CAN PHYSICAL DOUGH TESTS BE USED TO PREDICT BAKING PERFORMANCE?

摘要

Different mixing techniques are applied to potential new wheat lines in breeding programs to identify dough strength and to indicate baking performance. In Australia, instruments such as the Farinograph, the DoughLab and the Extensograph are used routinely to evaluate mixing properties, dough strength and extensibility. In the US the Mixograph is the instrument of choice to evaluate these same characteristics. Both instruments are torque measuring devices, and have different mixing actions; the Farinograph is a pack-squeeze type of gentle kneading action by the two Z-arm or sigma type blades that rotate at different speeds, the Mixograph is more vigorous has 4 vertical pins revolving around 3 stationary pins; this action is the same as the NationalPin mixer for baking. The utilization of wheat flour in the production of a wide variety of products involves the formation of a mixture with water/ingredients leading to dough. Given the complexity of dough, numerous variations in its properties are possible as a result of altering the qualitative and quantitative levels of expression of certain groups of proteins either genetically or environmentally; proteins and their link to quality traits has been established (Cornish, 2001). In quality assessmentthere is also the overriding factor of sources of variation, and whether the variation is attributed to the field or the laboratory (Allen et al, 2000). Extensograph data has also being used to monitor the production of wheat into flour for the baking industry (Oliver and Allen, 1992), even though empirical rheometry methods such as the Extensograph have been recognised as measuring only a narrow section of the bread making process (Weipet, 1989).