Several factors can affect the color of a raw steak ... called oxymyoglobin and turns from darker purple to a brighter blood-red hue. It's why meat often looks dark when it's vacuum-packed ...

Examples are Kool-Aid or Jell-O. The only colors we worry about are red, black (not dark green) and white. "Bloody stools": 90% of red stools are not caused by blood Blood from lower GI tract ...