Electrical and optical methods for the determination of important process parameters during food production and quality control

Optical measurements are of primary importance for the control of food production. Satellite based hyper-spectral imaging for example is enabling a continuous monitoring of the plant growth worldwide. Another important field of application are non-invasive techniques for the control of the further food processing. In the present talk an overview will be given on the different measurement techniques that are related to the production of beverages. In particular the monitoring of the process of beer fermentation and the control of the composition of milk will be shown in more detail. In the latter case besides more conventional techniques using for example a turbidity sensor, some first measurement results, regarding the innovative concept of fluctuation-enhanced sensing are presented, where the low-frequency noise spectral behavior rather than the amplitude of the optical signal is shown to be very sensitive to compositional changes of a milk-water mixture. The main advantage of this technique is the easier calibration. It will also be shown, that the combination of optical techniques with other measurement techniques can strongly increase the probability of successful detection of small changes during food processing. For example, the combination of voltametric and spectro-photometric techniques has been shown to enable a clear discrimination between different brands of commercial beers.