Dairy Laboratory Analysis Equipment for Quality and Production

Dairy Science

Open your lab to the possibilities.
What do you want to analyze today?

Milk and dairy products are some of the most controlled foodstuffs in most countries. From the producer to the finished product, the process is monitored, logged, and analyzed every step of the way. Food safety and quality are primary drivers behind consumer decisions, determining the overall success of food and beverage suppliers. At Xylem Lab Solutions, our goal is to support you with innovative laboratory instrumentation that will help deliver safe and high-quality products every time. From nitrogen to sugars, start to finish, and everything in between, we have solutions to meet your analysis needs. Backed by over a century of providing lab instrumentation to the food and beverage industry, you can rest assured knowing you have a team of experts supporting your analyses.

ProteinTotal Fat NitrogenAcidity/pHLactose/SugarsDairy EffluentMoisturePesticides  |  Salt  

dairy science analysis applications


dairy analysis

Elemental Bifurcation

Few elements are more fundamental than nitrogen; its abundance is essential for the expansion of industry, the air which we breathe, the very way we maintain our existence as life on Earth. Nitrogen, the genetic information carrier, the building block of amino acids, 78% of the atmosphere, highly regulated colorless/odorless gas, whatever you want to call it... is everywhere.

The way we interact with nitrogen has changed dramatically in the last century. Widespread adoption of fertilizers, pesticides, and industrial-grade chemical compounds have increased crop yield, advanced chemical production, and burgeoned human dominance in a nearly logarithmic fashion. However, there is a duality to nitrogen that parallels the Shakesperean idiom “Why then, can one desire too much of a good thing?” The ratio of oxygen to nitrogen in our atmosphere is amazingly precise, as pure nitrogen gas will cause asphyxiation. The addition of one oxygen atom to two nitrogen atoms produces nitrous oxide, which renders people delusional when inhaled once, and psychotic when abused over time. Not to mention, excess runoff from waste, fertilizers, and nitrogen compounds such as ammonia and nitrate can cause harmful algal blooms and lake eutrophication in the environment. This last point explains why nitrogen compound concentration is monitored in municipal and industrial effluent, but where else is nitrogen measured in dairy product manufacturing specifically?

nitrogen cycle dairy analysis

The Basics

There is one key ingredient that links all dairy products together: Milk. And, of course, there is one creature that is responsible for most of the milk production in the world: The Cow!

dairy analysis cow

Cows (and goats) need to eat well in order to routinely produce quality milk. Feed is therefore measured for moisture, fiber, energy, and protein. Amino acids, proteins, and nucleic acids are all made of organically bound nitrogen and are critical to both the metabolism and structure of living organisms. Since the nitrogen (N) content in protein is on average around 16%, a calculation of 6.25 x N originally was used to determine Crude Protein. However, researchers determined that 6.25 was not specific enough because nitrogen content varies by food, and now several “Jones factors” have been established (6.38 for milk). To learn more about protein analysis, click the protein section at the top of the page. Before you go let’s first understand how nitrogen is measured, so further analysis of parameters such as protein can occur!

How is Nitrogen Measured?

The Kjeldahl method is the most dominant and universal reference method to measure nitrogen. The original Kjeldahl method is now more commonly referred to as Total Kjeldahl Nitrogen (TKN) analysis, which is a measurement of the proportion of total bound organic nitrogen and ammonium. There is also Total Nitrogen (Total N) analysis, which is a modified version of the original Kjeldahl method that includes nitrite and nitrate. TKN analysis is done in many regulated industrial applications including food and beverage, fertilizers, effluent, and more.

There are several international standards by which nitrogen is measured in dairy products. One such standard is ISO 8968-1:2014 | IDF 20-1:2014, which describes nitrogen and crude protein determination by the Kjeldahl principle, using traditional and block digestion methods. This is applicable for cow's (whole, partially skimmed or skimmed) milk, goat's and sheep's whole milk; hard, semi-hard and processed cheese; dried milk and dried milk products, milk protein concentrate, whey protein concentrate, casein and caseinate.

Gerhardt offers a solution to full automation of TKN measurement, allowing for improved safety and higher throughput with the KJELDATHERM block digestor and the VAPODEST steam distillation series of products. The Dumas method for nitrogen (protein) analysis with the DUMATHERM combustion system allows for up to 140 samples per 8-hour shift to be analyzed. These comprehensive laboratory platforms are extremely efficient and make for a quick return on your investment.



Another international standard is ISO 14673-3|IDF 189-3:2004, which specifies a routine method for the determination of the nitrate and nitrite contents of milk and milk products by cadmium reduction and flow injection analysis (FIA). The method is applicable to hard, semi-hard and soft cheeses of various ages, and processed cheese.

