Q: Products are dated with use-by, best-by and sell- by dates, which is fine if it’s not opened. Is there a rule once products are opened?

— A reader in Plymouth, Mich.

A: What's lurking in your pantry or in your refrigerator can be worrisome. How long products last, especially once they are opened, is a question we all face.

But before you begin to think your pantry or refrigerator is breeding bacteria, consider that because a product has reached it’s expired date doesn’t mean it’s no longer good. Tossing out an item,when it could still be good is a waste (more on this later). The obvious test with a lot of products is the smell and look test. If it smells bad and has mold growing, toss it. Never taste food to determine if it’s still good, says the Food Safety and Inspection Service (FSIS).

Product dates, according to the FSIS, part of the U.S. Department of Agriculture (USDA), are not a guide for safe use — except for infant formula and baby food. The dates, rather, are a quality issue. Dates on packaging, which are not regulated by the federal government except for infant formula and baby foods, tell a consumer how long they can store the food and consume it when it is still at its best.

Keep in mind terms such as “sell-by” and “use-by” have different meanings.

 Sell-by: tells the store how long it can display the food for sale. It's best, of course, to buy the food before it reaches the sell-by date. Refrigerate once you buy it, or freeze it for longer storage.

— Use-by: date is the recommended date for using the product for the best quality. It's important to note, that the FSIS, says that with infant formula that date is a food safety. The agency says not to buy or use baby formula after its use-by date.

— Best if used by/before: another indicator of how long the product will be of best quality.

You can find storage information on certain foods at https://www.fsis.usda.gov

In the last few years, many articles have been written about how much food waste is going on. Food is wasted for various reasons, with one being people don’t know how to determine whether it’s still good or not.

The global experts at Whole Foods Market pegged mindful meal prep as one of their top food trends for 2017. And part of being mindful is reducing food waste. Americans waste some 40 percent of all edible food, according to the National Resources Defense Council, a New York City-based environmental watchdog agency.

At www.nrdc.org

And don’t forget about veggies. While some might look wilted or have softened, that’s OK. Use them in quick sautés, stir-fries or soups — see recipe below. You can also save those vegetable scraps, sticking them in a freezer bag. When you gather up enough, make vegetable stock.

Lastly, thanks to this reader from Plymouth for leading me to several web sites that also have useful information. At www.stilltasty.com and www.shelflifeadvice.com

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PASTA WITH PINE NUTS, SPINACH AND SUN-DRIED TOMATOES

Serves: 6 / Preparation time: 15 minutes

Total time: 30 minutes

1 cup vegetable broth

1 cup dehydrated sun-dried tomatoes

1 pound spaghetti or thin spaghetti

2 tablespoons pine nuts

1 tablespoon olive oil

1/4 teaspoon crushed red pepper flakes

1 clove garlic, minced

2 tablespoons sherry

10 ounces fresh regular spinach, rinsed, tough stems removed, torn into bite-size pieces

1/3cup heavy whipping cream

1/4 cup grated Parmesan cheese

In a small saucepan, bring the broth to a boil. Remove from heat. Place the sun-dried tomatoes in the broth 15 minutes, or until softened. Drain, reserving broth, and coarsely chop.

Bring a large pot of salted water to a boil. Place pasta in the pot and cook 9 to 12 minutes, until al dente, and drain.

Place the pine nuts in a skillet over medium heat. Cook and stir until lightly toasted.

In a large skillet, add the olive oil, red pepper flakes and garlic and cook for about 2 minutes over medium heat. Stir in the sherry.

Mix in the spinach, and cook until almost wilted. Add the reserved broth, and chopped sun-dried tomatoes. Continue cooking 2 minutes, or until heated through. Stir in the heavy cream, and cook until thickened.

In a large bowl, toss the cooked pasta with the spinach and tomato mixture and pine nuts. Serve with Parmesan cheese.

From and tested by Susan Selasky for the Free Press Test Kitchen.

230 calories (34 percent from fat), 9 g fat (3 g saturated fat), 31 g carbohydrates, 7 g protein, 304 mg sodium, 13 mg cholesterol, 6 g fiber.