Frozen Meat 101

I don’t know about yours but as far as my freezer is concerned, besides some frozen fruits, it’s stocked with meat. It’s so convenient to have it there. When I arrive home late at night, I can always resort to my freezer for some chicken or turkey meat.
But I never cared that much about the freezing process of meat. I just threw it in the freezer in after buying it and forget about it until time had come to eat it.
However, I recently discovered that there are several different methods of freezing and, moreover, that physical and chemical reactions can still occur in meat during storage in freezer.
The more I red about it, the more I realized how little I knew and that it was about time to fill this gap.



What happens to meat when it’s frozen

Freezing is one of the most effective methods of preserving meat. When meat and meat products are stored at temperatures below 10˚C (14˚F), microbial growth and enzyme reactions are essentially curtailed, and hence, quality loss is minimized.
However, physical and chemical reactions can still occur in meat during freezing, storage, and subsequent thawing.
Chemical changes in frozen meat during storage include discoloration and development of oxidative rancidity (which result from oxidation of myoglobin and unsaturated lipids, respectively) and texture hardening due to protein denaturation and aggregation.
These events are influenced by the rate of freezing and thawing, the duration of frozen storage, fluctuations of the freezer temperature during storage, and the atmospheric condition of the frozen meat.
When it comes to the processed meat (such as deli meats), the ingredients added to the meat (such as nitrates) and the specific processing procedures, such as grinding, chopping, emulsification, and restructuring, can influence the quality and shelf life of the frozen products. Also, antioxidants are often added to inhibit salt-induced oxidation in frozen meat products.

Protein denaturation

Freeze-induced protein denaturation, a main side effect of frozen meat, is attributed to physical damage resulting from the formation and accretion of ice crystals, and from chemical processes associated with dehydration and concentration of solutes in the muscle tissue. Freeze-induced protein denaturation is especially notable under slow freezing conditions. Such processes can lead to protein denaturation and disruption of the cell membrane. To prevent protein denaturation, so-called cryoprotectors can be incorporated into the meat prior to freezing.
A relatively new freezing technology, known as “pressure-shift freezing”, has been introduced as a potential meat quality preservation method. During pressure-shift freezing process, meat samples are chilled to subfreezing temperatures, and will not freeze under a certain high pressure. When the pressure is suddenly released, instantaneous and homogenous microcrystallization occurs throughout the muscle tissue. Meat processed with pressure-shift freezing reportedly has a minimally altered ultrastructure, reduced protein denaturation, and an improved product quality.

How long it’s safe to keep meat in the freezer

According to the United States Department of Agriculture, because freezing keeps food safe almost indefinitely, recommended storage times are for quality only.
However some nutritionists recommend to keep meat in the freezer up to 1 year, as long as it was frozen while still fresh, and has been solidly frozen the entire time.
The packaging of the meat has a great influence on the freezing quality as, for instance, vacuum-packed meat will last longer and have little to no freezer burn.
For best quality, meats shall be kept in the freezer as follows:

Item	Months
Bacon and Sausage	1 to 2
Gravy, meat or poultry	2 to 3
Ham, Hotdogs and Lunchmeat	1 to 2
Meat, uncooked roasts	4 to 12
Meat, uncooked steaks or chops	4 to 12
Meat, uncooked ground	3 to 4
Meat, cooked	2 to 3
Poultry, uncooked whole	12
Poultry, uncooked parts	9
Poultry, uncooked giblets	3 to 4
Poultry cooked	4
Wild game, uncooked	8 to 12

Source: http://www.fsis.usda.gov/Fact_Sheets/Focus_On_Freezing/index.asp

Check after twawing

Notwithstanding the above, the best way to determine whether a frozen meat is still good for consumption is to determine its quality after thawing.
First of all use your nose and smell it. Some meats will develop a rancid or off odor when frozen too long. If that happens they should be discarded immediately. Other may not look perfect or be of high quality to serve alone but may still be edible; in the latter case you can still make soups or stews with them.

Considerations

Bottom line is that meat stored constantly at 0 °F will always be safe. Only the quality suffers with lengthy freezer storage. Freezing keeps food safe by slowing the movement of molecules, causing microbes to enter a dormant stage. Freezing preserves food for extended periods because it prevents the growth of microorganisms that cause both food spoilage and foodborne illness.
It goes without saying, fresh is always better than frozen, but since we can’t always have it fresh, knowing how to deal with frozen meat is an important step towards better health.

The Iron You