Why Should Hamburger Not Be Repeatedly Frozen & Thawed?

After purchase, it is safe to store hamburger meat in a raw or frozen state until use. For a variety of reasons, people may thaw raw hamburger meat, leave it uncooked, then refreeze it. The United States Department of Agriculture cautions against this practice. The agency advises that once people thaw frozen hamburger, they should cook all of it thoroughly within two days rather than refreeze raw meat. While the meat may remain safe for consumption after repeated freezes and thaws, the practice compromises several key qualities of the product.

Bacterial Growth

• Freezing hamburger does not eliminate bacteria. It suspends their activity temporarily, until the meat returns to a temperature higher than 40 degrees Fahrenheit. Once hamburger reaches that temperature, any bacteria present on or in the meat resume multiplying. New bacteria may also contaminate the meat once it is unfrozen, further risking the potential for food-borne illness. Refreezing thawed meat suspends the bacteria again. Though placing the meat back in the freezer is safer than leaving meat uncooked for more than two days, its bacterial content may still increase during the process.

Spoilage

• The primary reason for freezing meat is to prevent it from spoiling. Whether or not hamburger harmful pathogens contaminate the hamburger, it will expire if the consumer does not cook it. Freezing meat preserves it indefinitely, staving off spoilage until it reaches 40 degrees Fahrenheit again. Once the meat's temperature passes 40 degrees Fahrenheit, it resumes aging and gets closer to spoilage. Refreezing hamburger does not reset the clock on the product's age. The USDA recommends cooking beef products no more than two days after thawing them. Refreezing the meat one day after thawing means that it should be cooked one day after it thaws for the second time.

Flavor

• Though hamburger is safe indefinitely as long as it remains frozen, the USDA states that the flavor of the meat starts to diminish after four months in the freezer, even if it remained frozen the entire time. Age, regardless of temperature, deteriorates the hamburger's taste. However, thawing the meat accelerates the deterioration because the state of the water molecules changes from solid to liquid, shifting the proteins in the meat. Freezing and thawing the meat repeatedly accelerates the process further, causing the meat to break down with increasing rapidity.

Texture

• The shifts among the water and protein molecules not only alter hamburger's flavor, they alter its texture as well. Meat frozen and thawed repeatedly becomes increasingly watery and loose. The meat is less likely to remain firm and dense during preparation or cooking. This quality is not only aesthetic. Loose, watery hamburger does not cook as evenly as fresh product and dries faster during the cooking process, leaving diners with a dry, flavorless, crumbly dish rather than the dense, rich and flavorful protein they crave.