For China's largest brewer, controlling dissolved oxygen levels in beer is vital for ensuring product quality and production volume. Optical measurement technology has not only delivered excellent results, it has also reduced maintenance.
China's largest brewer
Founded in 1903 by German settlers, the Tsingtao Brewery is the largest and most prestigious of the approximately 600 breweries currently operating in China. One of Tsingtao's key production units out of its 48 facilities is located in Qingdao, in the province of Shandong. In operation since 1991, the recent introduction of modern production equipment from Germany and France means the unit is now highly automated, operates with advanced control methods, and has the capacity to produce up to 450 million liters of beer annually.
To a great extent, the quality of beer is associated with the quantity of dissolved oxygen (DO) it contains. Oxygen reacts with proteins and polyphenols in the beer which leads to non-biological instability resulting in reduced shelf life and adversely affected flavor. Consequently, control of DO levels during beer production is always a quality target that Tsingtao focuses on. During production, a significant proportion of dissolved oxygen comes from the filtering process. Therefore, before product enters bright beer tanks, in-line detection of DO prevents out-of-spec beer reaching the filling line.
Since 2003, the brewery has employed METTLER TOLEDO in-line DO measuring equipment at fermentation tanks and filters as well as on other brewery processes. As production at the brewery has increased, clean-in-place (CIP) cycles have become a significant daily operation. To prevent damage to DO sensor membranes from chemicals and high temperatures, the probes have to be withdrawn from the process pipes during CIP and subsequently reinserted. All of which is time consuming for operators. Could METTLER TOLEDO provide a solution?
We suggested a switch from an amperometric measuring system to one based on optical technology. Our InPro 6970i optical DO sensor exploits the phenomenon of fluorescence quenching to determine trace oxygen levels. No membrane is involved and the sensor is largely unaffected by CIP processes.
But resistance to CIP is not the only benefit of the InPro 6970i. Amperometric sensors are liable to incorrectly report high DO levels if flow velocity is too low. The InPro 6970i has a negligible flow velocity requirement, so false DO level alarms are eliminated. Fluorescence quenching technology determines oxygen in liquids very quickly, therefore the response time of the sensor is extremely fast. Additionally, the InPro 6970i detects DO levels down to 2 ppb. Combined, this means the sensor is an excellent tool for reducing out-of-spec production.
Tsingtao Brewery also appreciates the reduced maintenance benefits the InPro 6970i brings. Firstly, sensor drift is very low so calibration is required less frequently than for amperometric probes. Secondly, whereas maintenance on amperometric sensors involves changing membrane and electrolyte, with the InPro 6970i the only part that requires periodic replacement is the OptoCap sensing element. OptoCap exchange is simple and can be completed in under a minute.
The "i" in InPro 6970i denotes that the probe features METTLER TOLEDO's Intelligent Sensor Management (ISM) technology. ISM 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. The remaining lifetime of the sensor and when calibration will next be required, as shown by the Dynamic Lifetime Indicator and Adaptive Calibration Timer, mean that maintenance planning is easy and the risk of sensor failure during production is greatly reduced.
According to Du Shuhai, engineer at the brewery, "On the basis of production exceeding 430 million liters in 2009, the successful application of the InPro 6970i meant that the dissolved oxygen index of all filtered beer was maintained below 50 ppb, and both beer quality and output were improved."
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About Mettler Toledo:
METTLER TOLEDO specializes in the area of precision instruments for professional use. METTLER TOLEDO laboratory instruments are used in research, scientific, drug discovery, and quality control labs, amongst many others in the pharmaceutical, chemical, food and cosmetics industries. METTLER TOLEDO comprehensive industrial solutions cover the various steps in a host of manufacturing processes at many of the same customers that laboratory serves. Solutions range from receiving raw materials through various manufacturing processes, in-line process control and end-of-line packaging control, to logistics and shipping. Increasingly, these solutions are fully integrated into the customer's IT environment, helping automate their workflows. In food retail, our offering for fresh food management ranges from receiving and pre-packaging, to in-store solutions for self-service departments, deli counters, and checkout terminals.