Sell-by. Best-before. Use-by.
Those ever-prevalent labels on perishable packaged foods are often used as a barometer to determine when to throw out the food product. As it turns out, these labels are only advisory and just define the last date recommended for the use of the product while at peak quality.
However, approximately 60% of household food waste arises from products "not used in time," according to UK's Waste and Resources Action Program ( WRAP).
The sell-by date is a cautious estimate at best, but other than the standby nose test, how can one know if the food is still safe to eat or not? Well, university researchers in Europe hope a new plastic sensor, together with packaging, can help to solve this issue.
Researchers at Eindhoven University of Technology, Universitá di Catania, CEA-Liten and STMicroelectronics have invented a plastic analog-digital converter to fight food waste. The researchers say that producers could include an electronic sensor circuit on their packaging and using a scanner or a mobile phone can monitor the acidity level of the food, show the freshness of a steak or whether frozen food was defrosted.
Researcher Eugenio Cantatore with the Eindhoven University of Technology told PlasticsToday there is already a widespread research effort on monitoring food quality using advanced silicon-based sensors, but the problem is that this kind of technology can be costly when applied to each food item.
"If each packaged item must be controlled so that the end user can check the results, a much cheaper solution is needed," he said. "We, together with our partners, make electronics on the same plastic foils that are used already for packaging because we use very low temperature processes. Moreover, we use mostly printing techniques, which are fast and do not waste material. All this holds the promise for cheaper solution than conventional silicon-based electronics."
The plastic semiconductor can even be printed on all kinds of flexible surfaces, which Cantatore says makes it cheaper to use.
The researchers have succeeded in making two different plastic ADCs. Each converts analog signals, such as the output value measured by a sensor, into digital form. One of these new devices is the very first printed ADC ever made.
A sensor circuit consists of four components: the sensor, an amplifier, an ADC to digitize the signal and a radio transmitter that sends the signal to a base station. The plastic ADC was the missing link; the other three components already exist, Cantatore said.
Now researchers are working on the integration of the full electronic chain and Cantatore estimates it will take at least five years before we can see this device on supermarket shelves.
He said this technology had spurred interest in the semiconductor arena and they hope to receive interest from the food and distribution industry.
"Expiration based on direct measurements using sensor in packaging could be much more accurate in ensuring food safety and at the same time less waste," he said.
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