102
acid hydrolysis, acetolysis, and NMR and ESI-MS spectroscopy. The results
indicated that GLSA50-1B was elucidated to be a completely unique β-D-glucan
featured by a 1,6-linked β-D-glucopyranosyl backbone with different length of
branches consisting of terminal and 1,4-linked glucopyranosyl residues, connected
to O-4 of alternative glucose residues in the backbone.
Solution Behaviour
Solubility in water is one of the most important characteristic of β-glucan. In water,
solubility of β-glucans is dependent, above all, on their structure, and this is associated with their origin as well (Rop et al. 2009). It is well documented that the solubility of β-glucan increases with temperature. In general, water solubility chain
conformation, and addition of suitable ionic groups with appropriate degree of substitution can change the bioactivities of polysaccharides (Tao et al. 2006). Soluble
β-glucans are considered to be stronger immunostimulators than insoluble
β-glucans. Zhang et al. (2001) have reported that water-insoluble polysaccharides
exhibit very little bioactivity, whereas their soluble derivatives show high antitumor
and/or antiviral activities. Similarly, Xiao et al. (2004) reported that soluble high
molecular weight yeast β-glucan may improve IFNγ-producing cells in a dosedependent manner, whereas the insoluble β-glucan had no impact.
The viscosity is another important characteristic feature of β-glucan. The viscosity of β-glucan is dependent on the molecular weight, molecular structure, and food
matrix (Kerckhoffs et al. 2003; Bae et al. 2009). The range of relative MW of
β-glucans is quite broad and fluctuates (depending on origin) from tens to thousands
of kilodaltons (kDa) (Rop et al. 2009). High molecular weight β-glucans are most
effective as they are able to form viscous solutions. These are mainly found in
native forms of oat or barley (≥1000 kDa) (Wilson et al. 2004), while food processing or extraction results in reducing β-glucan molecular weight (Rieder et al. 2015;
Tosh et al. 2010).
Oat and mushroom β-glucans within the diet have been reported to reduce human
plasma lipid due to its capability to extend food viscosity (Bae et al. 2009; Andersson
et al. 2010). Studies reported that β-glucans from each oat and mushroom shiitake
exhibited sheer thinning behaviour where the viscosity decreased with higher speed.
They additionally determined that the mushroom diet was better than the oat diet as
a part of a high fat diet as a result of it reduced body weight gain, total fat mass,
plasma triacylglycerol and increased fat faecal excretion (Handayani et al. 2012).
Moreover, viscosity is controlled by β-glucan concentration in solution and β-glucan
MW, and thus the glycaemic response was considerably related to values of concentration MW (Wood et al. 2000). In a study, the relationship of viscosity and MW of
cereal β-glucan in postproandial blood glucose and insulin response and serum cholesterol has been reported (Wood 2007). Furthermore, it has been reported that
endogenous enzymes are to blame for the changes in viscosity. There are a minimum of two endogenous glucan hydrolase enzymes that cause degradation of
N. Jan et al.
acid hydrolysis, acetolysis, and NMR and ESI-MS spectroscopy. The results
indicated that GLSA50-1B was elucidated to be a completely unique β-D-glucan
featured by a 1,6-linked β-D-glucopyranosyl backbone with different length of
branches consisting of terminal and 1,4-linked glucopyranosyl residues, connected
to O-4 of alternative glucose residues in the backbone.
Solution Behaviour
Solubility in water is one of the most important characteristic of β-glucan. In water,
solubility of β-glucans is dependent, above all, on their structure, and this is associated with their origin as well (Rop et al. 2009). It is well documented that the solubility of β-glucan increases with temperature. In general, water solubility chain
conformation, and addition of suitable ionic groups with appropriate degree of substitution can change the bioactivities of polysaccharides (Tao et al. 2006). Soluble
β-glucans are considered to be stronger immunostimulators than insoluble
β-glucans. Zhang et al. (2001) have reported that water-insoluble polysaccharides
exhibit very little bioactivity, whereas their soluble derivatives show high antitumor
and/or antiviral activities. Similarly, Xiao et al. (2004) reported that soluble high
molecular weight yeast β-glucan may improve IFNγ-producing cells in a dosedependent manner, whereas the insoluble β-glucan had no impact.
The viscosity is another important characteristic feature of β-glucan. The viscosity of β-glucan is dependent on the molecular weight, molecular structure, and food
matrix (Kerckhoffs et al. 2003; Bae et al. 2009). The range of relative MW of
β-glucans is quite broad and fluctuates (depending on origin) from tens to thousands
of kilodaltons (kDa) (Rop et al. 2009). High molecular weight β-glucans are most
effective as they are able to form viscous solutions. These are mainly found in
native forms of oat or barley (≥1000 kDa) (Wilson et al. 2004), while food processing or extraction results in reducing β-glucan molecular weight (Rieder et al. 2015;
Tosh et al. 2010).
Oat and mushroom β-glucans within the diet have been reported to reduce human
plasma lipid due to its capability to extend food viscosity (Bae et al. 2009; Andersson
et al. 2010). Studies reported that β-glucans from each oat and mushroom shiitake
exhibited sheer thinning behaviour where the viscosity decreased with higher speed.
They additionally determined that the mushroom diet was better than the oat diet as
a part of a high fat diet as a result of it reduced body weight gain, total fat mass,
plasma triacylglycerol and increased fat faecal excretion (Handayani et al. 2012).
Moreover, viscosity is controlled by β-glucan concentration in solution and β-glucan
MW, and thus the glycaemic response was considerably related to values of concentration MW (Wood et al. 2000). In a study, the relationship of viscosity and MW of
cereal β-glucan in postproandial blood glucose and insulin response and serum cholesterol has been reported (Wood 2007). Furthermore, it has been reported that
endogenous enzymes are to blame for the changes in viscosity. There are a minimum of two endogenous glucan hydrolase enzymes that cause degradation of
N. Jan et al.