What is the addition of a vitamin or mineral to a food or beverage in which it was not originally present?

It's a normal procedure since the amount of vitamin or mineral isn't excessive.
Example: 10 mg of vitamin C. But I don't think you'll find vitamins and minerals on a suitable form that allows you to mix in the food or beverage. Only some vitamins can be found as liquids. It's more convenient that you consume supplements of vitamins and minerals as pills or syrup. If you need a particular vitamin or mineral you may need help from a pharmacist.