145 Effect of mixing conditions on glutenin macropolymer breakdown and reformation.

C. V. SKINNER and J. D. Schofield. Department of Food Science and Technology, The University of Reading, RG6 6AP, UK, and G. Buldolfsen Novo Nordisk A/S, Novo Alle, 2880 Bagsvaerd, Denmark.

The effects on breadmaking quality of different mixing conditions and of additives such as ascorbic acid, potassium bromate and glucose oxidase have been assessed using the Glutenin Macropolymer (GMP) fraction as a measure. Significant effects on GMP quantity were observed using different mixers and different oxidising additives during both GMP depolymerisation and reformation. For example, GMP depolymerisation, in the presence of ascorbic acid, was less complete for doughs mixed in the Farinograph than for those mixed in pin mixers, such as the Mixograph. Differences in the levels of GMP reformation between mixers were also seen. Gluten samples prepared from differently treated doughs were assessed rheologically using small-scale oscillatory and creep/recovery tests. Unexpectedly, gluten samples from both oxidant and reductant treated doughs showed greater deformability than gluten samples from untreated doughs. Correlations between gluten rheological behaviour and GMP breakdown are being evaluated.