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Case Studies

High-Tech Robotic Solutions in Milk Testing

Stäubli Robotics

Milk is among the most strictly regulated foods in the market. As one of the agencies responsible for implementing the Milk Quality Ordinance in Germany, the Milchprüfring Bayern (MPR; Bavarian Association for Raw Milk Testing) testing organization operates conceivably the world’s largest and most modern laboratory (in Wolnzach, Germany). The MPR relies on highly sophisticated automation to ensure reliable analysis of approximately 14 million milk samples annually, delivering a yearly total of 90 million analytical results.
 
The Milchprüfring Bayern e. V. (MPR; Bavarian Association for Raw Milk Testing), tests the quality of milk from approximately 40,000 dairy producers. The agency’s high-tech laboratories in Wolnzach (Germany) process milk samples from close to one million cows each year. Continuously monitored test criteria include fat and protein content, bacteriological quality, freezing point, somatic cell count and the absence of inhibitors.
“MPR relies on advanced laboratory technology in order to be able to work as fast, safe, reliably and cost-effectively as possible. That’s why we decided to make the investment in two innovative systems to analyze inhibitors. The robotic systems from Hamilton Robotics set the standards in this field and allow us to analyze roughly 10,000 samples in under six hours,” states Christine Habel, head of MPR’s Inhibitors division.
In inhibitor screening, milk samples are tested for pharmaceutical residues such as penicillin and sulfonamide. The new Hamilton systems dispense the milk samples into vials within microtiter plates (MTP), incubate the MTPs and perform the optical inhibitor analyses. The completely enclosed systems essentially consist of a Hamilton Microlab STARplus pipetting robot, a microtiter plate reservoir, an incubation chamber, an optical detector and a Stäubli 6-axis TX60 robot which transports the microtiter plates from station to station.
 
Intelligent system-integrated logistics
 
The vials containing the milk samples enter the system in so-called round cassettes, each holding a maximum of 72 sample vials. As the first step, the vials are automatically individualized. A scanner then reads each vial’s barcode information, after which the vials are fed to a pipetting station.
 
While this preparing of the sample vials for the subsequent pipetting is in full swing, a precision Stäubli robot is performing another crucial task on the other side of the system. The Stäubli 6-axis TX60 robot takes the microtiter plates out of a magazine and transports them to a scanner station to read the MTP barcode. Scanning the sample vial barcodes and microplates ensures that each and every sample is meticulously tracked at all times and the final analytical findings will be accurately matched to the respective milk producer.
 
After scanning, the TX60 precisely seats the plates on a transfer unit which conveys two MTPs at a time into exact position on the pipetting robot deck. Hamilton’s Microlab STARplus pipetting robot is one of the highest-performance machines on the market today. With 16 independent and spreadable pipetting channels, the machine transports the smallest amounts of milk from the sample vials into the MTP wells. After each filling operation, the pipetting robot’s needles are automatically fed to a wash station and replaced by a fresh set.
 
The Stäubli TX60 then retrieves the filled MTPs at a defined position and transports them to the incubation chamber’s transfer station where the samples are incubated for approximately 2.5 hours. Christine Habel adds, “The robot’s precision and motion control are particularly important criteria to us when screening for inhibitors. We can only guarantee error-free pipetting when the microtiter plates are exactly positioned. The robot also needs to transport the MTPs at a rapid rate but yet gently and smoothly. The Stäubli TX60 sets the standards for such criteria.”
 
Guaranteed error-free inhibitor analysis
 
Detecting potential inhibitors is as simple an operation as it is efficient. Each of the 96 wells of an MTP contains a defined medium comprising a specific bacterium and Brilliant Black dye. After incubation, any inhibitor in a given milk sample within the well can be identified visually. The medium’s bacterium cannot convert the dye in inhibitor-laden milk such that the sample’s well remains blue. When there are no inhibitors in a milk sample, the dye is readily converted and the well turns an intense yellow.
 
Approximately 2.5 hours later, the robot retrieves the incubated samples from the incubation chamber. After a brief stop to extract condensed liquid, the TX60 heads for an image processing station. The vision system images all the wells in the MTP and sends the data directly to the system computer. Dr. Thomas Zacher, Hamilton application specialist, comments, “Optical detection is a valuable new feature of this system. Automatic analysis of color saturation levels provides reliable results and has several advantages, a main one being that image processing documents all the sample results, another being the system signaling positive samples to the operator right on the monitor.” However, the ultimate assessment of samples is always entrusted to the staff’s expertise and not the system itself.
 
Full automation becomes the only logical solution
 
The reasons for adopting a fully automated approach to inhibitor analysis included a steadily rising volume of samples as well as the desire for a solution which would be as fast as it would be economical. “Manually pipetting far in excess of 10,000 samples on a daily basis is virtually impossible. Not to mention the risk of flawed results given such monotonous activity. That’s why the MPR had already adopted a semi-automated solution quite some time ago. Now that the Hamilton solution gives us full automation, we are far better equipped to meet the requirements of our continually rising workload. The system works fast, reliably and economically,” affirms Christine Habel.
 
That a Stäubli robot is at the heart of the solution is anything but coincidence. For a manufacturer like Hamilton which sets benchmarks in the ultra-precise dosing of liquids for the medical, biotechnological, food and pharmaceutical sectors, only the most state-of-the-art robot supplier is a viable option. “Our systems are engineered in Switzerland to be of particularly high quality. We use our own pipetting robots and our staff has extensive robotic expertise. That’s the very reason why Hamilton chose Stäubli as its 6-axis robot supplier. Not only are their machines technically superior but Stäubli also scores high when it comes to customer service and that explains why we’ve been consistently and successfully integrating Stäubli robots for a number of years,” says Dr. Zacher.
 
The MPR is also very satisfied with its two new Hamilton systems, which have now been up and running for a few months. One striking aspect is how skillfully the almost exclusively female team operate the systems and the robots, underscoring the expertise of the MPR staff as much as the user-friendliness of Hamilton’s systems. Both factors together contribute to the reliability of the systems, running seven days a week, soundly meeting MPR’s high expectations.
 
About Stäubli: Textile Machinery, Connectors and Robotics
Stäubli is a mechatronics solution provider with three dedicated divisions: textile machinery, connectors and robotics. With a workforce of 4000, Stäubli has a presence in 25 countries and agents in 50 countries around the world.
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