How long pork roast in refrigerator?

Answer 1

about 2 - 3 hours per pound, typically.

It mostly depends on your method of thawing the roast, and the size of the roast.

The roast if it is about 5 pounds will need to absorb about 720 btus of heat to fully thaw. Let's assume the surface area of the roast is roughly 1 square foot.

Thawing it in the refrigerator at 45 degrees F the air will transfer to the roast ~14.4 btu/hr per degree F/sq. foot. Assuming there is no insulation value (u factor) in the meat itself. 45 -32 (temperature of ice) = 13 x 14.4 = ~187 btu/hr
720/187 =~4 hours, HOWEVER, meat does have an insulating value, unlike a melting block of ice, which would thaw similar to this. This insulating value of the meat slows the thawing of the meat in a steadily increasing rate such that it takes longer to thaw the center than the outer edges. This changing rate of thaw for solid masses other than ice blocks means it takes as much as four times longer to thaw a large piece of meat than smaller pieces. Taking the above assumption then a five pound roast will actually, because of this changing rate of heat absorption (why the outer edge of meat can be fully cooked and the center frozen), take about 8 to 12 hours to thaw in a refrigerator.

Thawing it in a basin submerged in water, because the rate of heat exchange is 4 times faster than the rate of exchange with air, will be 4 times faster. Roughly 2 to 3 hours for a five lb. roast.

Thus when thawing a 20 lb. turkey for Thanksgiving, it takes about 2-3 days in the refrigerator but only overnight (12-15 hours) when thawed in a water filled tub.

Attempting to thaw a roast while cooking it is not really recommended. It might reduce the thawing time but the outer shell of the roast will overcook, dryout or burn. If doing this cook the roast an extra 10-15 minutes per pound and reduce the cooking temperature by 100 degrees F for the first third of the cooking time.
Braising, [cooking in a covered roasting pan on a rack with a braising liquid in the roasting pan], is often a good method to use here to avoid drying out the roast.