Taking Adulteration Analysis to the Next Level

After the 2008 melamine scandal in China, detecting adulteration in milk has also become a critical application for IR analysis. Typically, milk with a higher protein content will in turn attract a higher price in the market. Unfortunately, the typical methods for testing the protein content of a milk product are based around measuring nitrogen levels. This led to the nitrogen-rich, but highly toxic compound melamine being added to milk products in order to raise their apparent protein content. IR analysis is crucial in determining the concentration of this adulterant in milk, as well as identifying any other adulterants such as sugars or urea.

Next Level: LC-MS/MS and ICP-MS

In instances of food fraud where adulterants are at too low a concentration to be picked up by IR, or where stricter regulations demand more precise determination of adulterant levels, LC-MS/MS comes into play.

In the case of milk, for example, mass spectrometry offers an alternative method for the detection of adulterants. Aside from melamine and the addition of other small molecules, large molecules can also be added to milk for the purpose of fraud—for example, diluting more expensive milks such as buffalo, camel, goat, or sheep, with cow’s milk. By using LC-MS/MS, it is possible to measure the addition of bovine milk to these pricier milks by detecting the presence of β-lactoglobulin A. (See Figure 1.) This species-specific marker protein is found only in cow’s milk, enabling users to detect the presence of this cheaper alternative in other more expensive types of milk.

A similar method can be used to detect the presence of pork in certain foods, which is crucial for consumers whose culture or religion prohibits the consumption of this meat. Pork meat, like milk, contains certain peptides that can be used as biomarkers for detection in food samples. LC-MS/MS enables the detection of these biomarkers, offering a rapid, selective, and sensitive method for analyzing raw, cooked, and processed meat products for the presence of pork.

LC-MS/MS is also crucial for the detection of synthetic azo and non-azo dyes down to 10-100 ppb concentrations. Although once used in the industry as food colorings, these dyes have now been widely banned due to their potentially genotoxic or carcinogenic properties. However, they are still being detected in the food supply chain—particularly in spices—making it crucial that sensitive methods are available for the detection of even minuscule amounts of these banned substances. First, a simple dye extraction is performed using an organic solvent, with the filtrate then injected into the liquid chromatography column. Using certain methods, LC-MS/MS can achieve exceptional chromatographic repeatability and peak resolution in under four minutes.

Additionally, LC-MS/MS can be used to detect both adulterants and contaminants in wine. As with other food products such as olive oil, additives might be introduced into wine to improve its flavor or color. There is also a high chance pesticides or fungicides could end up in the final product if the grapevines have been sprayed with these compounds during growth. Both of these additives, whether intentional or unintentional, can cause significant harm to humans if ingested. It is therefore imperative that they are detected as quickly and reliably as possible. LC-MS/MS can simultaneously determine the concentrations of both pesticides and pigments in a single analytical run, providing users with a quick and easy method for monitoring these compounds in their products.

ICP-MS can also be used to combat fraud in wine by helping to determine the geographical origin of grapes—an important factor in driving product price and consumer expectations.

Using ICP-MS, it is possible to identify the unique and varying levels of trace elements present in the wine. After an elemental profile is created by ICP-MS, informatics solutions can then deliver a visualization of the data correlating the levels of trace elements in certain wines to that in different, geographically situated soils. (See Figure 2.)

Future of Combating Food Fraud

Although food fraud is certainly not a new concept, the increasing cost of food ingredients is making it more common. This is combined with ever-stricter regulations and the fact that those committing food fraud are also becoming more creative and intelligent in finding new ways to adulterate food. It’s therefore clear that the more in-depth information available on fraudulent activity, the more effectively fraud can be reduced and controlled.