Dry aging beef was the most common means of enhancing beef tenderness and flavor before the advent of boxed beef.
Before the 1960s and the advent of widespread vacuum-packaged boxed beef, if tenderness and flavor of beef were to be enhanced by aging, the only real option was to use dry aging. Beef in carcass, primal, or subprimal form would be stored at refrigeration temperatures for several weeks to achieve the desired palatability endpoint. During the dry aging process, the surface of the beef would dry out causing a crust to form. Because water is the primary component of fresh beef (approximately 70 percent), beef loses a substantial amount of weight during the dry-aging process. When merchandising the dry-aged steaks and roasts, the price reflected the lost yield from product shrinkage and the amount of trimming required to remove the dried exterior surface from these products. When the beef industry shifted to aging beef as vacuum-packaged boxed products, evaporative and trim losses were reduced dramatically allowing improved saleable yields in the marketplace. Dry aging became a niche market for foodservice, and to a lesser extent, the retail industries.
Over the past two decades, there has been an increased interest in the dry aging process driven primarily from restaurateurs and retailers seeking unique ways to market their product. While there have been several scientific and review articles about dry aging during this time period, dry aging is still considered more of an art form where parameters have been developed mostly through trial and error rather than scientific or technical methods.
One point that is clear, whether beef is wet aged or dry aged, is that the improvement in tenderness through the aging process occurs independently of which style is used. Meat aging is the result of naturally occurring enzymes that are activated in the postmortem muscle whether the meat is held in a vacuum package or is exposed to air such as when dry aging is used. Therefore, the primary reason for dry aging beef is to impact flavor, not tenderness.
With respect to flavor, how dry aging works can be categorized into two primary areas: (1) concentration and (2) creation. Concentration of flavor is simple. The weight loss achieved during dry aging simply makes the beef flavors stronger because there is less water in the meat to dilute them. This is similar to the reduction process used when cooking various sauces and gravies by simmering them as a way to thicken and change the consistency and ultimately concentrate their flavor. Creation of flavor is more complex. Flavors are created as the chemical nature of proteins and fats change through various oxidation processes whereby new compounds are formed over time. These compounds may be slightly putrid and rancid, but not unlike the experience of eating various strongly flavored cheese such as the blue cheeses and sharp cheddars. From this aspect, the flavor of dry-aged beef can be an acquired taste, much like strongly flavored cheeses.
Regardless of the method used, beef aging is the result of naturally occurring enzymes that are activated in the postmortem muscle.
So what parameters are important for dry aging? Time, temperature, relative humidity and air flow are factors that are most asked about when people inquire about how best to dry age beef. How long beef is aged is the most important factor in dry aging. Simply put, the longer product is dry aged, the more product shrinkage and development of flavors occur. There is no magic time period for a product to be considered “dry aged,” but 28, 35 or 42 days would not be uncommon increments for dry aging beef. Today, most companies that dry age begin with vacuum packaged boxed beef subprimals because these are more available than unpackaged product, and the time period for dry aging often begins when the beef is removed from the package, which could be up to a week after the pack date on the box. It should be noted that most dry aging periods start at this point making the total aging period slightly longer than the dry-period alone.
Storage temperature does not seem to be a factor in dry aging. Most studies on dry aging have used typical refrigeration temperatures (30°F to 35°F); storing beef at elevated temperatures may create more quality/safety issues that outweigh any benefits. Relative humidity is another parameter that is frequently asked about with respect to dry aging. Again, as with storage temperature, there is no magic relative humidity for dry aging. Studies have used a range of values for relative humidity with most of them being in the 70 percent to 85 percent range. Relative humidity values outside of this range may impact the storage times for dry aging to occur and could impact quality and/or spoilage of beef.
Air flow is another key factor in dry aging. Making sure all surfaces of beef are allowed to dry ensures spoilage does not occur before the crust is formed. The crust forms a protective barrier that helps prevent spoilage bacteria from causing discoloration and off-odors and off-flavors for the beef cut. Establishments that dry age use wire racks, perforated shelves, and/or meat hooks or trees on trolleys to ensure all surfaces are allowed to dry age. It is not uncommon for some companies to physically rotate products during the dry-aging process to make sure all surfaces are exposed to drying. Good air circulation including using supplemental fans in the cooler help with the drying process.