Comment by blackskad

This standard is not unique to Google. It's part of the Schema.org initiative to add semantics to the web. The full definition is here:

http://schema.org/Recipe

The biggest problem with it, imho, is the lack of a proper definition of ingredients. An ingredient is just a plain string containing the unit, amount and name and sometimes an extra note. Having a quadruple instead of a string would make this standard a lot more useful.