A Staff Report from the Straight Dope Science Advisory Board

What's the big deal about aged beef and Angus beef?

August 23, 2005

Dear Straight Dope:

What's the deal with aged beef? Sounds suspiciously like a euphemism for "old meat" to me. Seems like the last thing you'd want to do with a hunk of dead animal you intended to eat would be to let it "age" for any appreciable amount of time. Presumably there's more to it than just leaving it in the fridge for a few months. So what gives?

Dear Straight Dope:

Certified "Angus beef" seems to be all the rage these days. Is it just a buzzword, or is it as something distinguished as the commercials would have me believe?

I wondered about these questions myself, so I decided to do some research and find out the answers for all of us. The first thing I looked at was why we age beef. I agree that the idea of aging beef to improve the taste sounds fundamentally wrong. We expect that most foodstuffs, with a few exceptions such as wine and cheese, taste best when fresh. However, it turns out that aging can be beneficial to both the taste and texture of beef.

Directly after cattle are slaughtered, their meat is generally quite tender, which is one reason people like fresh-killed meat. However, since few restaurants adjoin a stockyard, most of us have to settle for meat that's not nearly as fresh. During the first 12 to 24 hours postmortem the meat will toughen as the muscle fibers shorten due to rigor mortis. After that, however, enzymes in the meat attack the structural proteins that make meat tough (a process called "postmortem proteolysis"), resulting in slow and natural tenderization. The process happens quickest in pork and lamb and generally slowest in beef. Enzyme action has the additional effect of improving and strengthening the flavor of the beef, most likely due to the breakdown of proteins into amino acids.

Since aging would normally allow bacteria and mold to act on the beef, it's carried out at low temperatures, generally between 34 and 38 F. Beef can be aged anywhere from a few days to as long as six weeks, with the average probably around 10-14 days in an effort to strike a balance between taste and storage costs. Aging is typically done by the so-called dry method, where the beef is hung in a freezer for a prescribed time prior to cutting. Dry aging results in a loss of meat over time due to water evaporation and surface mold (which must be trimmed off), but is said to concentrate the flavor of the meat. An alternative method is wet aging, where the meat is stored in large vacuum bags that seal the moisture in and keep some of the mold out. Wet aging reduces the loss of meat due to evaporation and mold, resulting in more saleable meat, but generally doesn't develop an agreeably strong taste to the degree that dry aging does.

Aging beef is an ancient practice that surely began out of necessity--drying (or smoking) meat was the only way to preserve it in pre-refrigeration days, although people no doubt realized early on that it could improve flavor and texture. Sometimes the process can be taken to extremes. Food writer Harold McGee reports, "In the 19th century, beef joints would be held until the outside was literally rotten; the French called this mortification."

Now let's talk about Angus beef. I've wondered what Angus beef was ever since I was young, growing up near a cattle pasture that featured a huge roadside billboard advertising "BLACK ANGUS." (Said billboard was once the unfortunate target of a high school prank in which the "G" was painted over, but I digress). It happens that Angus is a breed of cattle, originally hailing from Scotland, that has an official designation given to it by the U.S. government. According to the U.S. Department of Agriculture (USDA) Agricultural Marketing Service, Angus beef must meet the following requirements:

2.1 Genotype. Cattle eligible for Angus influence beef programs based on genotype must have positive identification (ear tags, tattoos, brands, etc.) and be traceable back to provable (e.g.; registration papers) Angus parentage. Qualifying cattle must be traceable to one registered parent or two registered grandparents. Programs which claim a specified percentage of Angus heritage must use this method.

2.2 Phenotype. Cattle eligible for certification in Angus influence beef programs based on phenotype (appearance) must be predominately (51 percent) solid black. Blue roan, gray, etc., are not considered to be black or a percentage of black. Such variations can qualify only when it occupies 49 percent, or less, of the body area with the remaining 51 percent, or greater, being solid black. (1) Angus influence cattle may be either horned or polled. Carcasses of certified live animals which display certain non-Angus characteristics (e.g.; dairy conformation, Brahman humps) shall be excluded as specified in the carcass specifications for approved programs.

(1) At times, a black hair coat can become sun bleached and appear to be a shade of brown, particularly on the back. If the base of the hair close to the skin is black then that entire brown tipped area should be considered solid black. However, if the hair color is brown to the roots, it should be considered as brown in color and the area will not contribute to the 51 percent black requirement.

"Certified Angus Beef" (CAB) is a special industry designation developed in 1978 that involves standards for marbling, tenderness, age, and color. According to the National Cattleman's Beef Association, only about 8% of U.S. beef is entitled to the label "Certified Angus." Just because something is labeled "Angus" or "Black Angus" doesn't mean it's the same quality as "Certified Angus Beef." Angus beef is further differentiated by USDA grades such as "prime," "choice," and "select," giving us such labels as "Certified Angus Prime," indicating the best Certified Angus Beef.

That tells us what qualifies as "Angus" but not why we would want Angus beef. A lot of it comes down to genetics--specifically, the genes that control a protein called myostatin. Myostatin inhibits the growth of muscles in cattle. According to David Elstein and Erin Peabody (see reference below), "If the gene responsible for producing myostatin is altered so that it makes an inactive form of the protein, or the gene is intentionally suppressed, the result is more muscle and less fat." Angus and Hereford cattle have more myostatin, so their meat is fattier and more marbled. But fat content and marbling alone don't tell you if the meat is likely to be tender--you have to look at other things, such as how fine the marbling is and how well distributed through the meat, and the toughness of the fat and connective tissue. Here again there is an advantage for Angus beef, as it tends to have finely textured marbling and thus can be more tender than meat from other breeds.

