The Union Recorder

Community News Network

September 9, 2013

Why is some deli meat iridescent?

Q. What causes some sliced deli meats to possess an iridescent sheen? On occasion, a slice of ham or beef will exhibit the sort of rainbow spot one might see on an oil slick or the inside of a seashell. Why?

               

A. It's because of the particular way light bounces off the surface of the deli meat, a phenomenon known as "diffraction." A piece of meat is composed of strands of fibers that are tightly packed together in parallel bundles. After meat is sliced, the cut ends of the fibers form a series of grooves, like the top of a picket fence. White light is composed of a spectrum of different colors, and each one of those colors has a specific wavelength. When white light hits the grooves on the surface of a deli meat slice, some of the light is absorbed and some of it is reflected. Each component color wave of the reflected light bends at a different angle depending on its particular frequency. The result of this spread of color waves is a kaleidoscope or iridescent effect, similar to the colors we see in soap bubbles, CDs and fish scales.

Diffraction depends on the grooves being structurally intact and perfectly aligned. This is why you're much more likely to see this rainbow effect on processed deli meat that's cooked and/or cured than on raw meat. The former has a firmer, tougher texture and the picket fence structure keeps its shape well when deli meats are sliced. Raw meat, on the other hand, is softer and more delicate, and the ends of the meat fibers are easily damaged when the meat is cut, which means that light is reflected in a haphazard way that doesn't result in rainbows.

So why do some deli meats shimmer while others remain dull? The color of the meat matters. Dark cooked meat like roast beef and bright cured meat like ham are more likely to show iridescence because the background colors provide a starker contrast to the pearly greens and orangey reds that you're most likely to see coming off of shiny meats. Turkey and chicken are too pale to showcase such sparkle. It also matters whether the deli product contains ground or "restructured" meat (in which chopped meat is molded together) or is composed of a single piece of muscle. In the former case, the jumbled up meat fibers are no longer aligned correctly to diffract light.

The way a joint of meat is sliced at the deli counter or before being pre-packaged is also paramount. Only cuts that are sliced against the grain, or perpendicular to the direction of the meat fibers, show iridescence, since the protruding severed ends of the fibers produce the fine grooves. (For beef, these cuts are brisket, which is used for corned beef, and top round, used for pastrami, and navel, used for roast beef.) The sharpness of the blade with which the meat is sliced makes a difference, too. The sharper the slicing instrument, the cleaner the cut, the smoother the surface, and the more intense the display of rainbow hues. Blunt knives produce rough surfaces; the picket fence grooves will be too disrupted to produce iridescence.

The commercial curing process can cause sliced deli meats to have an especially smooth surface, which is why you sometimes see dazzling rainbows on cured hams. Cured meats are first injected with a brine or marinade and then tumbled in revolving metal drums to allow the brine to penetrate evenly throughout the meat. This process causes proteins to seep out from cells and fill gaps between muscle fibers, creating an even, consistent texture that's more likely to diffract light when sliced.

Fat content also has an impact on the light-reflecting properties of meat: A particularly fatty cut of meat is unlikely to diffract light. A slice of roast beef that's richly and evenly marbled with fat won't shine. Fat is either liquid (at room temperature) or semi-crystalline (when chilled), and neither of these states possess the right grooved structure to create a rainbow sheen.

 Since diffraction is a purely physical phenomenon and has nothing to do with microbial growth, iridescent deli meat poses absolutely no safety risk, nor does it have any effect on taste. But this might not always be the case with raw meat, which can occasionally exhibit iridescence. Raw meats are more prone to bacterial contamination, and a colorful glow could be caused by light reflecting off a surface film of liquid produced by microbes. To determine whether your iridescent raw meat is unsafe, lightly wipe the surface of the meat with a paper towel. If the sheen disappears, then the meat is likely harboring slime-producing microbes, and you should discard it.

               

       

 

1
Text Only
Community News Network
  • The top 12 government programs ever

    Which federal programs and policies succeed in being cost-effective and targeting those who need them most? These two tests are obvious: After all, why would we spend taxpayers' money on a program that isn't worth what it costs or helps those who do not need help?

    April 22, 2014

  • In cuffs... 'Warlock' in West Virginia accused of sexual assault

    Police in West Virginia say a man claiming to be a “warlock” used promises of magical spells to lure children into committing sexual acts with him.

