Though they are technically the same, you don't want to add either citric acid or ascorbic acid directly into your sausage. Adding either directly will cause the meat to become "mushy", and the meat will not bind. The best way to get that tangy flavor is to use encapsulated citric acid. The capsules break down at 150°F, then release the acid. You can purchase them from most places that sell sausage making supplies. If you have fermento, that is another way to add a tangy taste to your sausage.