How to Know If Roast Beef Looks Good or Bad

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Once the date on the label passes, you begin to inspect your roast beef with a little more scrutiny, poking, sniffing and prodding the meat for signs of mysterious and all-too-ominous spoilage. You may want to dial down your trepidation; however, the “sell by” and “best by” dates on food, including commercially packaged roast beef and cold cuts from your grocer's deli, have more to do with taste than food safety. By and large, your own senses serve as the most reliable means of determining edibility and freshness.

Changing Colors

Most likely, your first inspection of questionable roast beef will be visual. Don't feel too alarmed if the meat isn't the exact same color as it was when you bought it; according to the USDA, color changes, a result of simple oxidation, are normal for meats. More often than not, your roast beef will fade or darken after a bit of time in the fridge, so visual inspection alone isn't enough to determine whether or not you should slap the roast beef on a sandwich.

Telling Textures and Suspect Smells

Although color isn't the end-all indicator of freshness, a noticeable translucent sheen typically indicates bad roast beef. In the same manner, if the beef feels slick or slimy to the touch, it's time to toss it. Past-due roast beef may also have a sticky or tacky texture. Finally, after inspecting and touching the cold cuts, give your roast beef a whiff; your nose is your most valuable tool in determining the usability of food. If the meat smells off or puts off a sulfurous, foul or otherwise rotting odor, it's no good.

The Truth About Rainbows

While a clear sheen is bad news, the oft-feared “rainbows” that appear on roast beef slices don't pose a threat. Unlike a slimy coating, these rainbows appear greenish, coppery or iridescent. While it certainly looks strange, this phenomenon occurs as a result of light hitting the meat and causing an effect known as "diffraction grating," the same process that gives your DVDs a rainbow-like appearance. Iridescent hues do not indicate spoilage or poor quality.

The Life Span of Lunch Meat

While the look, feel and especially the smell of roast beef clue you in to its freshness -- or lack thereof -- taking its typical shelf life into account helps you make the safest possible choice. For the longest-lasting roast beef, keep your meat refrigerated and sealed tightly in plastic wrap or aluminum foil. When refrigerated, roast beef from the deli counter or in an open package of commercial cold cuts typically lasts about three to five days, while unopened packaged beef lasts for about a week after its “use by” date. Sealed in an airtight container in the freezer, roast beef can last upward of two months, or indefinitely when frozen constantly at 0 degrees Fahrenheit.