Meet the pH challenges in food and beverage applications

Thanks to breakthrough X-Chip™ technology, InPro X1™ pH sensors are unbreakable*, enabling in-line pH measurement in applications with the highest product safety requirements.

Measuring in-line enables better process control, leading to higher product quality and increased yield. InPro X1 sensors are sanitizable using standard industrial processes without the need of expensive and maintenance-heavy retractable equipment. The InPro X1 complies with all relevant standards for the food and beverage industry and can be easily implemented with the same Standard Operating Procedures valid for glass pH electrodes.

Typical pH measurement challenges in the food and beverage industry

pH measurement is used in a plethora of industrial processes for monitoring product quality, increasing process efficiency, ensuring plant safety or monitoring wastewater.

Until recently, glass-bulb pH sensors provided the most reliable measurement performance. However, challenges with glass electrodes correlated with their need for frequent calibration and poor mechanical strength has limited their use in the production of beverages, dairy products and other foods.

Regular maintenance of pH sensors is necessary for maintaining measurement reliability: cleaning to prevent fouling and build-up of material that can interfere with sensor performance, and calibration to correct for measurement drift. It is exposure to high temperatures (cleaning-in-place) and/or harsh conditions that cause the most drift of a pH sensor’s measurement signal, therefore shortening required maintenance intervals. The more often maintenance on sensors is performed, the higher the operating costs. A pH sensor failure due to glass breakage will, in the best case, cause production downtime. At worst it can lead to expensive rework or even discarding of an entire production batch because of contamination of the product with glass splinters. Understandably, in the food and beverage industry, the use of in-line glass electrodes is only permitted in non-critical processes.

Figure 1: pH measurement technology innovation in the InPro X1 tip in comparison with traditional glass pH electrodes

No risk of glass contamination

As a response to industry challenges, METTLER TOLEDO has developed a new technology for measuring pH: the X-Chip.

X-Chip is a fully solid composite pH-sensing element with exceptional mechanical resistance. The X-Chip uses the same potentiometric measurement principle as pH-sensitive glass normally used in pH sensors.

Figure 2: Food-Safe, CIP Resistant, In-Line pH. The InPro X1 HLS is a digital, food-safe, in-line pH sensor that withstands clean-in-place processes. The sensor's unbreakable X-Chip technology eliminates the risk of glass contamination.

The surface of the X-Chip is in contact with the measuring solution. Here, as in traditional electrodes, a gel layer forms where H+ ions can diffuse, creating a charge the level of which is dependent on the pH value of the medium (the potential of this surface is proportional to the pH of the measurement solution).

In order to have a reliable measurement, the inner surface of the sensor’s pH-sensitive layer has to be kept at a stable potential, this way the difference in potential between the two surfaces is only dependent on the pH value of the measurement media. In traditional electrodes this fixed potential is achieved by filling the glass bulb with an inner buffer which maintains a constant pH value.

The X-Chip achieves the same result without any liquid buffer. Instead, it is a composite material with different solid layers. Diffusion bonding ensures perfect adhesion of all layers, and as a result, the X-Chip is mechanically very stable and cannot shatter. As with traditional glass electrodes, the X-Chip design features a reference electrode to enable it to measure pH precisely.

To find out more about this breakthrough technology, email info.mtaus@mt.com, go to mt.com or call 1300 659 761.

^{* The InPro X1 has passed the US military’s MIL-STD-810H drop test.}