Browsing by Subject "calcium"

Oat β-glucan is a non-starch polysaccharide, and it is well-known that oat β-glucan provides physiological functionalities, such as reducing glycemic response. It is proposed that the reduction of glycemic response is due to the elevation of digesta’s viscosity in the intestinal tract, which is attributed to the viscosity generated by β-glucan. An increase in viscosity of digesta is assumed to hinder starch digestion, thus reducing glucose absorption. However, it is not known whether viscous β-glucan or β-glucan gel causes such physiological responses. Thus, the aim of this Master’s thesis was to study the effects of viscous β-glucan on in vitro starch digestion. The in vitro starch digestibility method was adjusted to suit the viscous β-glucan. The hypothesis was that sample containing oat β-glucan would hinder starch hydrolysis compared to the sample without oat β-glucan. Viscosity and viscoelasticity of wheat starch were analyzed to ensure that the concentration of the wheat starch used was appropriate for the study. The viscosities of oat β-glucan solutions at different concentrations were also measured. The in vitro starch digestibility result was evaluated by measuring the concentration of starch hydrolysis product. Viscosity and viscoelasticity tests of wheat starch showed that 4% wheat starch was suitable in the starch digestibility study. The viscosities of various concentrations of oat β-glucan exhibited pseudoplastic flow behavior. In vitro starch digestibility showed that oat β-glucan slowed down the starch hydrolysis. Calcium contained in oat β-glucan was found to enhance the activity of α-amylase, resulting in a higher concentration of the starch hydrolysis product. 2160 µg/g Ca2+ was added to all samples in order to compensate for different Ca2+ concentrations in each sample. The maximum Ca2+ concentration that 1 U α-amylase could utilize was 98 µg/g Ca2+. The results of this study confirmed that the viscous oat β-glucan hindered the starch digestibility compared to the sample without oat β-glucan and calcium ions played a role in starch digestibility.