You may get an assignment from your professor that requires you to use peer-reviewed journals. Peer-review is a process of evaluation that an article in a scholarly journal goes through before it is published. Experts, working in the same field as the author, review the article and either accept it, decline it, or return it to the author with suggested revisions before it is published. This process helps to maintain a high level of quality within scholarly journals.
How can you find out if a journal is peer-reviewed? Use Ulrich's Periodicals Directory, which you can find in the A-Z database list from the library's home page. Use the Quick Search box in the upper right-hand corner to search by keyword, subject, or title; or you can browse by various subjects or indexes.
When your search results screen appears, you'll see a legend in the upper right-hand corner:
For example, if you do an exact-title search for Journal of Food Science, you will get the following results:
Note that Journal of Food Science IS a peer-reviewed journal, because it has this image of a referee's shirt to the left of the title: