Rachel is a production manager at a medium-sized U.S. dairy company. She enjoys her job, but a reoccurring problem is frustrating her, and the most recent occurrence was very costly for the dairy.
Lab tests of a batch of yogurt showed that the pH was way out of range, and the yogurt couldn’t be used. Half of the batch was already packaged and had to be crushed.
What made it worse was that the batch was for a recently launched yogurt brand. The new brand was a great success, and the loss of the batch would mean empty shelves at some of its customers’ stores.
On top of this, because of the new line’s popularity, Rachel and her team have been tasked with increasing production with the same equipment they’ve been using for years. In addition, management demands that they win the challenge of sustainable production by reducing energy consumption. This was a tricky problem to solve.
She was also having difficulty finding skilled people experienced in tasks like sampling and measuring whom she could rely on to help her make the right production decisions.
After some research, Rachel found something that might not solve all her problems but would solve a lot of them and would definitely stop out-of-spec yogurt batches!
But before we get to that…
Sampling: Only a Snapshot…
Sampling relates to quality control – it has nothing to do with process control and even less with process automation. It doesn't save time or effort, so it doesn't help make F&B plants more productive or more efficient.
pH plays an essential role in food and beverage production as the pH level affects the speed and comprehensiveness of reactions during many production processes. Monitoring pH is, therefore, critical for both product quality and process control.
Typically, a sample is taken every 20 minutes or up to once an hour during production. This provides valuable information about the quality of the product and the process - but only up to the moment the sample is taken. So, the sample is just a snapshot of what has already happened in the process.
Production managers can only try to influence the subsequent process based on the information from that snapshot.
... and Highly Error-prone
What’s more, the results can be subject to significant error: the sample may change between being extracted and being analyzed.
Any delay in running the test, even just a simple phone call taken by the lab employee tasked with the measurement, can result in a false result; or, a sample is assigned to the wrong tank due to lack of attention; or... or... or. The sources of error are many.
Glass and ISFET Sensors: Neither Are Satisfactory
Knowing the pH at any point in the process makes it possible to speed up, slow down, balance, or even stop the process when a desired value is reached. In-line pH sensors can be used to measure the pH throughout the process, from when the milk is delivered to when the final product is packaged.
Until now, however, no in-line pH sensor has been able to fully meet the expectations of the F&B industry:
Traditional in-line pH sensors use a glass membrane. The problem is obvious: the glass can break during handling, cleaning-in-place (CIP), or even from just being in the process, for example, when solid components in the medium, such as ice lumps during ice cream production, damage if not completely shatter the glass.
Ion-sensitive field effect transistor (ISFET) was the next technology on the market. ISFET sensors are not made of glass but instead have a chip with a pH-sensitive surface. At first glance, this makes them more suitable for food production than traditional glass sensors, but the chips are not very robust, and the sensors require frequent calibration. This results in short maintenance intervals and many production interruptions. More than that, ISFET sensors don’t tolerate CIP.
No wonder in-line pH measurement has not gained a foothold in the F&B industry.
Until now.
The InPro X1 - A New Era in pH Measurement
We believe that in-line pH measurement is the future of the F&B industry. It allows our customers to fully control and automate their processes, be more productive, use their equipment more efficiently and sustainably, and track every second of the process. That's why we set out to develop an in-line pH sensor that is as accurate as a glass sensor but super robust, says Balz Aebli, Product Manager at METTLER TOLEDO.
It took several years to develop, but now it’s the world's first robust, CIP-resistant, in-line pH sensor - the InPro X1™ HLS. Its accuracy is at least as good as that of the best in-line and laboratory sensors, and it eliminates the need for pH measurement with grab samples.
It's truly a game changer, says Balz. For decades, the dairy industry’s been asking for a safe, in-line pH sensor that will tolerate CIP. Now they have one.
Unbreakable pH Sensor for the Highest Production Safety
For decades, the food and beverage industry’s been looking for a food safe, in-line pH sensor that withstands cleaning processes. As detailed in this white paper, the InPro X1 provides exactly this.
