INSIDE EDITION Investigates Food at Gas Station Mini-Marts

If you're buying anything at a gas station's mini mart, you might want to check the expiration date. Inside Edition's I-Squad investigates gas station mini marts.

Pulling up to the pump isn't just for a fill-up anymore. It's a chance to do some last minute shopping. Milk, juice, eggs, all kinds of groceries are available at gas marts around the country.

You usually pay a little extra at these mini-marts, but the price isn't the only number you should be checking out. The expiration dates may surprise you.

We decided to do some shopping. INSIDE EDITION's Lisa Guerrero found mayonnaise with a January 2010 expiration date, and baby food that expired in September.

You may not want to bake a cake with the flour we bought at a gas mart in New Jersey. It expired in July of 2009. And even Popeye wouldn't eat the spinach we found.

Reading the expiration date, Guerrero says, "May of 2008. You heard right. That spinach was two-and-a-half years out of date."

We found out-of-date items at almost every gas station mini-mart we visited.

"I'm shocked that these things are left on the shelves," said nutrition expert Felicia Stoler. "As a mother and as a health care professional, I wouldn't want to serve expired food to my friends or family."

But what would happen if we returned some of the out-of-date items. Would they be discarded, or put right back on the shelf?

First, we used invisible ink to mark them with I. E. for INSIDE EDITION. It only shows up with a special blue light.

We returned a Heinz cocktail sauce, which was a year-and-five-months out-of-date, to a gas mart in New Jersey.

We got our money back, but when we went back the next day, you guessed it, the jar had been put back on the shelf. Sure enough, the I.E. marking was visible under the blue light.

So we returned to talk to the owner.

Guerrero said, "Hi, I'm Lisa Guerero with INSIDE EDITION.

He offered this explanation, saying, "The night shift saw it on the side and didn't know it was on the side because it was past due, and put it back on the shelf by mistake. I'm sorry about that. I will talk to the manager."

At another store, the manager had no clue she was selling products that had expired more than 2 years ago, like the spinach and headache medication.

Guerrero said to the manager, "So you have no explanation that this has been on your shelf for two years?"

"No, it's not supposed to be," said the manager.

"It's not supposed to be," said Guerrero.

So what can you do? Felicia Stoler says be vigilent. Check all grocery expiration dates, especially in smaller stores like mini-marts.

"We wouldn't accept going into a restaurant and eating bad food and getting sick. So why should we accept going into a convenience store and buying food that's potentially old and spoiled?" said Stoler.