HACCP – analysis of dairy products – Part 1: Milk

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Milk is the natural secretion of the mammary gland of farmed animals obtained by one or more milking of healthy animals, to which nothing has been added or taken away. Fresh skimmed milk has a pH of 6.5 to 6.7 and 37 ° C.

After that process, milk goes through treatment. Through all steps of treatment temperature of milk should be closely monitored.

In addition to milk density and composition, the most important observed parameters are tiratable acidity, active acidity and buffer capacity.

Acidity titration should be 6,5 to 7,5°SH, while the active acidity (pH) should be 6,5 to 6,7.

Buffer capacity is the number of moles of acid or alkali required to change the pH per unit.

Temperature is one of the most important parameters in the milk industry. The first critical point occurs after milking the milk when the milk should be taken out of the barn as soon as possible and cooled to the lowest possible temperature (preferably to 4°C or lower) and transport it. the Second critical point arises during the mechanical processing of milk (filtration, fat standardization, homogenization, deaeration). After that the milk should be heat treated (pasteurization process T < 100°C; sterilization process T > 100°C).

Temperature control is important to prevent unwanted overgrowth of microorganisms present in milk and pathogenic bacteria that cause milk spoilage.

The milk industry is a very complex technology with many critical points that need to be strictly controlled. And here are simple solutions to your problems from Hanna Instruments.

Portable Milk pH Meter - HI99162


The Hanna Instruments HI99162 is a durable, waterproof, and portable Foodcare pH and temperature meter designed specifically for milk analysis. Automatic calibration is performed at one or two points with two sets of buffers. All calibration and measurement readings are automatically compensated for temperature variations.

The HI99162 uses the PVDF body FC1013 amplified pH electrode that offers numerous features that improve pH testing for milk producers. The split-level LCD displays both pH and temperature readings, along with indicators for reading stability, battery percentage, and calibration instructions.

The HI99162 uses the FC1013 amplified pH electrode with PVDF body. This specialized electrode offers numerous features that improve pH testing for milk producers. An integrated temperature sensor allows for temperature compensated pH measurements without the need for a separate temperature probe.

Professional Foodcare Portable pH Meter - HI98161

The HI98161 is a rugged, waterproof, portable pH meter that measures pH and temperature using the specialized FC2023 Foodcare pH electrode. This professional, waterproof meter complies with IP67 standards. The HI98161 is supplied with all necessary accessories to perform a pH/temperature measurement packaged into a durable thermoformed carrying case that holds the meters, probes and calibration buffers securely in place.

The FC2023 that is supplied with the HI98161 is designed specifically for measuring pH in food. From a conic tip shape for easy penetration, open junction that resist clogging, and a Polyvinylidene fluoride (PVDF) food grade plastic body that is resistant to most chemicals and solvents, including sodium hypochlorite.

The FC2023 is the ideal electrode to measure the pH of milk, yogurt, meats, cheeses, fruit, sushi, rice, jams, jellies, dough, ice cream, yogurt, beverages, and juice.

Besides being supplied with a unique foodcare pH electrode, the HI98161 has the Hanna’s unique CAL Check™ feature that alerts the user to potential problems during the calibration process. After calibration, the overall probe condition is displayed on screen as a percentage from 0 to 100% in increments of 10%.

The log-on-demand mode allows the user to record and save up to 200 samples that can be recalled or transferred to a PC with Hanna’s HI920015 micro USB cable and HI92000 software for traceability in record keeping for specific product batches.

Mini Titrator for Measuring Titratable Acidity in Dairy Products - HI84529

The HI84529 is an easy to use, fast and affordable automatic mini titrator designed for testing titratable acidity levels in dairy products. Based on an acid-base titration method, this mini titrator uses an optimized pre-programmed method of analysis with a powerful algorithm that determines the completion of the titration reaction by the use of a specialized foodcare pH electrode.

The HI84529 incorporates a precision piston style dosing pump that adjusts the volume of dosing dynamically based on the voltage change. This dosing system reduces the amount of time required for the titration while providing for a highly accurate determination of the amount of titrant used.

The HI84529 uses methods based on AOAC International and Standard Methods for the Examination of Dairy Products. Both of these methods report titratable acidity as % lactic acid and a conversion factor is used to convert the results to the other available units. The HI84529 can be customized to meet the needs of any dairy analysis lab.

There are two fundamentally different measurements of dairy products: titratable acidity and pH.

Titratable acidity is expressed in a variety of units based on the titration method performed. Each method varies in sample size and strength of NaOH used for the titration.

% Lactic Acid (%l.a.): Determined by taking a 20 mL or 20 g sample and diluting with twice its volume with deionized or distilled water. The sample is then titrated with 0.1 M NaOH to a phenolphthalein.

Degree Soxhlet Henkel (°SH): Determined by titrating a 50 mL sample with 0.1 M NaOH to a phenolphthalein.

Degree Dornic (°D): Determined by titrating a 100 mL sample with N/9 NaOH to a phenolphthalein.

