Found a recipe for spaghetti sauce but only calls for only one 28 oz. can of stewed tomatoes (among other ingredients). I would like to double or even quadruple the amount of sauce so I can freeze it for future use. Original recipe says to cook on high pressure for 10 minutes. By how much should I change the cooking time if I were to double or quadruple the recipe? Original recipe: 1/2 pound each ground beef and italian sausage, 2 cups mushrooms, 1/2 cup onion, 1/2 cup celery, one 28 oz. can of stewed tomatoes and one 6 oz. can of tomato paste plus various dry ingredients.