Cereal Chem. 73 (5):618-624  |  VIEW ARTICLE

Proteins

(^2)H and (^17)O Nuclear Magnetic Resonance Study of Water in Gluten in the Glassy and Rubbery State.

George Cherian (1) and Pavinee Chinachoti (1). (1) Department of Food Science, University of Massachusetts, Amherst, MA 01003. Phone: 413/545-2276. Fax: 413/545-1262. Accepted July 4, 1996. Copyright 1996 by the American Association of Cereal Chemists, Inc. 

Water mobility in hydrated gluten at 0-50% mc was studied using (^17)O and (^2)H nuclear magnetic resonance (NMR). Glass transition behavior measured by dynamic mechanical analyzer (DMA) and by differential scanning calorimetry (DSC) was compared to the NMR signal intensity. The (^2)H NMR signal intensity increased during glassy-rubbery transition due to hydration. (^17)O NMR detected the signal when >0.21 g of water/g total occurred in the "free" or bulk water region, as determined from the sorption isotherm. Freezable water was only observed at >18% mc, when the sample was in the rubbery state (beyond the midpoint glass transition) and water was unfreezable in the glassy region. Results from the different techniques (NMR, DMA, DSC, and sorption isotherm) showed good correlation, although experimental conditions, sample preparations, and the time frame of each experiment were inherently different.