You can search for food images and use them in your blogs, portfolios and posters. However you need to be aware of the Creative Commons logo and its variants. Creative Commons indicates that the resource is copyright free however there are exceptions and you need to check what each logo indicates. Scroll to the bottom of advanced search and search only for copy right free open source images.
"Creative Commons is a non-profit that offers an alternative to full copyright."creativecommons.org
You let others copy, distribute, display, and perform your copyrighted work - and derivative works based upon it - but only if they give you credit.
You let others copy, distribute, display, and perform your work - and derivative works based upon it - but for noncommercial purposes only.
No Derivative Works means:
You let others copy, distribute, display, and perform only verbatim copies of your work, not derivative works based upon it.
Share Alike means:
You allow others to distribute derivative works only under a license identical to the license that governs your work.