Casey Thompson always keeps snacks in the house for her hungry two year old, Stella.
"Fresh fruit, eggs, milk, strawberries," she said.
But making sure the food is still ok to eat can be difficult. She keeps tabs on expiration dates but if there's any doubt about freshness.
Last week's snack becomes today's garbage. It's estimated the average American family throws out more than $2,000 worth of food every year.
"Milk for instance, my husband will smell it and test it that way. I don't want to smell rotten milk," Thompson said.
But a new tool could make the old smell test a thing of the past. Chinese researcher Choa Zhang flew all the way to a scientific conference in Dallas to show off his new food smart tag. "I would consider myself a germaphobe," Zhang said.
The gel-based temperature-sensitive tags are placed on the packaging and change color over time, mimicking the rate at which food goes from fresh to foul.
A red tag means the food is still fresh. As the food starts to go bad the tag changes color. Green means the food is spoiled.
Zhang is now trying to sell his invention to food makers. He believes it could one day help parents like Thompson from throwing out valuable food that's still good, and avoiding food that's gone bad.
Omar Villafranca - CBS News