Chicken broth is made when using a whole chicken with the meat still attached or a whole chicken that has been cut up with the meat still attached. Since the meat is still attached and will more than likely be used for something else (pot pie, soup, etc.) then the cooking time is generally shorter (45 minutes to an hour). Broth can be used just like stock it just won't have quite as much flavor as stock as it has only simmered for about an hour.
Chicken stock is made using fresh bones from the chicken (no meat). Normally, the backs and necks are used but any bones will make a good stock. I buy whole chickens or split chicken breast and remove the meat (to be cooked later) and use all of the bones from the chicken. Three things that are important to remember when making stock: use COLD water, do NOT bring to a boil, and skim off the fat/impurities during the entire process, and do NOT stir. Chicken stock is simmered for at least 4 hours which makes it richer than chicken broth. You NEVER want to bring stock to a boil. Bringing stock to a boil will make the fat and impurities emulsify into the stock and will never be completed separated. This will make your stock cloudy. Other than the simmering time and bones vs. meat, broth and stock are made the same way.
Dark chicken stock is something I have never heard of until recently. This last year for our anniversary, I got a membership to online cooking courses. It is wonderful. This is where I learned about dark stock. When making dark chicken stock, you caramelize the bones and vegetables before placing them in the cold water to simmer. Also, dark stock is usually simmered anywhere from 6-10 hours. The last difference is that you add a small amount of tomato paste to dark stock. Dark stock is used to add a darker color and deeper flavor to dishes and sauces. You can also make dark chicken broth. Before you start simmering the meat in the water, you would caramelize it in a skillet making sure not to cook the meat all the way through. You would do the same with the veggies. You can caramelize them in the same pan as the meat.
I made white and dark stock this week. There is a HUGE difference in the color and the flavor. I am very excited that I have over 20 cups in my freezer, half white and half dark. I don't know exactly which I will choose for certain recipes. I will have to let you know. I guess it will just depend on the color and flavor that I want and the recipe that I am using. I am going to post the instructions for the white and dark stock today. I hope all of this makes sense! Making stock and freezing it will save you a lot of money!