Understanding the Fermentation Process
The graph illustrates the fermentation process in yogurt production, showing the interplay between pH, temperature, and acidity over time.
The dark blue curve represents the pH value, which decreases as cultures metabolize sugar and produce acids, indicating increased acidity essential for yogurt quality.
The light blue curve tracks the yogurt's temperature, which is crucial for controlling fermentation speed and achieving the desired final product.
Green marks indicate sample-measured acidity values, serving as checkpoints to ensure the fermentation process meets specifications.
As the process progresses, the in-line pH sensor reports all it sees.
Exploit the Advantages of In-line Measurement to the Full
By measuring in line with the new InPro X1, production managers like Rachel no longer have to rely on samples taken only every 20 minutes. At any point in the production process, they now have reliable, real-time information on the current pH value.
Continuous monitoring makes the entire process transparent, and the operator can actively intervene and adjust if progress is too slow or too fast. Even more can be achieved by setting thresholds: a reaction can be automatically triggered in the system when these thresholds are reached, exceeded, or fallen below. Thus, the entire process can be automated.
Higher Effficiency and Product Quality
Holger Schmidt, F&B Industry Manager, explains: The production manager can set parameters and limit values within the control system. For example, in yogurt production, once the tank is full the culture is dosed, and as fermentation progresses, the pH drops. The InPro X1 constantly provides a pH reading and when the pH reaches the desired level, the tank can be cooled, stopping fermentation.
In addition to improved product quality and safety, a perfectly regulated production process is faster and more efficient, as throughput times and temperature are precisely controlled. This ensures optimal equipment utilization while reducing energy consumption and resource usage.
Better Process Safety
Errors in the process, such as contamination by bacteria or cleaning agents, can also be detected immediately.
Thanks to in-line measurement, it’s also possible to determine if potentially sour milk has been delivered, because all the milk is tested, not just individual samples.
The same applies if the milk has been stored in intermediate storage tanks. A critical control point (CCP) before packaging ensures that no cleaning detergents are accidentally included in the finished product.
Traceability
Traceability of incoming milk quality is a huge gain for process quality, says Holger. We see this at a German dairy where the InPro X1 measures all the incoming milk, not just samples from each tank section. If there’s a delay in downloading milk, you can get separation in the tank sections, and therefore, a sample may not be representative. Continuous measurement with the InPro X1 spots everything.
Thanks to in-line production monitoring, every step of the process - from raw material delivery to packaging - is fully traceable. This is particularly important for companies committed to the Global Food Safety Initiative. In the case of the German dairy mentioned, integrating the information and storing it with the batch also allows full traceability from farm to form.
Equipment Protection
InPro X1 users also benefit when it comes to protecting their equipment. Based on a customer case, Holger explains:
During processing of whey, the customer uses the pH measurement from the InPro X1 to determine if the whey’s still sweet. The whey then passes through a filtration system. During cleaning, measurements from the InPro X1 are used to track the caustic concentration. If pH exceeds 11, the membranes in the filtration equipment could be damaged and would need to be replaced.
Similar applications are in place with customers in New Zealand and the U.S., in these cases for lactose, and the first equipment manufacturer has begun implementing the InPro X1 to improve process automation and customer satisfaction.
Hundreds of Correct Measurements Average the Noise
In-line measurement shows exactly what happens during and at every stage of the process, as accurately and precisely as measuring the sample in the laboratory.
It's no wonder that in-line pH measurement is already well established in industries such as chemicals and pharmaceuticals. What often irritates users in the F&B industry, however, is the visible noise in the control system reading.
This is because a medium such as milk is not a homogeneous mass. The InPro X1 detects all variations, even unwanted signal noise caused by gas bubbles. InPro X1 cleans the data, so you get only the precise pH measurement.
The X-Chip - The Heart of the InPro X1
The X-Chip, a completely new technology that outperforms all existing pH sensing technologies, is the actual sensor and the heart of the InPro X1. Located in a titanium tip, the X-Chip is in direct contact with the medium and uses the same potentiometric measuring principle as pH-sensitive glass. However, the lithium silicate surface of the X-Chip is bonded to a metal layer in a composite construction and is highly robust.
