Milk and milk products testing

Milk is produced by mammary glands and is the preferred food for infants during the development and maturation of their digestive tracts. Milch animals like cow, goat, buffalo, and sheep are the most common global milk producers. ⁽¹⁾ Dairy products have been a staple of human nutrition for several years which includes cheese, yoghurt, ice cream, and butter. ⁽²⁾

Composition of Milk

Nutritional Importance

Milk and milk products have appropriate protein, fat, and carbohydrate balance and are an important source of essential nutrients such as calcium, riboflavin, phosphorous, vitamins A and B₁₂, potassium, magnesium, zinc, and iodine are all found in foods. Milk contains "essential proteins" that are well suited to human needs. For example, mixing milk (or yoghurt) with cereal can provide amino acids that the cereal product may lack. ⁽³⁾

Milk Products and their Characteristics ⁽⁴⁾

Liquid Milk: Liquid milk is consumed, processed, and marketed the most. Pasteurized milk, skim milk, standardised milk, reconstituted milk, ultra-high-temperature (UHT) milk, and fortified milk are all examples of products that fall under the category of liquid milk.

Fermented Milk: Fermented milk is frequently used in the production of other milk products. They are made by fermenting milk with appropriate microorganisms to achieve the desired level of acidity. Yogurt, koumiss, dahi, labneh, ergo, tarag, kurut, and kefir are examples of fermented dairy products.

Cheese: Cheese is made by coagulating milk protein (casein), which is separated from the whey in milk. Hundreds of cheese varieties are produced, many of which are unique to a particular region in the world. Cheese comes in soft, hard, semi-hard, hard ripened, and unripened varieties. The various characteristics of cheese are due to differences in the compositions and types of milk, processes used, and microorganisms

used.

Butter and Ghee: Butter and ghee are examples of fatty milk products. Butter is made by churning milk or cream; in many developing countries, sour whole milk is used to make traditional butter. Ghee is made by extracting the water from butter and is particularly popular in South Asia.

Condensed milk: Condensed milk is made by removing water and concentrating the milk solids in whole or skimmed milk. Sweetened or unsweetened condensed milk is available, but most is sweetened. Condensed milk, for example, is frequently substituted for jam in cooking and baking in Latin America.

Evaporated milk: Evaporated milks are made by removing the water from whole or skimmed milk. Heat treatment is used to make milk bacteriologically safe and stable.

Cream: It’s the portion of milk that contains the most milk fat;                it is obtained by skimming or centrifuging the milk.

Whey products: Whey is defined as "the liquid part of the milk that remains after the separation of curd". It is primarily used in the production of whey cheese, whey drinks, and fermented whey drinks. The main industrial applications are in the production of lactose, whey paste, and dried whey. Whey can be sweet (from rennet-coagulated cheese production) or acidic (from the production of acid-coagulated cheeses).

Casein: Casein is the primary protein found in milk and is used as an ingredient in a variety of products such as cheese, bakery goods, paints, and glues. It is extracted from skimmed milk using rennet or harmless lactic acid-producing bacteria.

Milk and Milk products adulteration and its harmful impact on health

One of the most serious issues in India is milk adulteration. According to FSSAI, "Adulterant means any material which is or could be employed for making the food unsafe or sub-standard or misbranded or containing extraneous matter. The following is a list of the nine most common adulterants found in milk and milk products.

Water: The most common adulterant in milk is water. To increase the volume of milk, it is usually diluted with water. It decreases nutritional value. Milk tainted with contaminated water may pose serious health risks.

Urea: Urea is used to increase the SNF (solid-not-fat) content of milk. It also contributes to the whiteness of milk. Urea can have a negative impact on kidney function.

Sucrose: Sucrose is commonly added to milk to increase its density.

Starch: Another common adulterant found in milk is starch. To increase the density of milk, starch is added. This helps to keep extraneous water from being detected in milk. Starch consumption can cause diarrhoea in humans.

Glucose : Glucose is added to raise the lactometer reading. It also adds flavour. Diabetic patients are harmed by low-quality glucose.

Hydrogen Peroxide: This substance is added to milk to improve its quality. It keeps milk fresher for longer. Hydrogen Peroxide has a negative impact on the gastrointestinal tract. It can result in gastritis and inflammation.

Maltodextrin: Maltodextrin is a common milk additive. It boosts the production of milk and milk products. Milk tainted with maltodextrin may cause allergies and diarrhoea.

Salt: Sodium Chloride, also known as salt, is added to milk to increase its density and prevent the detection of added water. People with high blood pressure should avoid drinking milk that has been tainted with salt.

Neutralizers: Neutralizers such as alkali bicarbonates and carbonates are added to milk to neutralise the acidity that has developed. Neutralizers are harmful to human health. It causes gastrointestinal problems. ⁽⁵⁾

Recent Recall of milk and milk products

Lyons Magnus, a food and beverage manufacturer, initially issued a voluntary recall involving 53 products on July 28, 2022. According to an announcement on the Food and Drug Administration website, the Fresno, California-based company expanded the recall last week, increasing the list to more than 80 products across nearly two dozen brands, including Organic Valley, Oatly, and Ensure.