The FS3700 by OI Analytical is the ultimate flow analysis platform, with validated methods in many industries including nitrate/nitrite analysis following ISO 14673-3. This modular, high-throughput, automated chemistry analysis system is an affordable alternative to conventional techniques that will save you time, money, and effort. As our fourth-generation flow analyzer, this dependable technology will provide dependable results every time.

OI Analytical Flow Solution
3700 Automated Chemistry Analyzer



dairy protein analysis

Proteins are composed of amino acids, “chemical building blocks” and are a critical component in the diet of both humans and animals.  Protein supports the creation and maintenance of every cell in the body and knowing the amount of protein in your dairy product is a crucial measurement for assessing food quality and considered one of the 5 critical parameters (fat, sodium, water, protein, and fiber).

The protein content is calculated from the determined nitrogen result in your sample using a nitrogen conversion factor and is a decisive criteria for the quality and price of a product. 

The two major methods for measuring nitrogen are Kjeldahl and Dumas, both of which are used in milk and milk products.  The Kjeldahl method relies on strong acids, heat, and catalysts, followed by distillation, while the Dumas method relies on combustion making it 70X faster.  A variety of methods for dairy products name both or either principle such as ISO 14891|IDF 185:2002 nitrogen content according to the Dumas principle, while ISO 8968, IDF 20 and AOAC 991-20 nitrogen content according to Kjeldahl. 

Xylem offers both solutions for your nitrogen/ protein analysis in the KJELDATHERM/VAPODEST or the combustion analyzer the DUMATHERM.




Humanity has been confronting the challenge of pests, weeds, and diseases since the dawn of the practice of agriculture. Interestingly, the first recorded evidence of pesticide use dates back around 4500 years ago, when the Sumerians used sulfur compounds to control various insects and mites. Since the discovery and use of organochlorides like DDT, and other nerve agents during the Second World War, pesticide use has increased so much that some historians refer to this period as the dawn of the Chemical Age. However, the harmful side effects of pesticide use became well documented after the anti-chemical and anti-pesticide movement of the 1960s and the creation of the Environmental Defense Fund.

dairy measurement pesticides

Regulation and Monitoring

Although pesticide use has continued to grow with increasing food supply and demand, pesticides are now heavily regulated in both the United States and around the world. The dairy industry is one of particular importance due to the variety of pesticides used in animal feed. Many pesticides such as organochlorine, organophosphate, synthetic pyrethroid and triazine have been found in milk, milk powder products, yogurts, cheese, butter, and sour cream. Organochlorine pesticides are environmentally stable and lipophilic, causing them to readily accumulate in milk fat. In dairy product manufacturing, pesticide levels are most commonly measured via gas chromatography (GC) and/or mass spectrometry (MS). USDA, FDA, and EPA all have programs designed to monitor pesticide residue, in both multi-residue and highly selective forms. USEPA Method 608.3 describes a method for the determination of organochloride pesticides from industrial discharge using gas chromatography (GC) with a halogen-specific detector (HSD).

OI Analytical offers the 5360A XSD, a halogen-selective detector for gas chromatography systems that is specifically designed to respond to chlorinated pesticides, reducing the need for sample preparation. This detector is designed for use on most GC models and comes equipped with a venting option that diverts solvent before entering the reactor.


Measuring total fat in dairy products is also a crucial measurement for assessing food quality and considered one of the five critical parameters measured in food. Multiple AOAC methodologies exist for various matrices that incorporate acid or alkaline hydrolysis to accomplish total release of fat from various products followed by total fat extraction by mixed ethers.

These AOAC methodologies are labor intensive with variations in reproducibility across matrices.

The HYDROTHERM is an automated, fully enclosed acid hydrolysis system by the ISO 8262-3 | IDF 124-3:2005 Weibull-Stodlt/Berntrop gravimetric method. Paired with the SOXTHERM a 5-stage rapid extraction system that combines the benefits of the traditional Soxlet and Twisselman methods,  to automate your total fat analysis.

total fat measurement dairy


dairy measurement total fat analysis



Determining lactose and other sugars in dairy products is routine with a variety of methods. For example, measuring lactose is important in dairy products as it relates to quality, manufacturing efficiency and product properties. From polarimeters, refractometers to measure Brix, and biochemistry analyzers, Xylem Lab Solutions offers instrumentation designed specifically for determining lactose and other sugars in dairy products.

Polarimetery is a classical way to measure lactose in dairy products, AOAC Method 896.01 has been used since 1896.

Lactose has asymmetric carbon centers, giving it chirality, and making it optically active. Polarimetry can be used to determine lactose concentration using the optical rotation measured from a sample. This is a primary research method. However, it is not specific to lactose because other compounds that are optically active in the sample being studied can influence the rotation measurement. It is not used often to quantify lactose, because there are newer and better methods, however, to determine the anomer composition of lactose, polarimetry remains a widely used method.

