Non-invasive monitoring of dough mixing by near infrared spectroscopy

A novel, non-invasive method of monitoring dough development using a diode array near infrared spectrometer has been developed. The variation in two specific absorbance wavelengths in the second derivative spectrum (1160 nm and 1200 nm) as the dough is mixed is shown to follow the same trend as mixer power consumption. Both absorbance features show a reduction in peal; area as dough mixing progresses, reaching a minimum at optimum dough development, and an increase as the dough mixing continues past peak mixer power consumption. Consistent results were obtained for un-yeasted and Full formula doughs made from flours of different strengths using three different laboratory mixers of different mixing action (spiral, z-arm and pin). In the case of the z-arm and pin mixers, the NIR mixing curves predicted longer mixing times than the power consumption curves, and both methods differentiated between flours of different strength. The spiral mixer showed no statistical difference between the mixing times measured by each method, and further, there was no statistical difference between the mixing times for each flour when measured using either method. These differences may be due to mixer design or mixing intensity. The data presented shows the potential of the technique for providing information on the chemical processes that occur during dough development in relation to flour strength and mixing action and intensity. (C) 1998 Academic Press Limited.