Microwave Resonance Technology (MWR) for Process Control in Food Industry Jochen Scholz, Manfred Rahe

22 March 2010Page 2

22 March 2010Page 3 Why is the moisture content so important? Moisture content has deep impact on :  microbiological stability  shelf life  physical and chemical properties  quality  price in some cases: regulations and limits has to be maintained

22 March 2010Page 4 Knowing what really goes on  Process knowledge and control Optimized tolerances  smaller variation bandwidth  moisture content closer to limit Quick and direct quality control  Warning at intervention limits  automated intervention / control  Reducing downtimes  Avoiding faulty batches Measuring on-line saves time and money Why in-process measurement?

22 March 2010Page 5 Moisture measurement technique Measuring frequency: 2 – 3 GHz comparable to mobile phone frequencies but less power! Influence of water dipoles on permittivity  Water selective measurement δ+δ+ δ+δ+ δ-δ- What is Microwave Resonance Technology

22 March 2010Page 6 Main Units of Microwave Resonance Systems

22 March 2010Page 7 Working Principle Sample #1 Amplitude attenuation (B) Sample #2  1 1 22 Sample #1 Frequency shift (A ) Density Independent Attenuation (B) and shift (A) of resonance Microwave moisture value α as function of complex permeability: Measuring Principle: Shift in Frequency and Bandwidth

22 March 2010Page 8  water selective  applicable for powders, granules, pellets, plates, sheets, fibers etc.  2-parameter method: independent on density or product mass in the measurement field  Measures core and surface moisture (penetration depth 2-5cm)  only few influencing matrix factors  low calibration effort longtime stability of calib.  short measurement time  online-/inline applicability  in special cases density or mass measurement possible (simultaneously to moisture determination) Special Characteristics Microwave Resonance Technology

Installation example Installation in tubing after roaster, coffee production 22 March 2010Page 9 Installation planar sensor in tubing moisture content1-5% temperature40 – 80 °C reference method oven drying, 104 °C, 24 h

Installation example Installation in slide shoe on breadcrumbs before dryer 22 March 2010Page 10 PRODUCT SENSOR former 1 measurement/h now 1 measurement/minute (averaging) aim: measurement before and after dryer  dryer controll

Installation example Installation in slide shoe on breadcrumbs before dryer 22 March 2010Page 11

22 March 2010Page 12 maize starch moisture content 5-6 % accuracy to reference method0,2 % repeatability / precision 0,15 % dust ex-protection zone aim: automated dryer control 100% documentation Application example, comparison with reference Installation in drop shaft, gummy bear production

Application example, comparison with reference wheat drying process, before dryer 22 March 2010Page 13 moisture content % reference methodoven drying SD to reference0,2 %

Application example, comparison with reference Pet food moisture and density calibration and validation at Nestlé NRC 22 March 2010Page 14 Calibration and validation experiments at laboratory of Gilles Vuataz, Water Management Network Leader Nestlé Research Center, Lausanne Standard deviation0,2 %Standard deviation0,9 [g/100ml]

22 March 2010Page 15 Summery and conclusions  Moisture content is central quality attribute of many products  Online measurement: important for process control and optimization  Microwave Resonance technology (MWR): appropriate method for process measurement  MWR: offers broad variety for flexible sensor integration  specific advantages compared to other online methods  additional to moisture measurement: possibility for density or mass measurement Microwave Resonance technology (MWR) for process control in food industry: A moisture detection method with exciting prospects

22 March 2010Page 16 Thank you for your attention