Marbling of meat figures prominently in USDA beef grading standards, as this excerpt shows:

Quality Grades:

  • Select grade - is very uniform in quality and normally leaner than the higher grades. It is fairly tender, but, because it has less marbling, it may lack some of the juiciness and flavor of the higher grades. . . .
  • Standard and Commercial grades frequently are sold as ungraded or as "store brand" meat.
  • Utility, Cutter, and Canner grades - are seldom, if ever, sold at retail but are used instead to make ground beef and processed products.

USDA meat grades are illustrated in the following chart. Note that when they refer to "maturity," they are referring to pre-slaughter age, not post-mortem aging. Category A, for example, is typically from cattle that were less than 30 months old when slaughtered.

Another breed of cattle with finely marbled meat is Wagyu cattle, one variety of which gives us the very expensive "Kobe beef." According to the USDA, some Wagyu cattle can have body fat content of as much as 45%, although most sources say the average is considerably lower. A more useful measure of fat content is done at the ribeye region--measured at that location, Wagyu cattle often score in the range of 20-30% fat content (in contrast, USDA Prime beef often contains about 6-8% fat in the ribeye region). Due to the fine marbling and other factors, some cuts of Kobe beef are said to be the most tender money can buy, greatly exceeding the standards of beef tenderness and quality set by the USDA. 

Kobe beef is the subject of many stories about the treatment of the animals, some of which sound like urban legends but evidently aren't:

  • The cattle are given beer in their feed, primarily in the summer to increase appetite to help maintain their prodigious weight. It's not a universal practice; sometimes cattle only get a beer ration if they show an appetite loss.
  • The cattle are massaged by human handlers in the belief that this will relax the beef and make it more tender. Whether or not this works is unknown--some claim the real reason for the massages is limited space in the feedlots that prevents proper exercising of the cattle. Some American producers of Kobe beef admit they don't massage their cattle.
  • The cattle are brushed frequently with rice wine. This is done to improve their coats, allegedly because it leads to a healthier animal and more tender meat, although more likely because the glistening sheen makes for a higher price at sale time.

The question arises: How important is improved tenderness, and does it make much of a difference in taste? . The USDA report "Food Consumption, Prices, and Expenditures, 1970-97" offers some interesting insight:

Beginning around 1960, in response to concerns about fat and cholesterol, beef producers began shifting production from the very fat English breeds like Hereford and Angus to the bigger, rangier, less fat, faster growing exotic breeds. This shift led to increasing inconsistency in the quality of beef - a less tender, less juicy, less succulent product. By 1995, one of four steaks was too tough to chew, according to the 1995 National Beef Quality Audit.

In addition, the mass entry of women into the paid labor force has drastically reduced consumption of beef roasts and other beef cuts requiring lengthy cooking times.

Some sources speculate that women prefer more tender meat due to their smaller teeth and weaker jaw muscles. Combining that with the reduced number of women staying at home to cook roasts and such, we can argue that women are a primary driver of the move to Angus beef in the U.S.

Is there a noticeable difference in taste between beef from different breeds of cattle? That question is difficult to answer. Much of the flavor of beef at the table is a result of the cooking process, and improper preparation of even Kobe beef is said to make it taste no better than the typical $1 per pound supermarket standard. I've had Kobe beef and didn't notice anything special or unique about it other than the $60 price tag for a 6-ounce filet. I frequently buy "Certified Angus Beef" for home grilling, but to tell the truth other than some improved tenderness I don't find it much different from the USDA Prime I would otherwise buy. Note that if you're using the beef in spicy dishes or curries, or grilling with a strong marinade or grilling rub, any special flavor of the beef itself will be largely lost. .

Friends and co-workers claim they can always tell the difference between types of beef and so buy nothing but Certified Angus Beef, but some of them are undoubtedly engaging in a bit of beef snobbery. Some people genuinely prefer leaner beef and don't care for the taste of marbled meat, so generalizations are difficult. I think the most one can say is that due to increased marbling, better texture, and more rigorous quality control, Angus and Kobe beef are more likely to taste better than standard beef to most meat-eating palates.


"Beef Tenderness: Regulation and Prediction," M. Koohmaraie, T. L. Wheeler, and S. D. Shackelford, USDA-ARS U. S. Meat Animal Research Center, 1995

"Can you have your beef and eat it too?" David Elstein and Erin Peabody, Agricultural Research, July 2004.

"Food Consumption, Prices, and Expenditures, 1970-97," Judith Jones Putnam and Jane E. Allshouse. Food and Rural Economics Division, Economic Research Service, U.S. Department of Agriculture. Statistical Bulletin No. 965.

"Is it Prime? Choice? Corn-fed? Grass-fed? Angus? Certified Angus?" Ed Murrieta, Tacoma [Wash.] News Tribune, Sep. 22, 2004.

Kobe Beef of America website, http://www.kobe-beef.com 

National Cattleman's Beef Association Website, http://www.beefusa.org/ 

On Food and Cooking: The Science and Lore of the Kitchen, Harold McGee, 1984.

United States Department of Agriculture, "Certified Beef Programs"

United States Department of Agriculture, Food Safety and Inspection Service Factsheet, "Inspection & Grading - What Are The Differences?"

United States Department of Agriculture, Agricultural Marketing Service, Livestock and Seed Division, "United States Standards for Grades of Carcass Beef." Effective date January 31, 1997.

United States Department of Agriculture, Schedule GLA (Generic Live Animal), Nov. 1996. "USDA Specification for Characteristics of Cattle Eligible for Approved Beef Programs Claiming Angus Influence." Approved Nov. 6, 1996; Effective Jan 1, 1997

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