Ascorbic Acid is now required to be added to any meats in the USA that are cured with the use of nitrites or nitrates.
Nitrosamines occur when you use Nitrites/Nitrates in cured meats, the addition of ascorbic acid reduces this potential during the curing process.
As the ascorbic acid speeds up the curing process it is important not to make up a pre mix and add the acid to the dry cure before you intend to use it. When adding to a sausage mix, add after the cure has been mixed through. If using as a brine, add after the cure has been dissolved.
Please research this subject on the internet as well as reading the below information so that you fully understand Nitrosamines etc.
Used at the rate of 0.3% per kg.
100gms - Ascorbic Acid E300