A better process is to introduce buttermilk cultures to whole or skimmed milk, it is then homogenized and pasteurized. This is not real buttermilk, it is a product resembling buttermilk. Natural buttermilk is dried and then sold to pancake companies to be used in pancake mixes. The reason for this being that it will produce a better flavor than artificial buttermilk. Pasteurized and homogenized.
Product thickens while bacteria multiply.
Flavorings and stabilizers are added before the product is packaged. Do not count on the upper limit . It will depend entirely on the producing creamery where they want to be with their percentage. As long as they do not fall below or rise above the acceptable standard, they are within the law. There are differences between producers and products.