Small strain viscoelastic behaviour of wheat gluten-pentosan mixtures.

摘要

Gluten and water-soluble pentosans were extracted from defatted flours of two different wheat cultivars, having different grain hardness and baking quality. The rheological behaviour of the hydrated gluten samples and the effect of arabinoxylan-rich fractions of water-soluble pentosans (WSP) on their viscoelastic properties were studied in shear by dynamic measurements. The hydrated gluten samples showed the typical viscoelastic behaviour of a transient network, approaching the plateau zone at low frequencies. The WSP had only a small impact on this behaviour, causing a reinforcement of the network, as shown by the increase of storage modulus (G'), but also an increase in dissipative processes caused by a higher degree of structural rearrangements within the network, as shown by the higher frequency dependence of G' and the higher value of the loss angle tangent. By interchanging the gluten and the WSP fractions of the two wheat varieties, it was shown that the observed effect was also dependent on the source from which the WSP originated. The glutens in the presence of WSP were also less sensitive to the thermal treatment than the glutens alone, as shown by the lower magnitude of variation of G' with temperature..