Rapid Visco Analyzer (RVA) (Newport Scientific Pty. The Gamel et al (2012Gamel et al ( , 2014 method was used to determine the viscosity of b-glucan by using the Rapid Visco Analyzer (RVA) (Newport Scientific Pty.…”

“…To remove particulate matter, the flour slurry was centrifuged at the end of enzymatic digestion in the RVA, and the supernatant viscosity was measured with a viscometer (DV-I + viscometer, Brookfield) as suggested by Gamel et al (2012Gamel et al ( , 2014. To remove particulate matter, the flour slurry was centrifuged at the end of enzymatic digestion in the RVA, and the supernatant viscosity was measured with a viscometer (DV-I + viscometer, Brookfield) as suggested by Gamel et al (2012Gamel et al ( , 2014.…”

“…Oat food consumption has been associated with a number of health benefits because of the presence and amount of viscous soluble fiber (1,3)(1,4)-b-glucan found in the endosperm cell wall (Johansson et al 2000;Daou and Zhang 2012;Gamel et al 2012;Xu 2012). Consumption of oat dietary fiber can effectively lower serum cholesterol, moderate postprandial blood glucose levels and insulin levels, and help control weight through increased satiety (Ripsin et al 1992;Hallfrisch et al 1995;Davy et al 2002;Biörklund et al 2005;Wood 2007;Regand et al 2011;Daou and Zhang 2012;Stewart and McDougall 2014;Wang and Ellis 2014;Whitehead et al 2014).…”