Can you expand even more on the dry aging details. I am rather flabbergasted at the suggestion of up to 300 days! How does it keep from spoiling?
It's controlled decomposition. The USDA notes that there is ZERO flavor change until 30 days of dry aging. Peak tenderness is achieved at 28 days. Yet when you buy dry-aged steak from a meat locker or store, its usually 7 day dry aged, a worthless scam.
The steak agers have a few mechanisms at work. First, you're dry aging around 35-38F, above freezing so live bacteria can develop, but below 40F, the temperature where harmful bacteria can exist. In addition, they have a UV light that sterilizes dangerous pathogens on the meat. They also have a humidfication system to slow evaporation within the steak. Some will also have blocks of Himalayan sea salt that kills some bacteria and adds a bit of salinity to the meat.
What is actually happening to the dry aged beef? First thing that happens is a reduction in moisture which consolidates that beefy flavor. Just that activity which results in about 15% weight loss over a long dry age period creates a better taste profile. The second thing that happens is that the fats break down and become that delicious, edible, soluable fat you get out of a standard Ribeye but exists nowhere on a NY or KC Strip loin when fresh. The fat starts to get that nice, flaky texture and when grilled you will eat every bite of the fat that has that fantastic, buttery, best-part of the experience taste. The third thing that happens is a matter of personal taste preferences. At about 45 days you get a very subtle, delightful "funk" on the meat that 99% of people enjoy. At 60-75 days that grows to a point where 90% of people enjoy it, noting taste of black truffle or really good quality mushrooms in a positive sense of the term. Strong notes of nutty taste are present. When you go past those timeframes the steaks become pungent and opinions begin to diverge, some finding them unpleasant or at least unexpected to a normal palate. I've tried everything up to 300 days and I've personally dry aged steaks up to 125 days. I personally do not think the 90-125 day dry aging is worth the squeeze. The flavors aren't really developing that much yet you start getting a LOT of meat loss as the edge margins oxidize and become basically meat-jerky that reduces the weight of the edible steaks you'll cut from the primal.
The very best steaks I've dry aged turned out to be this process. 1.) I would buy a primal T-Bone in that 10-15 pound range. 2.) I would have the butcher open the cryovac and use a bone saw to cut the bone-in Filet Mignons off of the primal and cut them into 2" thick steaks. (Those I'd eat immediately, the very best filet mignon you will ever have) 3.) I would take the primal "strip loin" remaining that had the L shaped bone in it and a huge fat cap on it, placing it into the dry ager for 75 days.
The Primal Kansas City Strip loin above is ideal, it has the best bone and membrane to prevent moisture loss on two sides, the best fat cap to slow evaporation on the third side. The two exposed ends are where moisture loss primarily occurs although I'm told you can dip the ends in warm tallow several times to seal the ends, yielding more finished product.
What to do with the dry-aged bones? Absolutely spectacular if roasted and then used for bone broth, espanole, or demi-glace.
What do you do with the pellicle? Pellicle is the dry fat and meat chunks that you carve off the primals at the end of the dry aging when you cut your steaks. The pellicle can be soaked in au jus, beef broth, or bone broth overnight in a fridge. The next day, you add 20%-25% pellicle to your grind when you make ground beef. You ever hear about those $1000 hamburgers at the michilen star restaurants in NYC? Yeah, that's what's in them. That's what Pat Lefreda does on his most expensive ground beef as well.
I'm not much of a ground beef guy these days, I find it ludicrously expensive for what it is at present market prices. You know what is cheap these days? Prime Brisket at Sam's club is spectacular and its $5 a pound. Dry aging a prime brisket 45 days and then grinding it for burgers would put you at <$7 a finished pound and would trump any ground beef on the planet for the same exact price.