Aging Meat & Freezing Meat
Aging Meat & Freezing Meat
AGING - Aging of meat is done for two reasons: First and foremost, it is a tenderization process. Second, it produces flavors that are different from those of fresh meat.
What occurs during aging to make meat more tender? What develops the flavors? - Actually, in a manner of speaking the meat is kind of "digesting itself". You see even though the animal is dead, the cells in the muscle are still alive. They produce enzymes that break down protein as part of a normal body function of "tear down and rebuild". However, when muscle no longer has a blood supply, only the "tear down" part takes place. Enzymes called "cathepsins" break down part of the structural portion of muscle and make it more tender.
The unique flavors of aged meat come from lipid oxidation and protein lysis. What the hell is that? Well, lipid oxidation is actually the fat turning slightly rancid. Yup, rancid. Protein lysis simply means that the molecules are breaking into pieces and the pieces have different flavors than the whole protein....probably more than you wanted to know. This is a little important when we get to the topic of freezing tho'.
There are 2 kinds of aging: Dry aging and wet aging. I don't advocate wet aging for the simple reason that it often promotes the growth of too much bacteria and mold on the surface of the carcass. Considering we are talking about wild game here and it's often not processed under ideal conditions, it's much better and "food-safer" and utilize dry aging. Before I go into how to age meat, let me first explain more about why we age meat and why is sometimes NOT appropriate to age the carcass.
Muscle tissue contains connective tissues. The connective tissue proteins called "collagen" and "elastin" are what actually hold muscles, bones and other organs together in the body. As an animal ages, the molecules of connective tissue protein begin to "cross link". One strand of protein will bind to others nearby. As far as we can tell, this process continues pretty much throughout an animal's life, at least in ruminants. The older the animal, the more cross linking and the more toughness.
Kind of an interesting side note: Cross linking and the development of toughness does not occur at nearly the same levels in swine species. Because pork has more collagen and less elastin, meat from old pigs is only slightly tougher than the meat from young ones.
Here's the point where it may not be appropriate to age wild game - if you do shoot a yearling animal, whether is taken as a cull or shot for camp food, you may want to consider skipping the aging. One upside of not aging the meat is the flavor notes are a bit cleaner. It's your choice either way. (When I get around to typing out notes on meat prep, I'll give you a real simple 4-hour tenderization/hydration method that works every time. This is what I use instead of aging for yearling venison.)
Anyway back to the topic - Most of the animals we take are mature, adult animals. They are also not domestic critters that were bred and selected for over hundreds of generations to end up on our supper table. In point of fact, all the selection that has taken place has favored the fastest, strongest and toughest of them all. The meat will benefit from some degree of tenderization.
Dry aging is simple. There's two basic ways. The most trouble-free way is to get the meat chilled down (to about 35-40F) and get through the first 24 hours so rigor is complete as I spelled out in my first post. Then hold the carcass (still hanging by the hind legs) at that temperature for about 8-9 days. After 8-9 days, you can butcher as normal and cook or freeze the meat.
The faster way to age meat is to simply take the cooler temperature up to 50F and hold for 4-5 days. Again, it still has to be hanging by the hind legs. After 4 or 5 days, you can start butchering. For each 18 degrees F )10 degrees C) that you raise the temperature, you double the rate of chemical reactions. Enzymatic break down of connective tissue is a chemical reaction, so that's why the higher holding temperature ages meat faster.
For a long time in the meat industry, there was a belief that aging could not occur at lower temperatures. This is simply not true. There are numerous studies that have proven that aging tenderization even takes place in the vacuum sealed bags used for packing primal cuts. It just happens more slowly at lower temps.
OK, 2 notes right away about freezing meat:
1. Don't even THINK about freezing meat until the whole carcass has gone through rigor. I think I've spent enough time on the reasons why.
2. No piece of meat was ever improved by freezing. Fresh meat is ALWAYS better. When we freeze meat, the best we can hope for is not to damage it too much.
Here are the things to do get the best results when freezing meat and some of the reasons why:
A. PACKAGE MEAT IN AIR-TIGHT, MOISTURE-PROOF MATERIALS. Exclude air as much as is possible. Why? Even at freezer temperatures, fat can turn rancid. It just happens more slowly. Air is required for "oxidative rancidity", so keeping air out reduces off flavors. Also, believe it or not, water can evaporate off of the meat even at tempertures this low. Moisture proof containers keep water from being lost. The very best containers are the vacuum seal bags.
B. FREEZE AS FAST AS POSSIBLE. Why? The faster meat freezes, the smaller the ice crystals that form inside of the cells. Small crystals usually don't rupture muscle cells. Large crystals do. When you get cells ruptured, you lose way too much "meat juice" upon thawing. This results in dry, tough, chewy meat. As you would guess, piling meat in one spot in the freezer is a bad idea. Spreading it out or putting spacers between layers promotes much faster freezing. The VERY FASTEST freezing occurs when you put packaged pieces one layer thick on cookie sheets and alternate the freezer fill like this: meat layer-cookie sheet-meat layer-cookie sheet. Just make sure that air can circulate
C. THAW SLOWLY. Let a piece of meat thaw in the refrigerator until it is at least 32 F (0 C). If you don't have enough time to do that, use the old paperbag trick that your Mother used for thawing Thanksgiving turkeys. Just thaw the meat as slow as you can. Why? Even though juice comes out of ice-disrupted cells, there is some reabsorbtion by the contractile proteins, it just takes a little time.
D. KEEP IT COLD & DON'T KEEP IN THE FREEZER TOO LONG - The old "rules of thumb" are 6 months for pork and 9 months for meat from any ruminant. This is based on the typical home freezer running at 0 F. If your freezer will hold -20 F, you can hold the meat at least 50% longer than that. HOWEVER, if you aged your meat before freezing it, knock 1/3rd off of these numbers. Why? Because you already started oxidative rancidity of the fat with the aging process.
That's all for tonight. I think I'll tackle sausage-making basics next.