Overview: Milk processing turbidity and pH measurement helps dairies reduce product loss, lower BOD charges, and ensure compliance with 3A and EHEDG standards. Glass-free ISFET pH probes with Memosens connectivity and wide-range turbidity sensors provide accurate, low-maintenance monitoring across raw milk reception, fermentation, and product changeovers.
The Cost of Inaccurate Measurement in Milk Processing
Milk processors face two constant challenges: controlling pH throughout production and managing product-to-water transitions during line changes. When pH sensors drift or when phase changes are judged by timers and sight glasses, the result is wasted product, excess water and chemical use, and higher wastewater surcharges.
Inline measurement offers a way to eliminate those inefficiencies. Four technical requirements define sensors fit for use in dairy:
- Glass-free pH measurement
- Digital connectivity
- 3A/EHEDG hygienic certification
- A wide turbidity measurement range
Glass-Free pH Measurement
Traditional glass electrodes present two problems in milk processing. First, even a small fracture can stop production and risk contamination. Second, milk proteins tend to coat glass diaphragms, causing measurement drift or sensor failure.
Glass-free ISFET (Ion-Sensitive Field Effect Transistor) probes address both issues.
- Unbreakable design: eliminates risk of glass fragments in product
- Resistance to fouling: ISFET probes continue to provide stable readings even in viscous dairy media such as yogurt or cream
- Stability under CIP/SIP: withstand high temperatures and cleaning cycles without significant drift, often holding calibration for weeks at a time
Accurate pH monitoring is particularly important during fermentation, where the endpoint (pH 4.5–4.7) determines the acidity and consistency of yogurt. Inline ISFET probes provide reliable readings at that stage without the risks of glass electrodes.
Case example: A yogurt producer relying on glass electrodes faced frequent recalibration and sensor failure due to protein fouling. Replacing glass with solid-state pH probes stabilized fermentation control and reduced downtime, ensuring consistent acidity without risk of glass contamination.
Memosens Digital Connectivity
The second requirement is connectivity. Conventional cable connections are vulnerable to moisture, especially in dairy plants where washdown is routine. Cable corrosion or noise can lead to unreliable signals and downtime.
Memosens digital technology replaces direct electrical contact with inductive, contactless transmission:
- Moisture resistance: no failures due to humidity or water ingress
- Data retention: calibration and diagnostic information stored in the sensor itself, enabling calibration in a controlled lab environment rather than on the plant floor
- Predictive maintenance: stored history allows trending of sensor performance for proactive replacement
- Plug-and-play replacement: transmitters automatically recognize a new sensor when connected, reducing downtime
In whey processing, ISFET probes with Memosens connectors maintained accuracy through more than 300 CIP cycles and required calibration only every six to 12 months.
3A and EHEDG Certification
Sanitary certification is a third defining requirement for any inline instrument in dairy. Sensors must withstand repeated sterilization, resist bacterial growth, and use only approved wetted materials.
- 3A certification confirms that designs comply with U.S. dairy industry sanitary standards, including fully cleanable Tri-Clamp connections.
- EHEDG certification ensures compliance with European hygienic design requirements, covering CIP/SIP cleaning to 140 °C for up to 120 minutes.
- Wetted parts made from FDA-compliant stainless steel and sapphire glass further support hygienic assurance.
Without these certifications, sensors introduce risk of contamination and require additional validation work. Certified designs assure processors that instruments are fit for direct contact with milk and finished dairy products.
Wide Turbidity Range Capability
The final requirement is a turbidity sensor capable of monitoring across the full range of dairy applications — from clear rinse water to high-fat cream.
Why turbidity matters:
- Phase separation: determines the exact point when milk has been flushed out and water begins, or when water is fully displaced by cleaning solution
- Product recovery: prevents good product from being diverted to drain during changeovers
- Wastewater management: reduces biological oxygen demand (BOD) surcharges by diverting high-load streams away from the main effluent
Older methods create inefficiencies:
- Timers do not account for changes in viscosity, temperature, or system pressure.
- Sight glasses rely on operator judgment, which can be inconsistent.
- Conductivity misreads caustic solutions, leading to unnecessary diversion of water to the treatment plant
The Real-World Impact of Turbidity Sensors
Published application studies in the dairy industry illustrate the cost of relying on those legacy methods. In one facility, time-based flushing meant that roughly 15 gallons of milk and 20 gallons of water were lost on every cycle. When the plant replaced timers with inline turbidity monitoring, the investment was recovered in just three weeks.
In another case, a dairy reduced municipal sewage charges by 15% within three months of adopting inline turbidity measurement, simply by diverting high-load wastewater before it reached the main effluent stream. Medium-sized dairies processing several hundred thousand pounds of milk daily have reported six-figure annual savings from the same approach, driven by both product recovery and reduced BOD surcharges.
Glass-Free ISFET pH Probes with Memosens Connectivity
Glass-free ISFET pH probes eliminate the risk of glass breakage in milk processing and avoid the protein fouling that causes conventional electrodes to drift. When equipped with Memosens, they provide:
- Moisture-proof signal transfer with inductive, contactless transmission
- Stored calibration and diagnostic data, allowing probes to be calibrated in the lab instead of on the plant floor
- Predictive maintenance, based on diagnostic history embedded in the sensor
- Plug-and-play replacement, with automatic transmitter recognition
For convenience, ISFET probes can be installed in EXtract sanitary retractable housings, which are 3A- and EHEDG-certified and withstand repeated CIP/SIP cycles. This configuration allows probes to be inserted or removed for maintenance and inspection without stopping production, ensuring reliable pH control during fermentation, storage, and raw milk reception.
Exner EXspect Turbidity Sensors
Exner’s EXspect turbidity sensors address the wide measurement range required in dairy applications, from clear rinse water through high-fat cream.
Specifications:
- Measurement range: up to 300,000 NTU (≈75,000 EBC)
- Response time: sub-second detection of phase changes
- Reproducibility: better than 1% of full scale
- Construction: stainless steel body with sapphire optics for durability under CIP/SIP
- Hygienic assurance: 3A-certified and EHEDG-tested, with Tri-Clamp and other process connections
Application benefits in milk processing:
- Detecting milk-to-water and water-to-cleaning solution transitions without timers or relying on operator judgment
- Reducing drain losses during product changeovers;Â case studies show payback in weeks
- Diverting high-load wastewater before it reaches the main effluent, lowering BOD surcharges
- Supporting hygienic operation, withstanding sterilization up to 140 °C for 120 minutes
South Fork Instruments distributes Exner EXspect turbidity sensors in the Americas. In addition to turbidity, South Fork provides a full portfolio of pH instrumentation to address the broader requirements dairies face, including glass-free operation, digital connectivity, and hygienic certification. Together, these offerings give processors the tools to reduce losses, control wastewater costs, and maintain compliance.
From Inefficiency to Measurable Gains
Milk processors that continue to rely on timers, sight glasses, or glass electrodes accept losses that can be avoided. Inline measurement provides a direct path to reducing product waste, controlling water and chemical use, and simplifying compliance. South Fork Instruments supplies glass-free ISFET pH probes with Memosens connectivity and Exner’s EXspect turbidity sensors, both engineered for hygienic dairy applications. Together, these solutions align with 3A and EHEDG requirements while delivering reliable, low-maintenance performance.
Contact South Fork to discuss how inline turbidity and pH measurement can reduce losses in your milk processing plant.
Read More
