What is the ruling on eating a cake that was sent to the family, and then it was discovered that it contained a trace amount of alcohol not exceeding 0.1g/100?

It is not permissible to eat sweets if intoxicating alcohol has been added to them while it remains in its original state, as it renders them impure. However, if the added alcohol has transformed into another non-intoxicating substance before being added to the sweets, there is no objection to eating them.