Lurking in the back of your fridge right now is probably a long-forgotten cucumber or a pack of chicken slowly going bad, destined for the trash.
But what if there was a way to automatically monitor food and alert you when it starts to spoil? That’s the promise of a new tool developed by researchers to “smell” out food that is going off and notify you via a smartphone app.
Inspired by human senses — after all, a quick look and sniff can generally tell us whether most food is still good to eat — the system uses sensors to detect specific chemicals released when food breaks down and changes color in response.
The device, say the team, provides a practical solution to a global problem. In the journal Advanced Functional Materials, they wrote, “Overall, this research develops an odor visualization strategy that enables on-site, real-time, and sensitive monitoring of food quality assessment, ultimately reducing food waste and generating significant economic value.”
Waste not, want not
According to the UN, around one third of all food produced for human consumption is lost or wasted, making reducing food waste one of their key Sustainable Development Goals. The World Health Organization also reports that globally, 33 million healthy years of life are lost annually because of foodborne diseases.
A simple, accessible system for monitoring food freshness in homes, as well as in industrial food storage settings, could go a long way to tackling both of these issues.
The new approach is built on an organic framework bonded by hydrogen molecules forming a rigid, organized lattice structure and enhanced with the rare-earth metal, europium. This structure creates a porous material with tiny cavities that allow it to interact selectively with target molecules, such as those released by spoiling food.
The device was designed to molecules known as biogenic amines, nitrogen-containing compounds formed when amino acids — the building blocks of proteins — break down. They’re found in many healthy systems, including in our body as regulators of blood pressure and neurotransmission, but in food, their accumulation tends to signal spoilage or fermentation as the food starts to deteriorate.
The team’s food sensor is embedded in a gel that changes color in response to contact with these molecules, producing a clear visual measure of whether nearby food has started to spoil. “Importantly,” the authors wrote, “it demonstrates outstanding advantages, including high sensitivity, ultrafast responses (<6 s), and practicability of recyclability, which can be combined with smartphones for on-site BAs detection.”
Previous methods of detecting biogenic amines required complex lab setups or could be only used once, creating even more waste. But the gel in this setup is stable under a variety of temperatures and humidities, and can even be re-used.
When a smartphone app is shown a picture of the color change, it analyzes the image to produce a quantitative value of freshness. The promise of a clear, user-friendly measure of freshness provided within seconds is essential if the technology is to move from the lab into people’s homes.
Trialing the system, the research showed detection of five common types of biogenic amines with high precision in under six seconds, accurately identifying when chicken and prawns started to spoil.
A food sensor that provides a practical solution
It is all too easy to forget to eat food in the fridge before it passes its expiration date. In fact, the European Commission estimates that up to 10% of food waste is linked to date marking itself. A system that helps keep track of fresh food would be of great value in terms of both economics and safety.
The scientists behind the device believe this research is the first step towards such a system.
“We know that it will take a lot of safety and health testing to make this truly commercial, but our work provides a pioneering idea for food freshness monitoring, which we believe will have practical applications in the near future,” said Alituniguli Maimaiti from Tongji University, China. “In addition, if the device is to be expanded commercially, it will need to be enhanced with other properties, such as antimicrobial, or dehumidifying, which will be the focus of our next work.”
Maimaiti envisages the next iteration of the food sensor will be modelled on human perception that not only senses food freshness to warn users of potential spoilage, but also proactively prolongs food life by optimizing the surrounding conditions.
The result could help everyone manage their food a little better, and tackle a global challenge at the same time.
Reference: Bing Yan, et al, Dual-Mode Bionic Visual–Olfactory Co-Sensory for On-Site Biogenic Amines Recognition and Food Freshness Prediction, Advanced Functional Materials (2024). DOI: 10.1002/adfm.202412817
Feature image credit: Ella Olsson on Unsplash
