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Smartphone app could alert you to cancer-causing chemicals in meat

A new smartphone app could alert users to cancer-causing chemicals in processed meats such as sausage, ham, bacon and salami.

Scientists in Spain have developed a system with a color-changing film called ‘POLYSEN’ that consumers can stick to meat products.

The labels darken when they detect high levels of nitrite — a meat preservative that can potentially form cancer-causing compounds.

Users can then take a picture of the film with a smartphone and a specially developed app analyzes the color and gives a nitrite concentration value.

Salted and processed meats, such as salami and bacon, are often treated with nitrite or nitrate salts to make them look and taste fresh (file photo)

The image from the researchers' paper shows that the system works.  Discs punched from the film are placed on meat samples for 15 minutes to react with nitrite.  The discs are then removed and dipped in sodium hydroxide solution for one minute to develop the color.  The higher the nitrite present, the deeper the yellowish tint of the film.  A smartphone app calibrates itself when a table of reference disks is photographed in the same image

The image from the researchers’ paper shows that the system works. Discs punched from the film are placed on meat samples for 15 minutes to react with nitrite. The discs are then removed and dipped in sodium hydroxide solution for one minute to develop the color. The higher the nitrite present, the deeper the yellowish tint of the film. A smartphone app calibrates itself when a table of reference disks is photographed in the same image

HOW DOES ‘POLYSEN’ WORK?

POLYSEN, or ‘polymeric sensor’, is a film made of four monomers and hydrochloric acid.

Discs punched from the film are placed on meat samples for 15 minutes to react with nitrite.

The discs are then removed and dipped in sodium hydroxide solution for one minute to develop the color.

The higher the nitrite present, the deeper the yellowish tint of the film.

A smartphone app calibrates itself when a table of reference disks is photographed in the same image.

The system was developed by experts from the Universidad de Burgos in Spain and detailed in a new study, published in ACS applied materials and interfaces.

“There is a need for detection and control of various chemical compounds that are added to processed foods, such as processed meat,” they say.

‘Our method is a major step forward in terms of analysis time, simplicity and orientation for use by the average citizen.’

Cured and processed meats, such as bacon, hot dogs, ham and sausage (including Mortadella, an Italian luncheon meat), are often treated with nitrite or nitrate to make them look and taste fresh.

Nitrites are widely used in processed meats to extend shelf life by repelling bacteria that can cause diseases such as salmonella, listeriosis and botulism.

Crucially, they also add a tantalizing tangy flavor and a pink hue to products like bacon, making them look tastier.

Although nitrate is relatively stable, it can be converted in the body to the more reactive nitrite ion.

In the acidic environment of the stomach or under the high heat of a frying pan, nitrite can react to form nitrosamines, which have been linked to the development of several cancers.

For this reason, consumers want to limit the consumption of these preservatives, but it has been difficult to determine how much is in a food.

Nitrites add a tantalizing spicy flavor and a shopper-seductive fresh pink hue to products like sausage, ham, bacon and salami (file photo)

Nitrites add a tantalizing spicy flavor and a shopper-seductive fresh pink hue to products like sausage, ham, bacon and salami (file photo)

Here a worker packs slices of Mortadella, an Italian luncheon meat, in a factory (file photo)

Here a worker packs slices of Mortadella, an Italian luncheon meat, in a factory (file photo)

So the researchers crated the new POLYSEN film — short for “polymeric sensor” — which is made from four monomers and hydrochloric acid.

To create a ‘reference map’, first die-cut discs were placed on five different meat samples for 15 minutes, allowing the monomer units and acid in the film to react with nitrite.

The meat samples all had different nitrite concentrations, so the researchers knew the slices would vary in color.

The discs were then removed and dipped in sodium hydroxide solution for one minute to develop the color.

The higher the nitrite content in the meat, the deeper the yellowish tint of each film became.

To calibrate the system, die cut discs were placed on five different meat samples for 15 minutes, allowing the monomer units and acid in the film to react with nitrite.

To calibrate the system, die cut discs were placed on five different meat samples for 15 minutes, allowing the monomer units and acid in the film to react with nitrite.

Next, the researchers created the smartphone app that uses colorimetry — which uses light to determine the concentration of certain compounds.

When photographed in the same image as the reference map, the app can return a nitrite estimate for the sample disk.

The team tested the film on meat they prepared and treated with nitrite, in addition to store-bought meat.

They found that the POLYSEN-based method produced results comparable to those obtained with a traditional and more complex nitrite detection method.

In addition, POLYSEN complied with European regulations for the migration of substances from the film to the food.

While the team has only demonstrated the system for now, it could provide consumers with an easy-to-use and inexpensive way to determine nitrite levels in foods in the future.

‘This study is intended as a proof of concept demonstrating that the methodology is practical and works’, they conclude.

NITRITES AND NITRATES: A PRIMER

Nitrite and nitrate are often used for drying meat and other perishable products.

They are also added to meat to keep it red and give it flavor.

Nitrate also occurs naturally in vegetables, with the highest concentrations in leafy greens such as spinach and lettuce.

It can also enter the food chain as an environmental pollutant in water, due to its use in intensive farming practices, animal husbandry and sewage drainage.

Nitrite in food (and nitrate that is converted to nitrite in the body) can contribute to the formation of a group of compounds known as nitrosamines, some of which are carcinogenic, ie can cause cancer.

In 2015, the World Health Organization warned that the risk of colon cancer is significantly increased by eating processed meats such as bacon that have traditionally had nitrites added while they are being cured.

The current acceptable daily intake for nitrates is 3.7 milligrams per kilogram of body weight per day, according to the European Food Safety Authority (EFSA).

The EFSA’s acceptable daily intake of nitrites is 0.07 mg per kilogram of weight per day.

Source: EFSA

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