Buttermilk is the nearly milkfat-free fluid remaining from the butter-making process (i.e., the churning fermented or non-fermented milk and cream) . Buttermilk is also produced by fermentation of fluid skim milk, either by spontaneous souring by the action of lactic acid bacteriaor aroma-forming bacteria, or by inoculation of heated milk with pure bacterial cultures (cultured buttermilk) . Buttermilk may be pasteurized or sterilized.

วัตถุเจือปนอาหารที่ codex อนุญาติให้ใช้ใน buttermilk

Reference

http://www.codexalimentarius.net/gsfaonline/foods/details.html?id=5