what does dry aging beef do

The dry-aging process allows the meat’s natural enzymes to break down the connective tissue, resulting in a more tender steak. The process also causes the meat’s moisture to evaporate, intensifying the beefy flavour and creating a unique taste and texture.

Dry-aging beef is a process that involves hanging freshly slaughtered beef in a temperature-controlled environment for anywhere from a couple of weeks to several months or more before being trimmed and cut into steaks. During this process, naturally-occurring chemical changes, including bacterial, enzymatic breakdown, and oxidation, cause the meat to become more tender and flavorful. It is the depth of flavor and tenderness that creates value and sets dry-aged beef apart from what is found in the average grocery store.

There are three primary changes that occur to beef when it goes through the dry aging process.

The first major change that will occur to beef during dry-aging is tenderization. The enzymes that are naturally present in the meat will break down the tougher muscle fibers and connective tissue, resulting in a very tender piece of meat. In fact, a well-aged steak will be significantly more tender than a fresh steak.

The second noticeable change is to the flavor. This change is due to numerous bacterial and enzymatic processes that make the meat more flavorful. Properly dry-aged meat will develop beefy, nutty, and almost cheese-like aromas.

The third change that occurs to meat during the drying process is moisture loss. A dry-aged piece of beef can lose a third of its initial volume in water loss, which concentrates its flavor. Most of this moisture loss occurs in the outer layer of the meat, which is trimmed off after the drying process and for preparation before cooking. Though it may weigh less after the drying process than wet-aged beef, or meat you find in the grocery store, the result is a premium cut of meat that is much more flavorful and tender.

The Experiment

To start my testing, I decided to follow the basic Cooks Illustrated/Alton Brown protocol: take fresh steaks, wrap them in several layers of cheesecloth or paper towels, place them on a rack in the back of the fridge, and let them sit for up to four days.

what does dry aging beef do

For thoroughness sake, I repeated the experiment a total of four times (twice with ribeye steaks, twice with tenderloin steaks) with six steaks in each batch aged for nine days, seven days, five days, two days, one day, and zero days.

I knew that in order for the taste test to be fair, the steaks would all have to come from the same steer, so I cut up a couple of boneless ribeye roasts that were donated by our friends at The Double R Ranch into identical steaks along with a couple of whole tenderloins purchased from my local Fairway butcher counter. But there was immediately a problem: How do you age some steaks and keep the others fresh?

The only way I know of keeping steaks fresh for a significant period of time is to freeze them, but this posed problems of its own.

what does dry aging beef do

See, when meat freezes, the water inside its cells forms ice crystals. This is good news for halting any sort of organic changes in the meat—without water activity, most bacteria and enzymes are rendered completely inert—but it can also cause some of those cells to rupture, which can, in turn, cause juices to spill from the meat as it thaws. A frozen-then-thawed steak will naturally be slightly mushier and more prone to moisture loss than a previously unfrozen steak.

what does dry aging beef do

I decided to compensate for this by carefully Cryovac-ing and freezing all of the steaks. Once frozen, they should remain completely inert until I defrost them. In this way, I made sure all of them were on a level playing field to start. As a control, I also included a freshly-bought, previously-unfrozen steak in my lineup on tasting day. It wouldnt be from the same steer, but it would at least give me a point of reference.

When youre lucky enough to have a job you love doing, the only real difference between messing around in the kitchen and doing real work is in the measuring, so I pulled out my scale, weighing every steak before I began the aging process. Every day, Id pull out a new steak from the freezer, let it defrost in its Cryovac bag in water kept at 40°F (4°C), wrap it in either cheesecloth or paper towel (as the case may be, depending on the specific experiment number), and place it on a rack in the fridge.

what does dry aging beef do

“What is this? A dry aging room for ants?” my wife said a few days later as she went in for the milk. Indeed, over the next several weeks, a collection of steaks at various stages of aging began to populate my fridge in waves. I spent my days thinking of ways I could slip the line, “You should check out the science experiment I found in my fridge the other day,” into conversation.

what does dry aging beef do

On the 9th day of each round of testing, I removed the steaks from the fridge, carefully unwrapped them, and weighed them again in order to ascertain degree of moisture loss.

what does dry aging beef do

The oldest steaks clocked in at around 7% weight loss, while the day old steaks barely broke 3%. Far more noticeable was appearance. While the freshest steaks had creamy white fat and a bright, wet-looking wetness on their cut surfaces, the older the steaks got, the darker their color and the tighter their appearance became, an indication that indeed, water was leaving them, concentrating their flesh.