Reason for recall: The FDA's main concern was Cronobacter sakazakii contamination, which can cause common symptoms like fever, vomiting, and urinary tract infections. Cronobacter sakazakii can cause meningitis and bloodstream infections in severe cases. According to the US Centers for Disease Control and Prevention, children, seniors over the age of 65, and people with weakened immune systems are especially vulnerable to illness caused by this contamination.^(6,7)

Some of recall milk products are listed in below

Standards For Milk and Milk Products Set by FSSAI ⁽⁸⁾

In view of the risk factors associated with milk and dairy products testing, certain guidelines and regulations have been established regionally and internationally.

• Food Safety and Standards (Food Products Standards and Food Additives) Regulations
• Prevention of Food Adulteration Act (PFA)
• Milk and Milk Products Order (MMPO)
• Bureau of Indian Standards (BIS)
• Agricultural Produce (Grading and Marking) Act (AGMARK)
• Food and Drug Administration (FDA)
• British Retail Consortium (BRC)
• Food Safety System Certification (FSSC 2200)
• International Featured Standards (IFS)
• Global Food Safety Initiative (GFSI)

The Food Safety and Standards Authority of India (FSSAI) published its notification on revised milk and milk product standards in the Indian Gazette. The revised standards are scheduled to go into effect on July 1, 2020.

For milk and milk products in India, the following are some different categories and FSSAI standards:

Specific Identified Milk: For the species of cow, buffalo, sheep, camel, and goat, there are different milk standards for SNF and fat. Pasteurization, sterilisation, boiling, or ultra-high temperature treatment are all options for treating this milk.

Mixed Milk: This milk is defined as a combination of milk created by mixing milk from various species, as described above. The required percentages of SNF and fat for combined milk are 4.5% and 8.5%, respectively.

Toned Milk, Full Cream, Standardized Milk, Skimmed Milk, and Double Toned Milk: These types of milk are covered by the FSSAI standards for milk and milk products, and they are created by mixing the milk of various animals, including cow, buffalo, sheep, and coat, among others.

Recommendation Milk: This milk combines milk fat and SNF in preserved forms with or without drinkable water to create milk products that meet the requirements of the FASSI Standards for milk and milk products.

Reconstituted Milk or Milk Products: milk produced by mixing concentrated or dried milk & milk products with potable (drinking) water. It is the quantity needed to restore the ideal water to solids ratio so that similar finished milk products can be produced.

Quality and Testing

A high-quality raw milk must be clear of debris and sediment, free of off flavours, normal in composition and acidity, low in bacteria, and devoid of chemicals (such as antibiotics and detergents). The main element affecting the quality of milk products is the quality of the raw milk. Only high-quality raw milk can be used to make products made from milk.

Milk testing and quality control should occur at all stages of the dairy supply chain. Milk can be tested for the following contaminants:

Quantity: measured in terms of volume or weight;

Organoleptic characteristics include appearance, taste, and smell, as well as compositional characteristics such as fat, solid, and protein content.

Physicochemical characteristics;

Hygienic characteristics include hygienic conditions, cleanliness, and quality; adulteration - with water, preservatives, added solids, and so on; and drug residues.

Taste, smell, and visual observation are milk testing methods suitable for small-scale dairy producers and processors in developing countries (organoleptic tests)

A density metre or a lactometer is used to determine the specific density of milk.

Clot-on-boiling testing is used to determine whether milk is sour or abnormal.

Acidity testing to determine the amount of lactic acid in milk

The Gerber test is used to determine the amount of fat in milk.

Eurofins advantages

Eurofins' comprehensive portfolio includes not only innovative DNA-based milk authentication methods, but also all parameters to ensure the overall quality and safety of milk and dairy products. Eurofins Food Testing is set up with a team of highly dedicated and skilled individuals to provide world class laboratory testing with the best service.

References

1. https://www.hsph.harvard.edu/nutritionsource/milk/
2. https://www.usdairy.com/dairy-nutrition/products
3. https://commons.wikimedia.org/wiki/File:Composition_of_Milk_
4. https://www.fao.org/dairy-production-products/products/types-and-characteristics/en/
5. http://www.delmosresearch.com/2020/07/12/9-common-adulterants-found-in-milk-and-milk-products/
6. https://economictimes.indiatimes.com/news/international/us/us-fda-recalls-lyon-magnuss-oatly-oat-milk-52-other-items-heres-why/articleshow/93293987.cms
7. https://www.usatoday.com/story/money/food/2022/08/18/ensure-oatly-organic-valley-recall-bacteria-contamination-risk/10357037002/
8. https://corpbiz.io/learning/fssai-standards-for-milk-and-milk-products/

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