Dry aging prime beef occurs while the beef is hanging in a refrigerated cooler, at a specific temperature and humidity, for 10 to 28 days after harvest and prior to cutting. When prime beef is dry aged, two things happen. First, moisture evaporates from the muscle meat creating a greater concentration of beefy flavor and taste. Secondly, the prime beef’s natural enzymes break down the fibrous, connective tissue in the muscle, tenderizing it. Most of the tenderizing activity occurs within the first 10 to 14 days.

Some high quality restaurants will age their meat for 28 days or more. More aging adds to the shrinkage and trim loss due to the drying and surface mold. Up until 20 years ago, dry aged prime beef was a normal process, then with the advent of vacuum packaging along with increased efficiencies in beef processing and transportation, we lost the dry aging process.

In today’s modern processing plants, the meat is broken down and vacuum-sealed in plastic bags within 24 hours. Much of this prime beef will show up in a grocery store meat case within 2 to 4 days after harvest.

Beef can be "wet aged" in a vacuum-sealed plastic bag for improved tenderness but it will not have the same characteristic as dry aged flavor. Because refrigerated storage is more expensive, only the high priced loin and rib cuts are aged (wet or dry).

It's been decades since butchers first discovered that beef carcasses, left hanging for several days, ended up more tender and delicious as natural enzymes in the meat broke down proteins and connective tissue. Today the "wet" process is mainly used for aging steaks. Wet aging is done by leaving the beef to age in a vacuum packed bag.

Dry aging was big in the 50's and 60's, and then the market moved to the less-costly boxed beef and vacuum packaging. 99% of Supermarkets today sell boxed dry aged prime beef. In the 80's, dry aging enjoyed a rebirth. Dry aged prime beef steak is aged in the open air at controlled temperature between 34 F and 38 F with a humidity level adjusted between 50% and 75%.

Wet-aged meat is put in a vacuum-sealed bag. Dry aged prime beef requires 7 to 14 days or longer to age properly. Wet-aged beef can mature in as few as 7 days. Meat is muscle, and muscle is made up of protein structures that break down with the aging process.

The result is that you will have more tender cuts of meat and more flavor. It's the good bacteria within the meat itself that causes the degradation. Air circulation is essential in managing dry aging and is perhaps the main reason why dry aged prime beef costs substantially more, since the resultant evaporation causes significant shrinkage. Common shrinkage is 10 to 15%. And dry aged prime beef usually cost about 25% more than wet aged prime beef.