what does dry aging beef do

Now, Im not the kind of guy to accidentally overcook a steak. And I say this with no hint of arrogance or smugness (there are plenty of other things I am smug about, like my video game skills), but merely as someone who stopped overcooking their steaks way back when he bought his first Thermapen thermometer. Still, Im not one to gamble on a couple weeks worth of work lightly, so I decided to split all of my steaks in half before cooking, just in case.

what does dry aging beef do

This ended up revealing a very fascinating cross-section:

what does dry aging beef do

The photo above is the cross-section of a fresh, unaged piece of beef. If you look very closely, youll see that the very center has a distinct purplish cast to it, while the outer layers tend to be a darker, cherry red. This has to do with oxygen penetration and the conversion of myoglobin to its various forms.

In its native state, myoglobin forms a compound called deoxymyoglobin. This is the purplish color of freshly cut meat, before its been exposed to any of our atmosphere. Let this purplish, cut surface sit in the presence of oxygen for long enough, and itll turn into oxymyoglobin, that familiar red color we look for in fresh meat.***

***Falsely look for, I might add, as color is an indication of atmosphere, not freshness.

Now take a look at the cross-section of the aged steak:

what does dry aging beef do

Youll notice immediately that the purple core is significantly smaller, and its soon followed by a brownish layer, and finally a dark, cherry-red layer on the exterior. Whats going on here?

Its a matter of timing. The brown color is the color of metmyoglobin, the form that oxymyoglobin converts to after prolonged exposure to oxygen. In the case of this steak, oxidation has penetrated deep enough and far enough into the steak as to create a significant ring of deoxymyoglobin. Meanwhile, the very outer layers of the steak have taken on a deep, dark red color, an indication that moisture loss has led to an increase in density around the edges of the steak, and therefore an intensification in color.

What this also tells us is that in the timeframe were talking—up to a week or more—small molecules do indeed penetrate deep into a steak. Is it possible that some of those molecules might be affecting flavor? And what about that dried out edge? How would that affect texture and flavor?

A quick gag-inducing sniff test proved the worst in the case of the nine-day aged steaks: They were all rotten. Even cutting into them revealed a core of edible meat only a few eighths of an inch thick. I threw them out, rather than risk the health of my tasters.

Result Explanation

So why cant a steak develop good dry-aged flavor in the home kitchen? Again, the experts disagree. My personal theory, and one that is shared by a number of others, is that the flavor changes in dry-aged beef—those funky, nutty, cheesy aromas that develop—come largely from bacterial action on the surface of the meat. This makes sense to me, as those flavors are most powerful near the cut edges of a steak, or near the bones, whose porous structure makes it easier for bacteria to get a foothold. The remainder of an aging primal is either covered in a thick layer of fat, or is made of muscle, which dries out and forms a cuticle that becomes impenetrable to moisture or bacteria after the first couple weeks of aging. (As a result, an aging primals moisture loss will slow to a crawl after this cuticle is formed.)

what does dry aging beef do

According to Pastore, the fauna that populates the surface of the meat and causes these flavor changes has to be abundant in the air to begin with for optimal effect, much like Spanish Jamón Serrano makers or Italian prosciutto producers say that aging a ham amongst other hams is essential for its flavor development. “You need to age meat with other meat so that their flavors can build together, not with cheese. In your fridge, youve got onions, cheese, vegetables, condiments. All that stuff that can give it off-flavors or worse, inoculate it with dangerous bacteria.”

This certainly rings true with taste test results in which tasters complained of off-putting, “old butter”-like flavors in fridge-stored steaks.

Steingarten has another take, saying that he believes the flavor change to be largely enzymatic—that is, caused by chemical catalysts that are naturally present in the meat to begin with. This is a difficult theory to test without an irradiated piece of beef and the sterile environment of, say, a microchip manufacturing plant. Unfortunately we cant even keep the darn dogs out of Serious Eats World Headquarters, much less the microscopic bugs.

An even more important factor is the obvious: surface area to volume ratio. With a large primal cut of the type that is used for aging in a steakhouse or specialty meat purveyor, the amount of meat you actually lose to moisture loss or hyperactive bacteria is—at least ratio-wise—quite small. Even after trimming a good inch or two off the surface of a prime rib, youre still left with plenty of serve-able meat underneath.

