How food freshness sensors could impact supply chains

How food freshness sensors could impact supply chains

August 24, 2023

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What do the various dates for “best if used by,” “sell by,” expiration, freshness or other labels on food packaging mean? Not much actually. Eventually there could be a new system entirely.

This confusion and concerns around wasted food have motivated a crowd of major companies, researchers and startups to address the problem of food freshness. By using various sensor technologies, a product’s status can be known along the supply chain all the way to grocery shoppers, who hopefully won’t throw out food that’s safe to eat after they get it home. 

As per the U.S. Department of Agriculture, “[t]here are no uniform or universally accepted descriptions used on food labels for open dating in the United States.” Confusion around this issue likely contributes to the 38% of unused food — 80 million tons — in the U.S. each year, according to nonprofit ReFEDThe Food Date Labeling Act was recently reintroduced in Congress in an attempt to address this issue, and states have also considered policy changes. 

“The current standards are the ‘use by’ date that has to do with whatever the manufacturer decides to put there,” said Silvana Andreescu, professor of bioanalytical chemistry and head of the biosensors lab at Clarkson University. “It doesn’t take into account storage conditions and transportation conditions, so it is not related necessarily with the quality and the value of the food at the time of use.”

Best for what?

The condition of the majority of food products as they travel along supply chains is unknown because there’s no quality monitoring, apart from perhaps a visual inspection at the grocery store, said J.-C. Chiao, professor in the electrical and computer engineering department at Southern Methodist University. “You don’t know what happened to the product,” he said.

There are a variety of approaches being developed and marketed using inks, pH sensors, hydrogels and other technologies. Andreescu and Chiao have both been involved in projects to create freshness sensors.

Andreescu’s group developed a sensor that changes color when the food begins to degrade. Fish and meat both produce more hypoxanthine as they begin to spoil. The biosensors in their paper label react to that increase and trigger a color change. The label itself is placed inside packaging on a membrane so it’s not in direct contact with the food. 

Chiao supervised SMU doctoral student Khengdauliu Chawang, who developed a low-cost pH sensor that detects the level of hydrogen ions in the food product. The ions affect the pH levels and that info is relayed to servers along the supply chain using radiofrequency identification, or RFID, technology. It’s designed to be easily mass produced and, at 2 millimeters by 10 millimeters, is very small.

Chawang, who is from the Nagaland region in northeastern India, was motivated to address freshness for personal reasons. “Food waste is such a problem in the community that I come from,” she said. “There are consequences for that.”

Another product that uses color coding is the Freshtag from Swedish and U.S.-based research and development company Vitsab. The Freshtag is a freshness indicator that changes like a stoplight from green to red, using food-safe adhesive to attach to a label. It’s calibrated to specific food product temperature regulations, explained President Jeff Desrosiers. The company is also working on an ink-based technology that would be embedded in a package’s barcode. The barcode would fade according to the temperature profile and then be unsellable when it was past edibility. 

“If something is well handled, it’s good well beyond that [‘use by’ or expiration] date,” Desrosiers said. “But if it’s abused, it’s not even good until that date. So the industry has to come up with something.”

This field has also seen engagement from companies around the world. For example, Sweden’s Innoscentia offers a label that attaches to plastic film of a meat package. When the meat degrades, it releases volatile organic compounds which react with the label’s ink, causing it to change color. 

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