Make sure to boil for 2 minutes. This takes the raw flour taste out of the gravy. The juices from a beef roast can be frozen until needed. Often I have extra juice and I freeze it in 1 cup containers. It comes in great for making gravy quickly for all kinds of easy weeknight meals for the family. If you do not have any beef juice, you can certainly use beef broth, or use a couple of beef bullion cubes with water to get the beefy flavor. But, by all means, if you have flavorful juices, use them and freeze any left overs. Enjoy.The nutrition value is for 3 cups of the gravy. Divide the amount you plan on using to get the accurate nutritional values.