You are at the grocery store to purchase a package of fresh ground beef, or a bag of green beans, or some fresh salmon. Maybe you can gauge freshness by appearance or you perhaps you rely on the sell-by date. But you cannot smell or touch. So how do you know the product is still fresh and unspoiled? Wouldn’t it be great for consumers (and retailers) to know if a packaged product still retained freshness, even past the shelf-life.
The solution, studied for more than 20 years, are biosensors – devices or strips placed inside or incorporated into packages that provide visible freshness information. Also referred to more recently as smart packages, they now can be as simple as a barcode that you scan with your smart phone and within a second, you get a freshness report.
Still, the key to this technology is a chemical way to assess freshness or spoilage inside a package. Usually, they are based on headspace analysis of specific volatiles produced by spoilage bacteria. The most common spoilage targets include biogenic amines (as described here, here, and here), pH (here and here) and hydrogen sulfide
When that target molecule is produced by spoilage microbes, it reacts with receptors embedded in the package. There could be a color change, or as noted above, the latest generation systems convey the response via a barcode.
These systems are not only provide point of purchase freshness information, they continue to inform consumers after purchase, i.e., when the product is in their refrigerator. Thus, food waste can be minimized.
Image from www.foodnavigator.com