What are Common Adulterants in Milk and How to Detect Them?

Adulterants in Milk

Milk, renowned for its nutritional richness and versatility, is a dietary staple for millions worldwide. However, the trustworthiness of this essential food source is frequently jeopardised by a practice known as adulteration. 

This deceitful act involves adding substances to milk, often to increase its volume, alter its composition, or enhance certain characteristics. Adulteration of milk not only poses grave risks to consumer health and erodes confidence in the dairy industry.

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What is Milk Adulteration?

Food Adulteration is the willful act of lowering the quality of offered food by mixing or substituting it with substandard substances or removing mandatory components. This statement also applies to milk.

Infection of foodstuffs happens during the period of harvest, growing up, preservation, transportation and distribution. However, these two words are not synonymous when it comes to milk. Milk adulteration is the process of adding substances like water, urea, or detergent to milk, compromising its quality and nutritional value, often for economic gain, posing health risks.

When is Milk Considered Adulterated?

Milk is considered contaminated when mixed with substances not permitted or approved for use in milk products. Adulteration of milk can occur through various means.

If any of the following situations apply, milk is deemed contaminated. 

  • Addition of compounds with potential health effects

  • Elimination of a necessary nutrient entirely or in part

  • Partial or complete substitution of inferior materials for nutrients

  • Additional factors that could cause the quality to fall short of expectations 

Many people are very worried and puzzled by the increasing milk adulteration motivated by the love of money in India. Milk collection and testing practices across the nation have yet to comply with the guidelines of the Food Safety and Regulation Authority of India (FSSAI). This situation is far beyond what could be imagined.

What are the Common Adulterants in Milk?

Understanding the many compounds that dishonest people could add to milk to trick consumers or boost earnings is necessary to introduce the common contaminants in milk.

Milk adulteration is a major problem worldwide, and those who engage in it use various substances to dilute or change the content of milk. Here are 9 common adulterants in milk, of which everyone should be aware:

1. Water

The most popular adulterant is water. Typically, water is added to milk to make it more volumetric, diminishing its nutritional value. Contaminated water can infect milk, posing a major health risk.

2. Urea

Urea is a nitrogen-containing compound sometimes used as an adulterant in milk. Its addition to milk constitutes adulteration and poses significant health risks when consumed excessively.

3. Sucrose

To increase the density of milk, sucrose is typically added. Sucrose, commonly known as table sugar, is one of the adulterants that unscrupulous individuals may add to milk to increase its sweetness or enhance its flavour.

4. Starch

Another typical adulteration in milk is starch. Starch is added to increase the density of milk, making it harder to find evidence of unnecessary water added to it. The human body may experience diarrhoea after consuming starch.

5. Glucose

To raise the lactometer reading, glucose is added. It offers flavour as well. For those with diabetes, glucose of poor quality is detrimental.

6. Hydrogen Peroxide

To enhance the quality of milk, hydrogen peroxide is added. It keeps milk fresher for longer. The digestive tracts are adversely affected by hydrogen peroxide. It could result in inflammation and gastritis.

7. Maltodextrin

Maltodextrin is a common addition to milk, increasing the volume of milk and milk products. Drinking milk tainted with maltodextrin might result in allergies and diarrhoea.

8. Salt

To increase the density of milk and hide the presence of additional water, sodium chloride, or salt, is added. Drinking milk tainted with salt is not recommended for those with high blood pressure.

9. Neutralisers

Neutralisers, such as carbonates and alkali bicarbonates, are added to milk to counteract the acquired acidity. However, neutralisers do not improve people's health; they can cause gastrointestinal problems.

What is the Difference Between Milk Adulteration and Contamination?

Despite their many differences, adulterating and contaminating milk have detrimental health impacts. See the table below to gain a better understanding.

Milk Contamination

 Milk Adulteration
The term "milk contamination" describes the process of declining material quality. "Milk adulteration" describes adding certain lawfully allowed compounds to milk.
This can occur organically or due to numerous environmental factors, including heat, humidity, etc. Artificial factors are the reason behind this. This is a profitable technique carried out by merchants or businesspeople.
Detection methods include microbiological testing, chemical analysis, and sensory evaluation to identify harmful contaminants. Requires specialised laboratory tests and analytical techniques to identify and quantify contaminants accurately.
It can lead to foodborne illnesses, infections, toxicity, or other adverse health effects. If consumed, depending on the type and concentration of contaminants present. Depending on the nature of the adulterants, it may pose health risks due to the addition of harmful substances, such as toxins, allergens, or chemical residues.
It can occur due to unsanitary conditions during milk production, processing, or storage, leading to microbial growth or chemical contamination. To increase volume, mask quality deficiencies, or enhance certain properties of milk.
Contaminants may include pathogenic bacteria (e.g., Salmonella, E. coli), antibiotics, pesticides, heavy metals, and toxins from environmental sources. Adulterants such as water, urea, starch, sugars, and synthetic chemicals may be added to milk.
It is unintentional and often unavoidable, typically due to environmental contamination or improper handling. Intentional and deceptive acts aimed at deceiving consumers and maximising profits.

How to Check Adulteration of Milk at Home?

Consumers often need help in identifying contaminated or adulterated milk. Fortunately, several simple yet effective methods can be employed at home to detect potential adulterants and assess milk quality.

