Around £12.5 billion-worth of food is wasted every year. Image Credit: Africa Studio/Shutterstock.com
The continuous increase in the world’s population and rapid urbanization have already taken a toll on annual food production. The two main causes of food wastage are spoilage and exceeding the use-by date. This article emphasizes how scientists have designed sensors to prevent food wastage.
Food wastage has become a global issue. Food waste also has an environmental impact in terms of carbon emission and plastic pollution (common food packaging material). A recent survey has evaluated that one in three consumers in the United Kingdom discards food because it reaches the use-by date. However, these foods remain perfectly safe for consumption and, sadly, because of the lack of a proper indicator, a loss of £12.5 billion-worth of food is incurred every year.
Ethylene Sensors to Monitor Fruits and Vegetables During Shipment and Storage
Ethylene is a colorless and sweet-smelling (gas) plant hormone that stimulates plant growth, ripening of fruit and blooming of flowers. This could be correlated with an increase in the concentration of ethylene hormone. Overproduction of ethylene also occurs when the plant undergoes stress conditions causing premature ripening and wilting. The U.S. Department of Agriculture estimated that every year U.S. supermarkets lose around 12% of their vegetables and fruits due to spoilage.
Timothy Swager, the John D. MacArthur Professor of Chemistry at MIT, and his research team have designed a small sensor for the detection of ethylene gas at a very low concentration (15 parts per billion), which in turn could help to prevent food spoilage.
They envisioned that the sensor could help during the transportation of fruits and vegetables, from storage to the supermarkets. The sensors measure the exact level of ethylene gas so that necessary precautionary measures can be taken to minimize wastage of food in transit. This sensor is made up of carbon nanotubes with semiconductive properties.
How can edible food sensors help us?
The ethylene sensor, developed in 2012 by Swager’s research team, had some limitations. It could detect the concentration of ethylene to 500 parts per billion only. As the sensors also contain copper atoms, they get corroded easily in the presence of oxygen and eventually stop working.
The new ethylene sensor, developed in 2020, is also based on carbon nanotubes but with a different working principle, i.e., Wacker oxidation. In this sensor, the scientists used palladium catalyst instead of copper. During oxidation, the palladium catalyst gains electrons and makes the carbon nanotube more conductive by passing on the extra electrons. The concentration of ethylene is evaluated by measuring the change of current flow in carbon nanotubes. The sensor becomes active immediately when exposed to ethylene gas and comes back to the ground state in its absence. The patent has been filed for this new sensor by the MIT research team.
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Low-Cost, Smartphone-Linked Spoilage Sensors for Supermarkets and Consumers
A low-cost, eco-friendly, rapid, and smartphone-linked spoilage sensor for fish and meat packaging has been developed by Dr. Firat Güder's team at the Department of Bioengineering, Imperial College London. They claim that the new sensors could help reduce food waste for supermarkets and consumers.
This sensor is based on paper-based electrical gas sensors (PEGS), and can detect gases (ammonia and trimethylamine), which indicate spoilage in meat and fish products. Since smartphones could read the sensor data, the consumers can hold their phone up to the packaging and determine whether the food is safe for consumption.
Güder's team has developed the sensor by printing carbon electrodes onto readily available cellulose paper. These sensors are linked with ‘near field communication (NFC)’ tags, i.e., a series of microchips that can be read by nearby mobile devices.
The scientists reported that when the sensor was tested for its efficiency to detect spoiled fish and meat in packages under laboratory conditions, PEGS rapidly revealed its high-sensitivity and accuracy towards the detection of spoilage gases at trace amounts. This sensor is regarded as safe as the materials used for its production are biodegradable and non-toxic.
Find out more about the different types of sensors available on the market today.
Misleading Use-By Dates on Food Packaging and how Sensors could Help
Use-by dates that appear on packaged food are often misleading.
Researchers believe that the sensor could gradually replace the ‘use-by’ date, which is not a reliable indicator of edibility and freshness of food products. Consumers often fall sick from foodborne diseases as they solely rely on the use-by dates or “sniff-test”.
However, food often gets spoiled due to poor storage conditions before its mentioned date. On the other hand, people tend to throw away perfectly safe food just by misjudging its freshness from the indicated use-by date. The main aim of Güder's team is to provide a reliable and user-friendly sensor that could give objective feedback to consumers on foods’ freshness and safety for consumption. This could reduce not only unnecessary food wastage but also decrease subsequent plastic pollution.
As the commercially available food spoilage sensors are too expensive or too difficult to be interpreted by a layman, they are not commonly used by consumers. Scientists hope that simple, low-cost sensors could be economically helpful for both consumers and supermarkets.
References and Further Reading
Trafton, A. (2020) New sensor could help prevent food waste. [Online] MIT News. Available at: http://news.mit.edu/2020/ethylene-sensor-food-waste-0318 (Accessed on 10 July 2020).
Brogen, C. (2019) Food freshness sensors could replace ‘use-by’ dates to cut food waste. [Online] Imperial College London. Available at: https://www.imperial.ac.uk/news/191413/food-freshness-sensors-could-replace-use-by/ (Accessed on 10 July 2020).
Barandun,G., et al. (2013) Cellulose fibers enable near zero-cost electrical sensing of water-soluble gases. ACS Sensors, 4, 6, 1662–1669. https://pubs.acs.org/doi/10.1021/acssensors.9b0055