Tuesday, January 12, 2010


This might be a topic that you don't want to discuss this time of year but I say its perfect! Over the holiday my father gave me a prime Top Sirloin Butt weighing about 14 lbs. I was planning on cutting it up, making nice steaks so I threw it in a small cooler and put it outside the back door. That night the wind blew like crazy and the temperature plummeted. The next day I went skiing in the Catskills and forgot all about the Sirloin. The temperature barely got to the teens. One more frigid night and the beef was solid! So did I ruin a perfectly good prime steak cut? Well today's post will focus on the effects of freezing meats and how and when to do it correctly.

Meat is at least 70% water so freezing it creates ice crystals. If meats are frozen slowly ice crystals grow large and break through the muscle cell struture and and damage the delicate sheaths that bundle muscle cells. This damage results in moisture loss upon thawing. When meats are frozen rapidly such as blast freezing using fans and temperatures well below zero, much smaller ice crystals are created. This results in much less damage to the cell structure. When you buy a frozen duck or turkey it was most likely blast frozen so the quality level will be higher than if you froze a fresh bird slowly in a normal freezer. Thats not to say you should never freeze, just do it carefully. I will spread out products to ensure a rapid freeze instead of freezing in a large lump.

Other effects of freezing are changes in flavor. The environment of a freezer is much like that of a high peak mountain, very cold, windy and really really dry. This dryness can result in freezer burn. Freezer burn is non-pathenogenic but destroys flavor quality. The burn occurs when meat is exposed to the air of the freezer creating a leathery layer on the outside, resulting in toughness and a stale, off taste. Freezer burn can be trimmed away. To prevent it, be sure to keep meats in air-tight packaging.

Although the act of freezing stops the growth of many pathogenic organisms it does not sterilize meat. Salmonella, campylobacter, yeasts, molds and other organizms can "hibernate" during freezing so when meats are thawed they are reactivated. Also bacterial toxins can be present even if the bacteria themselves are destroyed. Meats that are starting to spoil should not be frozen to protect them.

Certain fats, especially those in pork, duck and goose can go rancid even while in the freezer. Fats become oxidized and the flavor changes dramatically. Prolonged freezing even in air tight packaging can result in self oxidizing fat. Rendered fats are not effected as much and can be stored much longer.

What about the effects of freezing on nutritional values? The protein and fat values stay the same but some more delicate vitamins are reduced by freezing. Thiamin and vitamin C are both greatly dimished by freezing.

Freezing is a part of meat purchasing today and many foodservice operations depend on it. So what can we do to minimize its downsides? At the CIA we try to freeze rapidly as cold as possible. We vacuum package most meats and we try not to freeze longer than needed. In other words we use the freezer as a purchasing tool as opposed to a long term storage shed. Six months should be the maximum for most meats and even less for fragile high cost meats.

The other part of this conversation is thawing. The best way to thaw is slowly in the walkin. Rapid thawing at room temp can result in rapid bacterial growth. Thawing in a sink with cool running water is OK but it is wasteful and if there is any leakage in packaging the meat product is waterlogged and ruined. Thawing in a microwave is a possibility but can result in partial uneven cooking if done incorrectly and also wastes energy.

By the way, the temperature rose to 32F today so I put the Sirloin in the freezer. I'll pull it out just in time for Memorial Day weekend and no later!