The ADP 450 Polarimeter with Peltier temperature control, 21 CFR Part 11, low maintenance LED light source make it a perfect choice for measuring the anomer composition of lactose.

When a brix measurement is what you are after refractometers are simple but effective instruments which use the speed of light passing through a sample to determine the "refractive index". The refractive index is related to the sample density and hence the concentration (total dissolved solids).

Simple refractometers to test for milk adulteration at point of collection at the farm or in the factory as well as for checking the °Brix" of sweet additives such as fruit syrups for yogurt production.

Optical refractometers are great for homogeneous samples but when it comes to foodstuffs that are made of emulsions containing fatty compounds, such as dairy products (milk and yogurt for example) that cause the light to scatter, the borderline cast onto the refractometer scale of an optical instrument becomes blurred. This makes it difficult for the human eye to determine a finite reading. This is where digital refractometers come in.

The digital refractometer RFM 340T becomes a great tool for quality control checking yogurt and other non-homogenous food samples where optical refractometers are not so easily used; offering food producers a quick and easy method of controlling non-homogenous product during manufacture and beyond.

Lactose concentrations in complex matrices such as cheese can be measured directly and quickly using the YSI 2900 Series Biochemistry Analyzer. Measurements are virtually unaffected by color, turbidity, density, pH, or the presence of reducing substances. In addition, there is a complete suite of sugar measurements that are compatible with the 2900 system, including Glucose, Glutamate, and Galactose.

lactose measurement dairy quality control

 RFM 340T and  ADP 450 Polarimeter

lactose sugar measurement dairy

YSI 2900D


The titratable acidity test is employed to ascertain if milk is of such a high acidity as to reduce its keeping quality and heat stability. The acidity of milk is of two kinds:

  • i. Natural acidity which is due to citrates and phosphates present in the milk and dissolved CO2 during the process of milking and thereafter. 
  • ii. Developed acidity which is due to lactic acid produced by the action of bacteria on lactose in milk.

Generally, the acidity of milk means the total acidity (Natural + developed) or titratable acidity. Classically, acidity has been determined by titrating a known volume of milk with standard alkali to the point of an indicator like phenolphthalein. Using the TitroLine series of autotitrators allows for automated and repeatable determination of total acidity in milk, all without the use of indicators. 

The MultiLab 4010-3W is a quick and easy way to know the pH of milk products. The Science pHT-G features a ground joint junction with a relatively fast outflow of electrolyte (~ 3 mL per day). This fast outflow helps keep the junction clear, which makes the Science pHT-G electrode suitable for measurements in solutions with a lot of suspended particles.

ph acidity measurement dairy milk

Multilab 4010-3W

dairy milk acidity ph measurement

YSI TitroLine 7000


Measuring sodium chloride in milk and other dairy products is important. Sodium chloride is added to milk with the aim of increasing the density as well as the ash content which has been adulterated with water. Food labs also need to quantify the concentration of salt in cheese and other dairy products.

Automatic titrators can quickly and easily determine the amount of salt in liquid products and products that can be homogenized into a solution (such as cheese). Titration can be performed on products even if they are still warm from processing.

The Titroline autotitrators provide a simple and repeatable way to measure salt content from practically any dairy product, in a fraction of the time it would require if using traditional manual titration methods.


Accurate moisture measurements are critical in powdered milk products. Due to the highly hygroscopic nature of amorphous lactose in milk powders, moisture measurements are important. Moisture uptake in the milk powders can cause lumps and crystallize changing the flavor and taste. Legal and safety reasons also need to be considered. Making precise and accurate measurements of water in the finished product with Karl Fisher titrators can measure as low as 1ppm.




Minimizing waste is an important part of any effort, especially in large scale production facilities. Because milk is almost 90% water, dairy processing factories can reuse this water when they make more concentrated milk products. This water is called condensate of whey (abbreviated as COW, ironically enough) water, with whey being the byproduct liquid after milk has been curdled or strained. For COW to be reused (in any application), it must pass significant water quality testing, and abide by the standards set forth in the FDA’s Federal Grade-A Pasteurized Milk Ordinance.

dairy effluent analysis

Preventing Excess During Exits

The last area to monitor nutrients in dairy product manufacturing is in the effluent. Like any industrial application, the water that returns to our environment must be measured for sources of contamination according to international standards and regulatory guidance. The fastest way to non-specifically determine water quality is via total organic carbon (TOC) analysis.

OI Analytical offers several laboratory TOC analyzers including the 1030W, 1030D, and 1080 to meet all your analysis needs. For more information on how TOC analyzers work, visit the TOC parameter page.

Our laboratory experts are available to help with everything from instrument selection to application support for various applications

YSI, OI Analytical, and the rest of our Xylem Lab Solutions brands are excited to offer free virtual consultations for your next facility project or upgrade. Our dedicated team of application engineers and experts identify the best technology for your needs.

dairy laboratory analysis