New York: Deciding whether to cook or toss a steak that has been in the refrigrator for a few days calls for a sniff test. Scientists have now discovered a method that uses nanotubes to quickly detect spoilage.
It could help make sure meats are safe when they hit store shelves.
Transporting meats and seafood from the farm or sea to the market while they're still fresh is a high priority.
Current strategies for measuring freshness can be highly sensitive to spoilage, which prevents real-time analysis.
To speed up the testing process, researchers Yanke Che and colleagues wanted to develop one simple test that could deliver both rapid and sensitive results.
The researchers turned to highly fluorescent, hollow nanotubes that grow dim when they react with compounds given off by meat as it decomposes.
To test the nanotubes, the team sealed commercial samples -- 1 gram each -- of pork, beef, chicken, fish and shrimp in containers for up to four days.
When they exposed the portable system to a teaspoon of vapour emitted by the samples, it reacted in under an hour, fast enough to serve as a real-time measure of freshness.
The researchers also found that if the tubes' glow dulled by more than 10 percent, this meant a sample was spoiled.
The study was published in the new journal called ACS Sensors.