Reologia

Journal of Food Engineering 83 (2007) 475–482 www.elsevier.com/locate/jfoodeng

A comparison of the ability of several small and large deformation rheological measurements of wheat dough to predict baking behaviour
Valentina Stojceska a, Francis Butler a,*, Eimear Gallagher b, Denise Keehan b
a

School of Agriculture, Food Science and Veterinary Medicine, University College Dublin,Earlsfort Terrace, Dublin 2, Ireland b Teagasc, National Food Centre, Dunsinea, Castleknock, Dublin 15, Ireland Received 8 February 2007; accepted 10 February 2007 Available online 24 February 2007

Abstract The rheological characteristics of twenty wheat flour samples obtained from four organic flour blends and a non-organic control were compared in relation to their ability to predict subsequent loafvolume in the baked bread. The flour samples considered had protein contents that varied between 11–14 g/100 g. Four different rheological methods were employed. Oscillatory stress rheometry on the protein gel extracted from the wheat flour, oscillatory stress rheometry and creep measurement on undeveloped dough samples and biaxial extensional measurements on simple flour–water doughs. None of thefundamental rheological parameters correlated with loaf volume. There was a correlation between the storage modulus of the gel protein and storage modulus for the undeveloped dough (r = 0.85). There was a weak negative correlation between protein content and biaxial extensional viscosity (r = À0.62). Stepwise multiple regression related loaf volume to dough stability time (measured on theFarinograph) and tan (phase angle) for the undeveloped dough samples (overall model r2 = 0.54). The results indicate that the four rheological tests considered could not be used as predictors of subsequent loaf volume when the bread is baked. Ó 2007 Elsevier Ltd. All rights reserved.
Keywords: Wheat dough; Oscillatory stress rheometry; Wheat protein gel; Undeveloped dough; Biaxial extension; Loaf volume1. Introduction Rheological properties of bread dough are important to the baker for two reasons. First, they determine the behaviour of dough pieces during mechanical handling and second, they affect the processes governing bubble growth and stability during proofing and baking. Dough is a complex mixture of flour constituents, water, yeast, salt, malt enzymes, flour improvers, sugar, fats,emulsifiers, milk or soy solids and mould inhibitors. Nearly all the ingredients affect the rheology of dough to a certain extent, but most of the rheological properties are derived from flour, water and
*

Corresponding author. Tel.: +353 1 7167473; fax: +353 1 4752119. E-mail address: f.butler@ucd.ie (F. Butler).

air (Spies, 1989). Dough is a principal intermediate stage in the transformation ofwheat, through flour, into bread. Its main constituents are those that are delivered from the flour, most importantly the proteins, both soluble and insoluble, and the carbohydrates. Gluten is the major protein in wheat flour doughs. The gluten proteins have a large average molecular weight (about 3 million) and are primarily responsible for the visco-elastic behaviour of dough (Spies, 1989). Thereis a widespread belief that the rheological properties of dough are related to baking quality (Dobraszczyk, 2003). Empirical rheological tests such as the farinograph and the extensograph have long been used to test flour quality as part of routine quality control work within the baking industry. Empirical tests by their

0260-8774/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.doi:10.1016/j.jfoodeng.2007.02.043

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V. Stojceska et al. / Journal of Food Engineering 83 (2007) 475–482

nature are dependent on the type of equipment used and it is not possible to compare results directly between different types of equipment. Fundamental rheological tests measure well defined properties of the material and the results are independent of the test equipment and can...