Effect of aging and ice-structuring proteins on the physical properties of frozen flour-water mixtures

Abstract

The present work investigates the effect of aging and ice-structuring proteins at low levels of solids (0.1% w/w) on the physical properties of frozen flour-water mixtures (37.5% w/w moisture). Differential scanning calorimetry, nuclear magnetic resonance, dynamic oscillation on shear, creep testing and electron microscopy were employed to explore the underlying molecular aspects of dough deterioration. Starch granules are embedded in a continuous rather than a fibrous gluten network and it was found that in such a system ice recrystallization as opposed to cryo-dehydration is the mechanism responsible for alteration of the structural characteristics of the material on storage. Deterioration of the mechanical properties continued unabated for 30 days of aging with the ice-structuring proteins being unable to offer protection against recrystallization at the concentration level studied (0.1% w/w). Furthermore, storage near the melting point of ice of the flour-water sample was found to accelerate the structural losses owing to increasing water mobility at this regime. © 2007 Elsevier Ltd. All rights reserved.