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Technique exposes 'invisible' milk adulteration

Research simulates fraud with four most used adulterants and analyzes the reactions caused by them

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Milk is recognized as a source of essential nutrients, such as proteins, lipids and quality fats. But, due to advances in technology to meet growing demand, production costs have increased, making the product a target for adulteration. The addition of vegetable fat to increase the fat content or simply water to increase the volume, are adulterations detected by routine methods to certify the quality of milk, such as microbiological tests investigating the concentration of fungi and bacteria or tests on nutritional composition.

However, adulteration techniques have also become more sophisticated, for example, with the addition of formaldehyde (formaldehyde), hydrogen peroxide (hydrogen peroxide), sodium hypochlorite (candida) and sodium hydroxide (caustic soda), which even in Very low quantities, undetectable by conventional methods, extend the shelf life of milk – which brings greater profitability for adulterators. These adulterants were the subject of Tatiane Melina Guerreiro's doctoral thesis, developed at the Faculty of Pharmaceutical Sciences (FCF) at Unicamp, under the guidance of Professor Rodrigo Catharino and with a Fapesp research grant. 

Rodrigo Catharino, who coordinates the Innovare Biomarkers Laboratory, explains that the research simulates the adulteration of milk samples with the four adulterants mentioned, but without the purpose of simply identifying them. “The objective was to analyze the reactions they provoke when interacting with milk, that is, the generation of potentially harmful by-products and the implications for consumer health. In terms of volume, the use of adulterants has been decreasing, in order to increase the life of the product on the shelf – and with this, yield and profit are automatically improved.”

Photo: Scarpa
Professor Rodrigo Catharino, thesis advisor: ranking of the most important markers for the adulterated product

According to the FCF professor, adulterers act without worrying about being caught, as the amount of the substance is so small that it passes invisible through conventional tests. “We then went to a reliable producer of raw milk and carried out adulterations in the laboratory, down to very small quantities, reaching 1% of each substance. And by combining the high-resolution technique of mass spectrometry with a powerful statistical analysis, which we call PLSDA, we were able to compare the components identified in raw milk and adulterated milk. The result was a ranking of the most important molecules (markers) for the adulterated product.”

Catharino states that in the case of formaldehyde, for example, it was found that formaldehyde was linked to milk molecules, even in very low quantities of the substance, which can result in gastrointestinal problems. “We have not done clinical studies, but there is no doubt that this type of adulteration causes harm. To give another example, hydrogen peroxide (hydrogen peroxide) in milk generates a high concentration of oxidized compounds. If the intention is to offer the consumer a food that improves their nutritional profile, with proteins and lipids in an adequate composition, adulterated milk leads to the opposite: a highly oxidized system, which will be harmful to health.”

This aspect, that even in very low quantities, such substances are sufficient to oxidize the matrix, had not been studied before, according to the Unicamp professor. “There is the aggravating factor that milk is not consumed raw, it is used for a multitude of formulations, such as in the pharmaceutical and food industries. Using this oxidation load throughout an industrial chain based on milk results in poor quality products, exposing the population to serious risks.” 


Trojan Horse

Rodrigo Catharino highlights that the results were different for each substance studied, generating varied sets of markers. “We saw that the greatest degradation of milk, both proteins and lipids, occurs with hydrogen peroxide, despite the increase in shelf life. With formaldehyde, the degradation is smaller, but more worrying, because the formaldehyde binds to proteins and lipids and has a cumulative effect: imagine a substance that passes between membranes and will lodge directly in the site of action, such as the liver, to be processed in a cascade through biochemical pathways. Instead of an essential amino acid, a 'Trojan horse' is introduced into the body, which is formaldehyde.”

Catharino believes that this methodology can serve both quality and consumer protection bodies, as well as companies that use milk as a raw material and want to ensure that the product is not adulterated. “The refinement of adulteration is so tenuous that the producer, in fact, does not even know how to adulterate the milk. Adulteration occurs in the middle of the chain – transport, storage, processing, packaging –, before reaching the shelf and the consumer.”

 

 

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