Controlling dissolved oxygen levels in beer is vital for ensuring product quality and production volume. Optical measurement technology from Mettler Toledo has delivered excellent results and also reduced maintenance requirements.
Founded in 1903 by German settlers, the Tsingtao Brewery is one of the largest and most prestigious of the approximately 600 breweries currently operating in China. One of Tsingtao's key production units is located in Qingdao in the province of Shandong.
Thanks to modern production equipment from Germany and France, the unit is now highly automated, operates with advanced control methods and has the capacity to produce up to 450 million litres of beer annually.
Dissolved oxygen or DO content impacts the quality of beer to a large extent. Oxygen reacts with proteins and polyphenols in the beer, leading to non-biological instability, resulting in reduced shelf life and adversely affecting flavour.
A significant proportion of DO comes from the filtering process during production. In-line detection of dissolved oxygen prior to the product entering the beer tanks prevents out-of-spec beer reaching the filling line.
Mettler Toledo’s in-line DO measuring equipment has been employed at the Qingdao facility since 2003, at fermentation tanks and filters as well as on various brewery processes. But the increasing production has also increased clean-in-place (CIP) cycles, creating concerns for potential damage to the DO sensor membranes from chemicals and high temperatures.
To prevent the downtime caused by the CIP cycles, Mettler Toledo suggested a switch from an amperometric measuring system to one based on optical technology. The company’s InPro 6970i optical dissolved oxygen sensors exploit the phenomenon of fluorescence quenching to determine trace oxygen levels without involving membranes while remaining largely unaffected by CIP processes.
Key benefits of Mettler Toledo’s InPro 6970i optical DO sensors:
- Resistance to CIP processes
- Negligible flow velocity requirement eliminates false DO level alarms
- Fluorescence quenching technology determines oxygen in liquids very quickly, resulting in faster response time of the sensor
- Detects DO levels down to 2 ppb
- Low sensor drift results in less frequent calibration requirement
- OptoCap sensing element only part that requires periodic replacement through a simple 1-minute exchange
- Mettler Toledo’s Intelligent Sensor Management (ISM) technology brings additional maintenance benefits that help sustain Tsingtao's round-the-clock production
- Advanced sensor diagnostic tools displayed on the connected transmitter provide real-time data on the probe's condition
- Dynamic Lifetime Indicator and Adaptive Calibration Timer allow easy maintenance planning and reduce risk of sensor failure