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Control of bread dough mixing operations using NIR spectroscopy. S. J. MILLAR (1), J. M. Alava (1),
and S. E. Salmon (1). (1) Campden & Chorleywood Food Research Association.
Dough mixing is a critical stage in the process of breadmaking and
must be carefully controlled to produce the optimum results. Traditional methods of assessing dough
development rely on mechanical measurement of the physical properties of the dough. Such methods do not
give information that relates directly to the chemical changes occurring and may be unsuitable for on-line
use. NIR spectroscopy has been used for remote assessment of dough during mixing using Chorleywood
Breadmaking Process (CBP) Z-blade mixers for a range of flours of differing breadmaking qualities. The
optimum mixing time, as determined using a Perten DA-7000 diode array NIR spectrometer, was shown to
relate well to the rheological properties of the gel protein fraction of the flours (a measure of flour
breadmaking potential). When bread was baked at a number of different mixing times, variation in the bread
quality was observed which was related to the NIR mixing curve. For five single variety flours covering a
range of gluten properties, the finest crumb texture (as measured by image analysis) occurred early in the
mixing process before the greatest loaf volume was achieved. The optimum mixing time determined using
the NIR traces occurred at an intermediate point leading to the conclusion that on-line optimisation of the
mixing process for particular bread charcteristics is possible. The effect of varying rate of work input on the
NIR mixing curves and on the final bread quality was assessed with a view to extending the use of the
technique to different mixers and mixing conditions.
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