The RVA viscosity profiles of porridge slurry are shown in Fig. 4b. Unlike the viscosity of fresh bread, the viscosity of fresh porridge increased throughout the digestion process. The short preparation and cooking time for porridge does not allow for extensive solubilization of β-glucan so that the initial viscosity is quite low. During digestion, the β-glucan concentration in solution increases as the Mw of the starch and protein decreases, resulting in a net increase in viscosity. The frozen porridge gradually increased in viscosity throughout the digestion process and the viscosities of the final, centrifuged extracts were not significantly different from each other or the fresh porridge (Table 2). The viscosity of the porridge freeze dried after submersion in N2 remained constant throughout the digestion period as macromolecules solubilized and protein and starch were digested. Porridge freeze dried after freezing at -18 or -80 oC had the lowest initial viscosities, indicating low solubility due to dehydration of the macromolecules. The slurry viscosities for these products increased for the first 45-60 min but then gradually decreased again. The viscosities of their final extracts were lower than the fresh or frozen porridges (Table 2) and also lower than their slurry viscosity (Fig. 4b), indicating that other constituents, such as undigested starch, protein and non-soluble fibers, contributed to the viscosity in addition to β- glucan. This was previously shown with the addition of lichenase (endo-(1 → 3)(1 → 4)-β-D-glucan 4-glucanohydrolase) to hydro- lyze β-glucan and eliminate its contribution to the viscosity (Gamel et al., 2012).