Degree Thörner: Determined by taking a 10 mL sample and diluting with twice its volume with deionized or distilled water. The sample is then titrated with 0.1 M NaOH to a phenolphthalein.

Automatic Stirrer
The built-in stirrer is automatically maintained at a speed of 800 rpm for low range titrations and 1000 rpm for high range titrations, regardless of the viscosity of the solution being titrated.

Automatic Potentiometric Titrator - HI932

The HI932 Automatic Titrator is the answer to your dedicated titration needs. Fully customizable, the HI932 delivers accurate results and intuitive user experience, all in a compact package. Titrate for a variety of measurements at the push of a button including acids, bases, redox, and selective ions. No additional programming upgrades to purchase. The only things you need to start using the HI932 are a sensor and titrant.
Multiple Titration Types
Paired with the right electrode, this potentiometric titrator can perform any number of standard titrations including pH and mV tests with fixed endpoints or single equivalence points. By titration in milk you can determine titratable acidity, calcium, calcium direct measure, pH direct measure, salt (NaCl), potassium direct measure, sodium direct measure.
Multiple Measuring Modes
HI932 functions as a potentiometric titrator, pH meter, mV/ORP meter, or ISE meter. 


HALO PVDF Body Foodcare pH Electrode with Bluetooth® - FC2022

The FC2022 HALO is a Bluetooth Smart (Bluetooth 4.0) Foodcare pH and temperature electrode composed of chemically resistant PVDF material.

This electrode has a unique open junction design in which there is a viscolene (hard gel) electrolyte layer that is free of silver chloride (AgCl) between the sample to be measured and the internal reference cell. The open junction design resists clogging and the probe’s conical tip makes it ideal for pH measurements in food products including dairy, dough, ground meats and other semi-solid food samples.

All readings are transmitted directly to the HI2202 edgeblu or a compatible Apple or Android device running the Hanna Lab App.


One Press Connect

Easily connect to the Hanna Lab App at the press of a button via Bluetooth wireless technology.

The FC2022 is revolutionary pH electrode that incorporates Bluetooth Smart (Bluetooth 4.0) wireless technology with an application specific design. This electrode has many features that makes it ideal for measuring food related products. The FC2022 is suitable to use with samples that measure from 0 to 60°C.

The conical shaped tip design allows for penetration into solids, semi solids, and emulsions for the direct measurement of pH in food products including meat, cheese, yogurt, and milk.

HALO pH electrodes can connect with HI2202 edgeblu meter or a compatible Apple or Android device running the Hanna Lab App.

The Hanna Lab App incorporates a probe calibration using up to five pH buffers that are automatically recognized and temperature corrected to 25.0ºC during calibration.

HI700641P Cleaning & Disinfection Solution for Dairy Products (25 x 20 mL Sachets)

The HI700641P is a highly effective cleaning and disinfection solution that is specially formulated for use with pH electrodes that become coated with dairy deposits including milk, cheese, yogurt and ice cream. Electrodes can become dirty from use and will produce inaccurate results even as they read correctly in a pH buffer. Hanna’s cleaning solutions eliminate impurities and residues that are left on the electrode surface after taking measurements of a dairy product. Hanna suggests cleaning the bulb and junction of your electrode on a regular basis to ensure that the probe is always clean and prevent any clogging of the junction.

Each sachet has the lot number and expiration date stamped on it and is made of light block foil ensuring freshness each time one is opened. Hanna’s line of cleaning solutions have been specially formulated to have an expiration of 5 years from the date of manufacture for an unopened sachet.

Digital Refractometer for Brix Analysis in Foods - HI96801

The HI96801 is a rugged, portable digital refractometer for food products designed to report the sugar content of aqueous solutions as % Brix. The HI96801 report the results with an accuracy of ±0.2% Brix. The operation of the meter is simplified with only two buttons: one button is to calibrate with distilled or deionized water and the other to take a measurement. All readings are automatically compensated for temperature variations according to the ICUMSA Methods Book standard and displayed within a 1.5 second response time. The sealed flint glass prism and stainless steel well are easy to clean. Just wipe with a soft cloth in preparation for the next sample.

The HI96801 is ideal for the analysis of fruits, energy drinks, puddings, soy milk, juices, jam, marmalade, honey, soups, jelly, tofu and condiments. The HI96801 is an easy to use tool for measuring sugar in food samples in the field or in the lab.

  • Designed for food sugar analysis
  • Temperature Compensation algorithms based on sucrose solution
  • 0 to 85% brix range with an accuracy of ± 0.2%

Refractive Index

The HI96801 takes measurements based on a sample’s refractive index. Depending on the sample’s composition, light will refract and reflect differently. By measuring this activity with a linear image sensor, the sample’s refractive index can be assessed and used to determine its physical properties such as concentration and density. In addition to the linear image sensor, the HI96801 uses an LED light, prism and lens to make measurement possible.

 Author: Tajana Frančić, mag.nutr.