I've just started using a slow cooker, and have had pretty mediocre results in keeping my meat moist vs. conventional cooking. For example, the chicken always seems overdone and dry. Even my beef stew has been on the dry side, with my latest one almost inedible (not tough--just dry) after 7.5 hours on Low. My question is: Am I simply overcooking it (i.e. the slow cooker might be hotter than the recipes call for)? Should I start adjusting my times down, and if so, by how much? Or is it meant to be stewed longer? Should I add more liquid? The vegetables seem perfect, though.
I've actually used several different models of slow cooker (some borrowed, some bought and returned), and they all seem to dry the meat.-- Ramona
This may come as a surprise, but what is likely happening is that you are overcooking the meat. We tend to think that if you stew meat, the longer it cooks, the more tender and juicy it gets. In fact, this works only up to a point.
As proteins heat up, they loosen their internal bonds, begin to uncoil and bond with neighboring protein molecules. See Custards and Sauces for a description of how proteins change with temperature.
However, at somewhere around 170°F (76°C), depending on the meat used and the other ingredients present, the protein network begins to break apart again and and the individual molecules tighten back up. As that happens, the muscle fibers in the meat shrink, their cell walls break open and the water that was trapped within the muscle fiber starts to leak out. The result is that the texture of the meat becomes dry even though it was cooked in liquid. The same thing can happen in a pot roast or even with meat dishes cooked on the stovetop.
If you're like many people who start supper in the slow cooker before you leave for work in the morning then you are taking part in a balancing act. You are trying to cook the food at a sufficiently high temperature so that it gets out of the danger zone for bacterial growth fairly quickly. That temperature range is between 40°F and 140°F (4°C to 60°C). On the other hand, you don't want to overcook the meat to the point of being too dry. This isn't an easy balance to achieve.
Just to clarify here, based on the comment below from Catt, 140°F (60°C) is the top end of the danger zone through which you want the heat to rise quickly. In order to kill salmonella and other pathogens, you need to cook until the center of the meat is at least 165°F (74°C). While protein starts to tighten around 170°F (76°C), it doesn't become unpleasantly dry until around 185°F (85°C), so between 165°F and 185°F (74°C and 85°C) is the target range, if you are measuring. I would shoot for around 175°F (79°C).
I would try cutting the meat into somewhat larger chunks, perhaps up to about 2 inches (5 cm) to a side, and cooking for a shorter period of time. Once the cooker gets up to temperature, try cooking the food for about 5 hours longer. That should give you a total cooking time of about 6 hours. If the meat is still coming out dry, reduce the time by another half hour or so. For safety, though, always be sure that the meat is cooked completely.
If you want to see more recommendations on using a slow cooker check out the posting Browning Meat for Slow Cooker.