Sheikh Sa`d al-Shuwayrikh
I do not know any textual prohibition specifically for blowing over food. The only textual references mention drink.
Blowing over a hot drink is permissible as long as it that person is going to be the only one to drink it, as in case of a cup of tea. The prohibition of blowing over a drink is when others are to drink or to share from. In such cases, the blower would contaminate the drink for others.
Therefore, there is no prohibition on blowing over food or drink intended for the person himself.
Source: Islam Today