As a general rule, best by, best before and best before end dates all relate to quality assurance, suggesting when the food will be at its peak, rather than being indicators of food safety. In the UK, Australia and Canada, expiry and use-by dates relate to food safety, meaning that consuming the food in question after that date has passed may make you ill. In the US, product dating is not required by federal law (apart from on baby formula) and the dates on packaging are not an indicator of product safety. Ultimately, if a food looks or smells bad or has an odd texture or colour, treat it with caution – regardless of the date displayed on the packet.