A temperature sensor is located close to the X-Chip for temperature compensation, and the sensor’s body is made of very strong, food-grade PEEK polymer.
InPro X1 is one of ourIntelligent Sensor Management (ISM™) sensors. One of the main advantages of ISM is that the analog measurement signal is converted in the sensor to a robust digital signal that suffers no loss from sensor to transmitter.
The InPro X1 is permanently installed in the equipment, reducing installation and operating costs. It is designed to not only tolerate but also support CIP cleaning as it’s not affected by rapid temperature changes, is resistant to all cleaning media and, therefore, can be used to indicate the cleaning activity of the caustic.
The sensor always shows the current pH value in the equipment. And thanks to CIP, it's always at the same hygienic level as the rest of the system and ready for use whenever it's put into operation, explains Balz.
Cross-section of InPro X1
Discover the innovative design of the InPro X1 digital pH sensor through this detailed cross-section video.
pH Sensors Used as Drumsticks? Surely Not!
"We did our best to break it!"
We had a lot of fun trying to break the InPro X1, says Balz. We threw them across the room, dropped them from a roof, drove over them, and even used two sensors as drumsticks!
With over a thousand InPro X1s in use by customers worldwide, no mechanical damage has been recorded. The sensor’s even passed the MIL-STD-810H drop test, a rigorous procedure defined by the U.S. military.
Solid performance
The sensor’s robustness is particularly useful in high-viscosity media. Holger Schmidt gives two examples:
Soured butter takes a while to pass through the first stage of the butter making machine. During this time, the cultures added at the inlet have time to work and lower the pH value. By controlling the result in-line, it's possible to apply culture dosing before the second half of the buttering process, saving time.
Customers in England have already successfully applied this control option. The sensor also works in mozzarella cheese production, where there’s an even higher viscosity. At an Italian customer, the InPro X1 controls the pH and gives an early warning if the product is not within the desired pH range.
Holger Schmidt, Industry Manager for Food & Beverage Industry
Fully Compatible and Easy to Handle
The InPro X1 is fully compatible with existing equipment. It can be easily retrofitted using a simple process fitting such as METTLER TOLEDO’s InFit 761/NC.
Mounted with an Ingold, SMS, DIN11851, clamp, or Varinline connection, the installation is 3A and EHEDG certified, and straightforward to clean.
Thanks to another feature of ISM, predictive diagnostic tools, the days remaining until sensor calibration and replacement should be performed are displayed on the connected transmitter, so maintenance work can be scheduled during non-production times, avoiding unplanned process interruptions.
After 80 Years - Finally, a Reliable In-line Sensor
Rachel, the production manager, is impressed by the possibilities offered by the InPro X1 and its high accuracy and robustness.
X-Chip technology, developed entirely in-house by METTLER TOLEDO, is the first innovation in the pH sensor market for the F&B industry after some 80 years of glass and 40 years of ISFET technology. The sensor marks the beginning of a new era: For the first time, in-line pH measurement in dairy production and other food production that is reliable and safe - in every sense.
Accurate and Faster Production Processes
Rachel wants her dairy to reap the benefits of in-line pH measurement. More accurate and faster production processes would allow her team to produce more within the same period and without impacting quality. Less maintenance would make their production even more efficient, and management would appreciate the improved cost/quality/performance ratio.
She is particularly impressed with the ability to track 100% of the production process and the ease of use of the sensor. For Rachel, lost yogurt batches due to out-of-spec pH are going to be a thing of the past.
Are you interested in using the InPro X1 in your production?
.png/_jcr_content/renditions/cq5dam.web.1280.1280.png "In-Line pH Probe / ORP (Redox) Probe")
.jpg/_jcr_content/renditions/cq5dam.web.1280.1280.jpeg "Sensor Housings and Sensor Cleaning Systems")
.png/_jcr_content/renditions/cq5dam.web.240.240.webp "Transmitters")