According to several reports, the twist ties and plastic tags on loaves of bread are meant to indicate when the loaf was baked.
In fact, there’s an entire color code, Reader’s Digest reported.
According to the website, each color represents a different day that the bread was baked: blue tags indicate the bread was baked on Monday, green tags indicate Tuesday, red tags indicate Thursday, white tags indicate Friday and yellow tags indicate Saturday.
Reader’s Digest reported that most commercial bakeries are closed on Sunday and Wednesday, which is why those days don’t have specific colors.
According to Insider, the reason bakeries color-code their twist ties and tags is to help employees find stale loaves and replace them with fresh loaves.
For that reason, it is unlikely you’ll ever see more than two colors on shelves, according to Reader’s Digest.
Though this system isn’t necessarily universal -- some local bakeries might have their own systems -- it is "widely used at commercial bread bakeries across the country," Reader’s Digest reported.