With a single steak, or even a trimmed rib roast that youd be able to find for home consumption, on the other hand, this ratio is exaggerated. With a 1 1/2-inch thick steak, you might lose over 50% to rid yourself of overly rotten bits if you were to attempt to age it for a very prolonged period of time. (Even after nine days, long before experts say aging offers any benefits, only a small sliver of edible meat was left in the center of a steak.)

what does dry aging beef do

Browning Qualities

I cooked the remaining steaks in a large cast iron pan, using an infrared thermometer to ensure that the surface temperature of the pan was identical before placing the meat inside it.

what does dry aging beef do

Normally, Id cook my steaks by flipping them frequently in order to promote faster, more even cooking throughout the meat. In this case, however, I stuck to a single flip in the middle for the sake of easy repetition and accuracy.

My goal was to cook them all to 120°F / 49°C (right around medium-rare), but even before I started taking their temperature, I noticed one major difference in their cooking quality: The completely fresh steak showed reduced browning properties. Take a look at the steak on the right versus the one on the left below.

what does dry aging beef do

This happens for two reasons. First, more moisture can cause it to buckle and bend when that moisture suddenly starts to leave (thanks to the heat of the pan), causing certain areas of the steak to shrink faster than others. Small perturbations in the surface of the meat are amplified.

Second, because those browning reactions (collectively known as the Maillard reaction) take place when proteins and sugars are heated to high temperatures—generally in excess of 300°F (149°C) or so. Meat contains a lot of water, which acts as a built-in temperature regulator, preventing the meat from getting too hot until it mostly evaporates. So for completely fresh meat to brown properly, this surface moisture must first be driven off. Meat that has spent time in the refrigerator, however, already has a dry surface, allowing it to brown more efficiently.

Slow browning is not the end of the world—just by letting the steak sit a few seconds longer on each side, I easily compensated for the discrepancies. Even more interestingly, the biggest difference in browning was between the non-aged steak and the one-day aged steak. After that, there wasnt much difference, no matter how long the steak was aged.

what does dry aging beef do

Indeed, subsequent testing showed that even an overnight 8- to 12-hour rest on a rack in the fridge is sufficient to create a dry enough surface on the meat for optimized browning.

H. Alexander Talbot and Aki Kamozawa of the blog and book Ideas In Food cited similar results in an email to me. “We found air-dried makes a difference. Certainly much better browning. but no real funkiness. The tender issue is debatable. The drier exterior seemed to make the interior feel moister and more tender. But we did not taste blind in this case.”

Other than browning, I noticed no major differences in the way the steaks cooked. The real surprise came after I weighed all of the steaks post-cooking to see how much moisture they lost from their original state.

what does dry aging beef do

Well, would you look at that? Turns out that whether aged for seven days, zero days, or anything in between, once the steak is cooked to 120°F, the moisture loss levels are pretty much identical. What this means is that whatever moisture loss occurs in the very outer layers of the steak due to dehydration during aging would have been lost anyway during cooking.

It also indicates—even before tasting—that any arguments that rely on the concentration of meat flavors due to moisture loss are most likely bogus, since the final moisture loss is identical in all the steaks across the board.

How would they stack up in actual blind tastings?

The dry-aging process allows the meat’s natural enzymes to break down the connective tissue, resulting in a more tender steak. The process also causes the meat’s moisture to evaporate, intensifying the beefy flavour and creating a unique taste and texture.

FAQ

What is the benefit of dry aging beef?

Simply put, dry-aging improves steak in two ways. During the dry-aging process, some moisture is expelled and redistributed in the steak, enhancing the flavor and tenderizing the steaks. Dry-aging steak results in a distinctive flavor that have been described as a rich and dense beefy flavor.

How does dry-aged beef not rot?

During the aging process, moisture is drawn out of the meat, which helps to create the umami flavor and tenderness of the beef. The lack of moisture also helps to make it hard for harmful bacteria to grow. These aging refrigerators are free of harmful bacteria and keep cold, dry air circulating.

Does dry aging make meat taste better?

Dry-aging steak is an age-old practice, used to keep meat fresh before refrigeration was invented. In the last decade, there has been a resurgence of dry-aging and steak connoisseurs have started to understand all the benefits of dry-aging steak. Dry-aging significantly improves the taste and tenderness of the meat.

How is meat dry-aged without going bad?

Using a dry-aging chamber, butchers and steakhouses can keep the beef free of harmful bacteria with cold, dry air circulation. Hanging the beef within the chamber, the entire surface of the meat is exposed to dry air that forms a protective crust. The lack of moisture makes it difficult for the beef to spoil.

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