    April 22, 2014 1 Photo

  • Cats outsmart the researchers

    I knew a lot had been written about dogs, and I assumed there must be at least a handful of studies on cats. But after weeks of scouring the scientific world for someone - anyone - who studied how cats think, all I was left with was this statement, laughed over the phone to me by one of the world's top animal cognition experts, a Hungarian scientist named Ádám Miklósi.

    April 22, 2014

  • McCain 1 House Republicans are more active on Twitter than Democrats

    Your representative in the House is almost certainly on Twitter. Your senator definitely is. But how are they using the social network? Are Democrats more active than Republicans, or vice versa? Who has the most followers on the Hill?

    April 22, 2014 1 Photo

  • Do White Castle prices tell us anything about the minimum wage?

    The paper looked at how many delicious steamed sliders the minimum wage has been able to purchase over time. The point is that as it notes, in 1981, the $3.35 minimum could buy a whole dozen. Today, at $7.25, it could purchase just 10.

    April 21, 2014

  • VIDEO: Moose charges snowmobile, flees after warning shot

    While snowmobiling in New England, Bob and Janis Powell of Maine were charged by a moose and caught the entire attack on camera.

    April 21, 2014

  • Can Hillary Clinton rock the cradle and the world?

    What's most interesting to contemplate is the effect becoming a grandmother will have on Hillary's ambition. It's one of life's unfairnesses that a woman's peak career years often coincide with her peak childbearing years.

    April 21, 2014

  • Smartphone kill switches are coming

    Smartphones need kill switches. It's a relatively easy solution to the pricey (and irritating) problem of smartphone theft. But who would have thought that the big carriers would team up with Apple, Google, Microsoft, Nokia, Samsung and lots of other manufacturers to voluntarily begin adding the technology by July 2015? The cooperative spirit! It makes so much sense!

    April 18, 2014

  • Why do wolves howl?

    Of all the myths that dog the wolf, none is more widely accepted than the idea that wolves howl at the moon. Images of wolves with their heads upturned, singing at the night sky, are as unquestioned as a goldfish's three-second memory or a dog's color-blindness (both also myths).

    April 18, 2014

  • Biggest student loan profits come from grad students

    This week, the Congressional Budget Office projected that the federal government would earn roughly $127 billion from student lending during the next 10 years.

    April 18, 2014

Poll
AP Video
U.S. Paratroopers in Poland, Amid Ukraine Crisis US Reviews Clemency for Certain Inmates Raw: Violence Erupts in Rio Near Olympic Venue Raw: Deadly Bombing in Egypt Raw: What's Inside a Commercial Jet Wheel Well Raw: Obama Arrives in Japan for State Visit Raw: Anti-Obama Activists Fight Manila Police Motels Near Disney Fighting Homeless Problem Michigan Man Sees Thanks to 'bionic Eye' Obama to Oso: We'll Be Here As Long As It Takes Bon Jovi Helps Open Low-income Housing in Philly S.C. Man Apologizes for Naked Walk in Wal-Mart New Country Music Hall of Fame Inductees Named 'Piles' of Bodies in South Sudan Slaughter SCOTUS Hears Tv-over-Internet Case Chief Mate: Crew Told to Escape After Passengers
Facebook
Twitter Updates
Follow us on twitter
Parade
Magazine

Click HERE to read all your Parade favorites including Hollywood Wire, Celebrity interviews and photo galleries, Food recipes and cooking tips, Games and lots more.
Stocks
NDN Video
Stephen Colbert Tells David Letterman His Plan for 'Late Show' Viral: It's Not Pitbull - It's Amy Poehler! Georgetown police officer filmed tripping students Lupita Nyong'o Named People's 'Most Beautiful' Recycling Highlights for Earth Day Peeps Launched into Outer Space NYPD's Twitter Request For Photos Backfires New HBO Go Commercials Capture Awkward Family TV Watching Raw: Leopard Bites Man in India Rise of the Milkbots Jenna Dewan-Tatum Strips Down TRENDING: Brian Williams Raps 'Gin and Juice' on ‘Tonight Show’ Middle School heroes rescue students from burning bus WHOPPER OF FISHING STORY: Florida man catches massive Mako shark Maks Chmerkovskiy's "DWTS" Meltdown The many faces of Mike Woodson Ape Builds A Fire And Toasts Marshmallows In Amazing BBC Video Manchester Utd sack manager David Moyes "RHOA's" Dramatic Brawl High school, College Drug Ring Busted In Montgomery County