The Best Ways To Detect Contamination in the Dairy Process

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various dairy products on a table

One of the worst things that can happen to food processing companies is an outbreak of a foodborne illness, which causes a profound loss of consumer trust and, therefore, sales. The incident might also involve grievous legal actions that severely affect your company, leading to financial losses and, in the worst-case scenario, the closure of your company.

As a processor of dairy foods, you should be aware of the potential contaminants in your products and employ prevention and detection strategies that make you feel confident your products are free of harmful pollutants before they hit the shelves. This protects your reputation and your customers’ health.

The following details the types of contaminants you might find in dairy products, where they come from, and the best ways to detect contamination in the dairy process using the latest technology.

What Are the Types of Contaminants Found in Dairy Products?

In dairy products, the contaminants that cause the most concern include microbiological and chemical pollutants. Microbiological contaminants are mainly foodborne pathogens, while chemical toxins include pesticides, herbicides, and antibiotics.

The following are some examples of contaminants that show up in dairy products:

  • Pathogens: campylobacter, listeria, salmonella
  • Hormones: estradiol, testosterone, progesterone
  • Pesticides: diphenylamine, dieldrin
  • Antimicrobial drugs: penicillin, cloxacillin
  • Disinfectants: hydrogen peroxide, benzalkonium chloride
  • Adulterants: melamine, urea, cyanamide

Common Sources of Contamination in Dairy Products

The risk of contamination is present throughout the lifecycle of dairy products, beginning on the farm and continuing through processing and distribution until someone consumes the product. Contaminants can enter products indirectly from the dairy animals’ bodies or directly during processing or packaging.

Pathogens like listeria or salmonella die off in the pasteurization process of dairy products, but they’re still a threat in raw milk, which is legal to sell in some U.S. states.

Microbiological and chemical contaminants come from various sources, including:

  • Pesticides or herbicides in air, water, soil, or animal feed
  • Veterinary drugs (antimicrobials, hormones, etc.) stored in the milk fat of dairy animals
  • Industrial and hygienic practices (metals, sanitizers, detergents, etc.)
  • Additives for improving the quality or yield of dairy products
  • Cross-contamination between raw and finished dairy products

Testing Methods for Detecting Dairy Contamination

samples of dairy products in the laboratory

Considering the broad range of contaminants that can appear in dairy products, it’s essential for processing plants to use an assortment of tests that detect physical, microbiological, and chemical abnormalities.

Depending on the size of the facility, these tests might involve simple laboratory analyses or complex, automated detection systems located at specific control points in the production process.

Physical Testing

Since raw milk can contain dangerous pathogens, dairy processing facilities perform tests on the physical properties of the milk before accepting it, including checking its appearance, odor, temperature, and acidity.

Testing methods for checking the physical qualities of dairy products include organoleptic (smell, taste, and visual observation) tests, lactometers, and the Gerber method.

Microbiological Testing

Processing plants often use traditional culture-based testing to detect pathogens in dairy samples, but they can also incorporate automated and rapid testing methods to detect the contamination of bacteria in the product. Systems with built-in microscopes, centrifuges, and other technologies can separate samples and determine the bacterial count in minutes.

Tests for microbiological hazards include lateral flow tests, polymerase chain reaction (PCR) detection, and air monitoring systems.

Chemical Testing

One of the most prevalent detection methods for chemicals, including pesticides, is mass spectrometry, a technique involving the ionization of a sample to identify the chemical compounds it contains, including how much of each chemical is present. Liquid and gas chromatography are also common techniques for separating samples into parts for examination.

What Are the Risks Associated With Consuming Contaminated Dairy Products?

woman having stomachache because of consuming contaminated dairy products

Consuming contaminated dairy products, especially unpasteurized milk, poses serious health risks. In the U.S., 96% of outbreaks linked to dairy consumption are due to contaminated unpasteurized milk and cheese products, meaning unpasteurized products cause 840 times more illnesses than pasteurized products.

Illnesses from contaminated dairy products are mostly caused by infections from listeria, salmonella, E. coli, and other pathogens.

Someone with a foodborne illness might experience symptoms such as:

  • Fever
  • Nausea
  • Vomiting
  • Diarrhea
  • Abdominal pain
  • Headache
  • Body aches

While people with strong immune systems will likely recover quickly, someone with a weakened immune response could experience severe symptoms and potentially develop life-threatening complications. Pregnant women might pass the infection to their unborn babies, leading to serious illnesses or complications like premature birth.

Preventative Measures for Detecting Dairy Contamination

Testing for dairy contamination is a safety net that ensures products potentially dangerous for consumers don’t make it to retail stores, while preventative measures help keep the hazards out of the product in the first place.

Milk pasteurization is one of the best-known techniques for making dairy products safe to consume. Still, dairy processors use many other control measures to keep impurities out of their products.


A Hazard Analysis and Critical Control Points (HACCP) plan helps manufacturing facilities control food safety hazards and, ideally, prevents contaminants from entering their products. The plan involves identifying potential physical, chemical, or biological hazards and establishing critical control points (CCPs) where control measures are necessary to keep contaminants out of the product.

An HACCP plan for companies that produce dairy products might include control measures like:

  • Milk pasteurization
  • Cleaning and sanitizing storage tanks
  • Controlling the presence of chemicals on and around processing equipment
  • Animal drug residue testing
  • Monitoring vitamin A and D levels
  • Using a filter to block physical contaminants

Good Manufacturing Practices

Measures you can take to control contamination from farms to dairy processing facilities include:

  • Adequately sanitizing the surrounding environment
  • Separating sick and healthy dairy animals
  • Follow Good Manufacturing Practice (GMP) guidelines for milking, storage, etc.

Good manufacturing practices for dairy products include ensuring milking and processing equipment get proper sanitization, keeping milk in cold storage at 40 degrees, and separating raw dairy from finished products.


Part of a good manufacturing process is cleaning and sanitizing equipment to eliminate bacteria and leftover dairy products from farm or plant surfaces. Excess residue from cleaning chemicals like detergents and disinfectants can get into the product due to improper cleaning procedures.

While small amounts of contamination from sanitation chemicals don’t appear to be harmful to people, other environmental pollutants might carry higher health risks. Practicing proper hygiene procedures reduces the risk of significant levels of adulteration in dairy products.

Importance of Training and Education in Detecting Contamination in the Dairy Process

production manager instructing trainee at dairy production

Food safety training is critical for preventing food poisoning and other health risks caused by contaminated dairy products. Workers in a dairy processing plant should be aware of the hazards that could occur where they work and know the proper ways to handle products and equipment.

The benefits of food safety training and education include:

  • Reduces food waste
  • Builds trust with customers
  • Increases processing efficiency
  • Ensures legal compliance

Keep Contaminants Out of Your Dairy Products With TDI Packsys

At TDI Packsys, we understand how vital it is to detect contamination in the dairy process and ensure your products are safe for consumption. Our state-of-the-art food inspection systems are specially designed to detect physical hazards in a wide variety of dairy products.

For more information on our food processing detection systems, contact us at 877-834-6750.

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