Do You Cook a Roast Frozen or Thawed?

Roasts are typically larger pieces of beef, veal or pork that are meant to be roasted and then divided into smaller portions. Roasts can be purchased in bulk or on sale, and then placed in the freezer for up to a year. Though it may be tempting to take the roast directly from the freezer and place it in the oven, take the time to safely defrost the meat first.

A cooked, tender pork roast on a cutting board with a butter knife. (Image: anhvabe/iStock/Getty Images)

Effects of Frozen Roast

When you leave a roast in its frozen form, you negatively impact several steps of the cooking process. The first is your overall cooking time. Placing the frozen roast in any cooking device increases the overall time needed for the meat to cook, as the meat must first thaw before it can properly cook through. This fact also impacts how evenly your roast cooks. Since the heat affects the outside layer of the roast first, outer portions of the meat can become dry and overcooked, while the inside remains raw or even still frozen, depending on how long the roast has been cooking and on your cooking method.

Bacteria

Proper cooking relies on a defrosted roast. However, if you defrost your roast incorrectly, you can open up the door for potentially harmful bacteria to develop and multiply. Use a defrosting method that keeps the roast below a temperature of 40 degrees Fahrenheit, or that defrosts the roast faster than bacteria can develop. This leaves three main recommended ways to defrost your roast safely -- in the fridge, with cold water, or in the microwave.

Refrigerator

One of the preferred methods of defrosting a roast is in your refrigerator. This is because the refrigerator provides the most consistent way to control the temperature of the meat. This allows the meat to defrost, but not at a high-enough temperature to encourage bacterial growth. The only downside to this method is that it takes substantially longer to complete -- about 24 hours per every five pounds of meat, according to the U.S. Department of Agriculture.

Cold Water

Cold water is the next preferred method for defrosting your roast. For this method, place the roast in a leak-proof plastic bag. The bag is used to keep bacteria in the air and water from entering the meat, and to prevent the roast from taking on water from the container. Immerse the roast completely in cold tap water. Change the water every 30 minutes. Thawing takes about 30 minutes to an hour per pound of roast.

Microwave

The microwave is the least-preferred method when it comes to a roast. This is because the roast can actually start to cook, depending on the settings of your microwave. The time and temperature varies for your roast to defrost. Read your microwave's directions for how long and at what setting to defrost the roast using the weight of your roast as a guide. When thawing the roast in the microwave, always cook it immediately afterward. Do not place the meat back in the refrigerator once it's been thawed unless you fully cook it first.