It was reported earlier that the frozen storage of bread containing barley β-glucan at -20 oC for 7 days had less effect on β- glucan viscosity and solubility than the storage at room temperature (23 oC) or refrigeration (4 oC) (Moriartey et al., 2011). A commercially manufactured oat crispbread (3.7% β-glucan) previously tested (Regand et al., 2009) had lower β-glucan Mw (1.97 kg/ mol). Although the crispbread was air dried after baking, the β-glucan solubility was much higher (61.3%). The viscosity of the extract measured on 20 g of sample using the shaking water bath method was 12.3 mPa s and in vivo testing did not show significant reduction in glycemic response compared to wheat crispbread.
Neither freezing nor freeze drying using liquid nitrogen had significant impact on the viscosity and solubility of β-glucan in bread using either digestion methods. Thus, liquid nitrogen appears to be the optimum treatment in minimizing the physicochemical changes of β-glucan in oat bran bread.