A new smartphone app could alert users to cancer-causing chemicals found in processed meats like sausages, ham, bacon and salami.
Scientists in Spain have created a system that includes a color-changing film called “POLYSEN” that consumers can stick on meat products.
Labels turn darker when they detect high levels of nitrite – a meat preservative that can form potentially carcinogenic compounds.
Users can then take a photo of the film with a smartphone, and a specially developed app will analyze the color and give a nitrite concentration value.
Cured 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 graph in the researchers’ paper shows that the system is working. Discs cut from the film are placed on meat samples for 15 minutes to allow them to react with the nitrite. The disks are then removed and immersed in a solution of sodium hydroxide for one minute to develop the color. The higher the nitrite, the deeper the yellowish tint of the film. A smartphone app self-calibrates when a reference disk array is photographed in the same image
HOW DOES ‘POLYSEN’ WORK?
POLYSEN, or “polymer sensor”, is a film composed of four monomers and hydrochloric acid.
Discs cut from the film are placed on meat samples for 15 minutes to allow them to react with the nitrite.
The disks are then removed and immersed in a solution of sodium hydroxide for one minute to develop the color.
The higher the nitrite, the deeper the yellowish tint of the film.
A smartphone app self-calibrates when a reference disk array is photographed in the same frame.
The system was created by experts from the University of Burgos in Spain and detailed in a new study, published in Applied materials and ACS interfaces.
“There is a need to detect and control different chemical compounds added to processed foods, such as processed meat,” they state.
“Our method represents a big step forward in terms of analysis time, simplicity and orientation for the average citizen to use.”
Cured and processed meats, such as bacon, hot dogs, ham, and sausages (including bologna, an Italian lunch meat), are often treated with nitrite or nitrate to give them their appearance and flavor. fresh taste.
Nitrites are widely used in processed meats to extend their shelf life, by warding off bacteria that can cause illnesses like salmonella, listeriosis and botulism.
Importantly, they also add an enticing tart taste and pink hue to products like bacon, making them more appetizing.
Although nitrate is relatively stable, it can be converted into the more reactive nitrite ion in the body.
When in the acidic environment of the stomach or under the high heat of a frying pan, nitrite can undergo a reaction to form nitrosamines, which have been linked to the development of various cancers.
For this reason, consumers want to limit the consumption of these preservatives, but it is difficult to determine the amount contained in a food.
Nitrites add an alluring tart taste and an alluring cool pink hue to products like sausages, ham, bacon and salami (file photo)
Here, a worker packs slices of mortadella, an Italian meatloaf, in a factory (file photo)
The researchers therefore created the new film POLYSEN – short for “polymeric sensor” – composed of four monomers and hydrochloric acid.
First, to create a “reference chart”, discs cut from the film were placed on five different meat samples for 15 minutes, allowing the monomer units and acid in the film to react with the nitrite.
The meat samples all had different nitrite concentrations, so the researchers knew the discs would vary in color.
The discs were then removed and immersed in a sodium hydroxide solution for one minute to develop the color.
The higher the nitrite present in the meat, the deeper the yellowish tint of each film became.
To calibrate the system, discs cut from the film were placed on five different meat samples for 15 minutes, allowing the monomer units and acid in the film to react with the nitrite.
Next, the researchers created the smartphone app that uses colorimetry – which uses light to determine the concentration of particular compounds.
When photographed in the same frame as the reference graph, the app can return a nitrite estimate for the sample disk.
The team tested the film on prepared and nitrite-treated meats, in addition to store-bought meats.
They found that the POLYSEN-based method produced results similar to those obtained with a traditional, more complex nitrite detection method.
In addition, POLYSEN has complied with European regulations on the migration of substances from the film to food.
Although the team has only demonstrated the system for now, it could provide consumers with a user-friendly and inexpensive way to determine nitrite levels in foods in the future.
“This study is intended as a proof of concept in which it has been demonstrated that the methodology is practical and works,” they conclude.
NITRITES AND NITRATES: FIRST
Nitrite and nitrate are commonly used for curing meat and other perishable products.
They are also added to meat to keep it red and give it flavor.
Nitrate is also found naturally in vegetables, with the highest concentrations found in leafy vegetables like spinach and lettuce.
It can also enter the food chain as an environmental pollutant in water, due to its use in intensive farming methods, animal production and wastewater discharges.
Nitrite in food (and nitrate converted to nitrite in the body) can contribute to the formation of a group of compounds called nitrosamines, some of which are carcinogenic, that is, they have the potential to cause cancer.
In 2015, the World Health Organization warned that there was a significant increase in the risk of bowel cancer linked to the consumption of processed meats such as bacon, which traditionally contain nitrites added as you go. measurement of their drying.
The current acceptable daily intake for nitrates, according to the European Food Safety Authority (EFSA), is 3.7 milligrams per kilogram of body weight per day.
The EFSA Acceptable Daily Intake for nitrites is 0.07 mg per kilogram of weight each day.