(2009). The samples were suspended in distilled water (30 mg/mL), heated to 80 °C and stirred for 3 h. After 48 h at 4 °C, the resulting suspensions were loaded on a rheometer with controlled tension, in linear mode, with a shear rate from 0.1 to 100 s−1 at Selleck LY294002 25 °C. The analysis were tested in triplicate and the results were subjected to analysis of variance, followed by Tukey’s test, with p < 0.05 set as the level of significance. The β-glucan concentrate from oat bran contained 32.2% of dry β-glucan, 8.55% of residual protein, 1.5% of residual ash and 57.45% of residual carbohydrates. The carbonyl and carboxyl

contents and the sum (carbonyl + carboxyl) of samples after oxidative treatment are presented in Table 1. The highest carbonyl values were found in the treatments with higher hydrogen peroxide concentrations and reaction Fulvestrant mouse times: 0.9% of H2O2/30 min, 0.6 and 0.9% of H2O2/60 min. The β-glucans oxidised with hydrogen peroxide for 60 min presented higher carboxyl contents than native β-glucan and β-glucans oxidised for 30 min. The treatments with 0.9% of H2O2/30 min and 0.6 and 0.9% of H2O2/60 min presented the highest sums of carbonyl and carboxyl contents (Table 1). Wang and Wang (2003) reported that the carbonyl and carboxyl groups in corn starch increased with the increased intensity of the oxidative treatment.

These results indicated that hydrogen peroxide promoted alterations in the structure of β-glucan similar to those that occur in other polymers, such as chitosan and starch, which can break the glycosidic linkages (Qin, Du, & Xiao, 2002). The swelling power, glucose availability after chemical digestion and fat- and bile acid-binding capacities of native β-glucan and

β-glucan oxidised with hydrogen peroxide are presented in Table 2. The native β-glucan had 14.5 g/g of swelling power, similar to reports by Bae et al. (2009), who found a swelling power of 15.12 g/g for native β-glucan concentrate containing 43% β-glucan. The swelling power of β-glucan increased in treatments with 0.3% and 0.6% of H2O2/30 min, with the highest value (18.94 g/g) for the treatment with 0.3% of H2O2/30 min. However, in the treatment check with 0.9% of H2O2/30 min and in all treatments with 60 min of reaction, the swelling power was decreased (Table 2), indicating more breakages of glycosidic links and thus lower water retention capacity. In starches, low-intensity oxidative treatment can increase swelling power because the depolymerisation of molecules is not very intense (Kuakpetoon & Wang, 2008). However, more intense treatment can cause structural disintegration and reduce swelling power (Sandhu, Kaur, Singh, & Lim, 2008). Bae et al. (2009) also verified a reduction of swelling power in β-glucan from oats when the molecule was partially hydrolysed with the enzyme cellulase, resulting in different molecular weight.