Wine, Jamaican jerk dressing, vinegar, soy sauce -- all of these ingredients are synonymous with marinating roasts, as their acidic makeup helps tenderize the meat. On the opposite end of the spectrum lies milk, perhaps the least likely liquid you'd nominate to marinate your roast. However, milk -- which has a lower acid content than the aforementioned marinades -- helps you curb the risk of drying out your meat with excess acid, leaving you with an extremely tender and flavorful roast. It's also one of the few marinades with a proven ability to tenderize meats.

Place your roast in a sealable plastic or glass container and add whole milk. Add about 1/3 cup of milk per 1 pound of roast. For this marinade, the meat doesn't have to be drowned in milk.

Add the herbs and seasonings of your choice. Salt, garlic and pepper are classic choices, and cumin provides a smooth, slightly nutty flavor that goes particularly well with a milk marinade, especially when marinating beef or lamb roasts. Cayenne and paprika lend a spicy edge to pork roast marinades, and you can squeeze in a bit a of lemon to add a little zest to your milk marinade.

Place the sealed container in the refrigerator. Marinate a whole roast for at least four hours. For the best results, allow the meat to marinate overnight. If possible, turn the meat at least once on each side as it marinates to ensure an even soak. Remove the roast from its marinade and blot away any excess milk before cooking your roast. Any liquid on the surface must cook away before your roast can brown, and browning contributes significantly to its flavor.

Your roast should always remain refrigerated during the marinating process. Despite the milk's mild acidity your beef remains just as perishable, and the milk itself can also provide a nourishing environment for bacterial growth. When you're done marinating your beef the marinade should be discarded, and you'll need to wash the container - and any utensils or work surfaces that have come into contact with the milk - with plenty of hot, soapy water.