ABSTRACT
This study used 1H nuclear magnetic resonance (NMR) spin-spin relaxation time (T2) and differential scanning calorimetric (DSC) measurements of unfreezable water content (UFW), to assess water behavior in freshly prepared (25°C), refrigerator-stored (4°C, one day), or freezer-stored (–35°C, one day) doughs containing 5, 10, or 30% whole grain, air-classified β-glucan-diminished, and air-classified β-glucan-enriched (BGB-E) barley flours. Three populations of water were detected by NMR, depending on moisture content of dough, namely, tightly (T21, 2–5 msec), less tightly (T22, 20–50 msec), and weakly (T23, 100–200 msec) bound water. T22 peak was always detectable, and T22 peak time linearly correlated to moisture content of dough in a range of 0.7–2.0 g/g db (r = 0.99, P < 0.05). Freezer storage showed less effect on water mobility in dough compared with refrigerator storage, whereas cooking and cool storage of cooked dough significantly decreased the water mobility (P < 0.05). Adding barley flour steadily decreased the water mobility in dough, and the reduction was more significant with adding BGB-E (P < 0.05). Immobile water content was calculated by extrapolating T22 peak time versus total moisture content in dough and significantly correlated to the UFW content measured by DSC (r = 0.72, P < 0.05).
