Current strategies for measuring freshness can be highly sensitive to spoilage but require bulky, slow equipment, which prevents real-time analysis. Some newer methods designed to speed up the testing process have fallen short in sensitivity.
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 vapor 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.
Story source;American Chemical Society.