Examples of the application of optical process and quality sensing (OPQS) to beer brewing and polyurethane foaming processes


Optical methods play an important role in process analytical technologies (PAT). Four examples of optical process and quality sensing (OPQS) are presented, which are based on three important experimental techniques: near-infrared absorption, luminescence quenching, and a novel method, photon density wave (PDW) spectroscopy. These are used to evaluate four process and quality parameters related to beer brewing and polyurethane (PU) foaming processes: the ethanol content and the oxygen (O2) content in beer, the biomass in a bioreactor, and the cellular structures of PU foam produced in a pilot production plant.

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  1. 1.

    See, for example (a) Anton Paar—Lab density & concentration meter/Alcohol Meters; online at: http://www.anton-paar.com/density-meter/lab-density_cxsn-5nuflp.en.0. jsp; (b) Alcohol Analyser; online at: http://www.nirtech.zip.com.au/AlcoholAnalyser.htm; (c) McNab Food & Beverage Industry Systems, online at: http://www.themcnab.com/food_beverage.htm; (d) FOSS—Beer; online at: http://www.foss.dk/c/p/solutions/customersegments/Beer/default.asp

  2. 2.

    See, for example (a) PreSens GmbH; online at: http://www.presens.de/html/start.html; (b) Hac-Lange; online at: http://shop.hach-lange.com/shop/action_q/news/news_id/100/lkz/II/spkz/en/; (c) Fiber Optic Oxygen Sensors; online at: http://www.oceanoptics.com/products/foxysystem.asp; (d) Submersible sensors—Oxygen Optodes 3830/3975/3930—Aanderaa Instruments; online at: http://www.aanderaa.no/render.asp?ID=156&segment=46&


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Correspondence to Hans-Gerd Löhmannsröben.

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Engelhard, S., Kumke, M.U. & Löhmannsröben, HG. Examples of the application of optical process and quality sensing (OPQS) to beer brewing and polyurethane foaming processes. Anal Bioanal Chem 384, 1107–1112 (2006). https://doi.org/10.1007/s00216-005-3364-4

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  • Process analytical technology
  • Beer
  • Biomass
  • Foam analysis
  • NIR spectroscopy
  • Fluorescence quenching
  • Photon density wave spectroscopy