Plastic tags, the ones that keep bread bags airtight, are colour coded. As a general rule, the tag’s colour indicates the day of the week a loaf was baked (see chart below). Notice that the colours are in alphabetical order B, G, R, W, and Y. A blue tag, therefore, indicates a loaf that was baked early in the week, a yellow tag means it was produced on Saturday.
Unfortunately, not all companies implement this specific coding convention – some use their own custom-coloured tags, while others rely on one colour for all of their packaging. And to make things even more complicated, there is no tag for Wednesday. Any way you slice it, bread tag codes are difficult to decipher. More than likely, it's a system designed to help grocery stores manage their stock, rather than inform the consumer.