Adulterants

 Ways to Detect
Water Participants in this test must aim for a milk drop at any slanted surface. Pure milk will flow slowly and leave a trace; thus, if it flows quickly, it must contain water. There will undoubtedly be no trace of tainted milk.
Starch Boli 2 to 3 millilitres of milk with 5 millilitres of water. Once it cools, add 2 to 3 drops of iodine tincture. If the mixture turns blue, it has starch in it.    
Urea The taste of milk remains unchanged, and it is difficult to identify the presence of urea. As a result, people must combine a tablespoon of milk with soybean powder and shake thoroughly to determine whether the milk they drink daily contains urea. 
 
They must then dip a litmus paper for a brief period. The sample contains urea if the colour shifts from red to blue.
Detergent Many detergents are used to degrade milk. To determine whether detergent is present in milk, people must shake 5–10 millilitres of milk well with equal water at home. 
 
If they observe that mixing milk and water creates a thick foam, it indicates possible adulteration in milk. Pure milk forms a thin film of foam.
Synthetic Milk Synthetic milk may taste a bit more bitter than pure milk. When you rub the synthetic milk between your fingers, the texture of the liquid becomes soapy, and when you heat the synthetic milk, it starts turning yellow.    

Laboratory Methods to Test Milk for Adulteration

These sophisticated analytical techniques, conducted in accredited laboratories by trained professionals, provide reliable milk quality and authenticity assessments.

Adulterants

 Laboratory Test
Vanaspati Lab workers must add three millilitres of milk, ten drops of hydrochloric acid, and one tablespoon of sugar to a test tube. After five minutes of resting the mixture, they must check for colour changes. If the combination becomes red, vanaspati is present in the milk.
Formalin Lab personnel must add 10 millilitres of milk to a test tube. Next, they must carefully pour 5 millilitres of concentrated formalin out the side of the test tube wall. The acid must be properly poured without being shaken. 
A reddish-purple ring formed at the interface between two layers indicates the presence of formalin in the mixture.
Hydrogen Peroxide To specifically detect hydrogen peroxide during a milk adulteration lab test, lab personnel will fill a test tube with three drops of para phenylene diamine and five millilitres of silver nitrate reagent.
They will then thoroughly shake the mixture. The milk includes hydrogen peroxide if the hue turns blue.
 
Salt To find salt in milk, laboratory professionals place 5 millilitres of silver nitrate reagent in a test tube and add two to three drops of the potassium dichromate reagent. 
They will then add one millilitre of milk and thoroughly mix it. There is salt present if the mixture becomes yellow.
Boric Acid Lab workers will take 3 millilitres of milk and put 20 drops of hydrochloric acid in a test tube to determine whether or not the milk contains boric acid. They will then give the mixture a good shake. They will dip a yellow paper strip in the mixture and let it sit for a minute. 
After adding one drop of ammonia solution, milk contains boric acid if the combination changes from red to yellow and then back to green.
Ammonium Sulphate Lab workers must fill a test tube with heated milk (5 millilitres) and citric acid to finish the lab testing of tainted milk. The generated whey will then be separated and filtered.
Subsequently, they must transfer the whey to an additional test tube and incorporate 0.5 millilitres of 5% barium chloride. Precipitate in the test tube is a sign that ammonium sulphate is present.

Harmful Effects of Milk Adulteration

Indians cannot live without milk, especially during festivals, because it is used to make sweets. However, when they can't get pure milk from retailers due to such high demand, this gap is bridged by adding other things to pure milk, adversely affecting its quality.

The negative effects of tainted and adulterated milk are listed below.

  • Kidney Issues: Adulterants like urea added to increase the apparent protein content of milk, can be toxic to the kidneys. Consumption of milk adulterated with urea can lead to kidney damage or exacerbate pre-existing kidney conditions, potentially causing kidney failure or other renal issues.
  • Heart-Related Issues: Adulterants such as vegetable oil and other fatty substances added to milk can elevate unhealthy fats and cholesterol levels in the bloodstream. Prolonged consumption of contaminated milk may increase the risk of heart-related issues such as atherosclerosis, hypertension, and coronary artery disease.
  • Organ Malfunctioning: Toxic substances like formalin, used as a preservative in milk adulteration, can have adverse effects on various organs in the body. Formalin exposure may lead to liver damage, respiratory issues,  and other forms of organ malfunctioning, particularly with chronic exposure.
  • Low Vision: Contaminants such as heavy metals or toxins from environmental sources, if present in adulterated or contaminated milk, can harm vision health. Chronic exposure to heavy metals like lead, mercury, or cadmium through contaminated milk consumption may lead to vision problems, including vision loss or impairment.
  • Cancer: Certain pollutants and contaminants in milk, such as pesticides, hormones, or chemicals from environmental pollution, have been linked to increased cancer risk. Prolonged exposure to these carcinogenic substances through the consumption of adulterated or contaminated milk may elevate the risk of various types of cancer. 
  • Death: In severe cases, consumption of adulterated or contaminated milk can lead to fatal outcomes. Toxic substances, pathogenic bacteria, or other harmful contaminants present in adulterated or contaminated milk can cause acute poisoning, severe foodborne illnesses, or systemic organ failure, ultimately resulting in death.

Milk adulteration poses significant risks to consumer health and undermines trust in the dairy industry. Strict regulatory measures, quality control standards, and public awareness campaigns are essential to detect and prevent milk adulteration, ensuring the safety and integrity of dairy products.

Consumers play a vital role in safeguarding their health by purchasing milk from reputable sources, being vigilant for signs of impurity, and advocating for transparent and ethical practices in the dairy industry.

FAQs about Milk Adulteration