1H Nuclear Magnetic Resonance (NMR) and Differential Scanning Calorimetry (DSC) Studies of Water Mobility in Dough Systems Containing Barley Flour

This study used H-1 nuclear magnetic resonance (NMR) spin-spin relaxation time (T-2) and differential scanning calorimetric (DSC) measurements of unfreezable water content (UFW), to assess water behavior in freshly prepared (25 degrees C), refrigerator-stored (4 degrees C, one day), or freezer-stored (-35 degrees C, one day) doughs containing 5, 10, or 30% whole grain, air-classified beta-glucan-diminished, and air-classified beta-glucan-enriched (BGB-E) barley flours. Three populations of water were detected by NMR, depending on moisture content of dough, namely, tightly (T-21, 2-5 msec), less tightly (T-22, 20-50 msec), and weakly (T-23, 100-200 msec) bound water. T-22 peak was always detectable, and T-22 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 T-22 peak time versus total moisture content in dough and significantly correlated to the UFW content measured by DSC (r = 0.72, P < 0.05).