You point your phone at the contents of your fridge, and it tells you which groceries are fresh, which are on the cusp of spoiling, and which are best left untouched. This isn’t a far-fetched scenario, but a reality thanks to a new tech discovery made by a group of researchers, who have presented their findings in the journal, Nature Food.
Food spoilage is a huge driver of food waste, and also accelerates the spread of disease through microbes that cause food to rot. This spoilage is perhaps most worrying when it comes to meat, because it harbors diseases that pose more risk to human health. Wasted meat also represents a much larger footprint of emissions, land, and water use associated with its high-impact production on farms.
In total, 240 million tons of meat including chicken, fish and beef are binned each year, and the researchers on the new study wanted to find a way to stop that loss at the level of grocery stores and in homes where much of it occurs. While there are many food sensors under development, most are costly and cumbersome, and can only be used in a lab: the researchers wanted something portable, easy to use and cheap to make.
After some trial and error, their solution took shape in a polymer patch about the size of a postage stamp, which can be pasted inside food packaging, where it’s able to detect changes in meat freshness. It accomplishes this with a highly-sensitive chemical structure, which changes in response to the presence of biogenic amines, which are compounds that protein-rich products emit as they start to degrade.
As this happens, the changes to the polymer’s structure are converted into an electrical signal in a sensor that’s laminated onto the polymer patch. The next stage involves a phone equipped with a common technology called near-field communication—which enables an exchange of information between two electronic devices. “Once a near-field communication-compatible mobile phone is placed close to the sensor, the chip receives power,” the researchers explain in their study. This allows it to relay the data about food compounds through an inbuilt wireless antennae, back to the phone, “thus enabling quick identification of food status.”
To test how well this system works in reality, the researchers set up an experiment where pieces of chicken and beef were monitored by the patch sensors at different temperatures, ranging from below freezing, to 4 °C, and then 20 °C. This revealed that the polymer patches were sensitive enough to detect signs of rotting—including compounds like the aptly-named putrescine and cadaverine—at levels much lower than those at which they become toxic.
What’s more, for the samples that had been kept at 20 °C the sensors detected an intensifying signal as the days passed and meat decayed. This proved the tool’s ability to not only detect when a food has gone off, but ideally also to identify a threshold below which food is safe, and beyond which it’s no longer edible.
With this information the researchers have developed a user-friendly mobile app that “is programmed to give a ‘Risky’ error” above a certain threshold measurement, they write. This kind of detail could pave the path for a more refined future app that could suggest to consumers when the prime time is to eat their groceries, before they hit that risky peak.
Currently, this tech can be produced at scale for less than $1, and there’s potential to develop it for use on a variety of other foods to save them from the bin as well. The researchers also suggest that biodegradable alternatives to the polymer patch could be investigated to avoid the additional production of plastic packaging.
Those are challenges for future research. For now, the discovery puts a technological solution to a massive global problem, right into the palm of our hands.
Istif et. al. “Miniaturized wireless sensor enables real-time monitoring of food spoilage.” Nature Food. 2023.
Image: ©Anthropocene Magazine
