Effects of hydrocolloids on dough rheology and bread quality parameters in gluten-free formulations

Rheology and the breadmaking process

Bread properties and crumb structure

Publisher Summary This chapter focuses on “food polymer science” approach and illustrates various recent examples of the way it has been used to define structure–function relationships in food products and processes and to assess and understand the effects of glass transitions and water plasticization on food quality, safety, and stability. The chapter reviews some theoretical principles from the field of synthetic polymer science that have been shown to be applicable to the studies of the glassy state phenomenon in foods and illustrates those applications by means of a broad overview focusing primarily on the most recent experimental studies by a number of groups that have been especially active in this rapidly growing field of research. The results of such studies have demonstrated the major opportunity offered by the food polymer science approach to expand not only the quantitative knowledge but also, of broader practical value in the context of industrial applications, the qualitative understanding of food products and processes with respect to (1) structure–functional property and water relationships and (2) the influences of nonequilibrium glassy and rubbery states on time-dependent mechanical and rheological properties related to quality and storage stability.

Glass transitions and water-food structure interactions

Assessment of hydrocolloid effects on the thermo-mechanical properties of wheat using the Mixolab

Mechanisms that can be responsible for the ability of wheat flour doughs to retain gas are discussed. It is concluded that the relevant types of physical instabilities are Ostwald ripening (disproportionation) and coalescence of gas cells. The extent of Ostwald ripening is probably primarily controlled by surface rheological properties; it certainly affects crumb structure, but it cannot explain the differences in gas retention among doughs from various cereals or various wheat cultivars. It is argued that surface forces only provide a stabilizing mechanism for dough films between gas cells, i.e., against coalescence, for films that are much thinner than the diameter of a starch granule. It is concluded that variation in the potential for gas retention among wheat flour doughs is largely due to variation in bulk rheological properties. We propose a new rheological criterion for the extensibility of dough films between gas cells (and thereby for gas retention) that is based on the strain hardening of the dough in biaxial extension exceeding a specific lower limit. The criterion is translated into measurable parameters. Preliminary experiments on doughs with poor and with satisfactory baking performance illustrate its potential importance.

Am Janssen

Papers

Strain-hardening of dough as a requirement for gas retention