Fuid additives are substances addit tae fuid tae preserve flavor or enhance its taste an appearance. Some additives hae been uised for centuries; for example, preservin fuid bi picklin (wi vinegar), sautin, as wi bacon, preservin sweets or uisin sulfur dioxide as in some wines. Wi the advent o processed fuids in the seicont hauf o the 20t century, mony mair additives hae been introduced, o baith naitural an airtifeecial origin.