If you don't want certain Yummly actions (Yum and Cooking) posting to your Facebook account you can easily turn them off.

Once you are logged in, select "Taste Preferences" from the dropdown menu below your Yummly member name (in the upper right) of any Yummly page.

When the Taste Preferences window opens up, select "Myself" from the top tabs:

At the bottom of the window, uncheck the Facebook posting options:

Click "Save" and close the Preference window and recipes you "Yum" or "Cook" will not be posted to your Facebook timeline.

Additionally, you can modify the actions within Facebook:

1) In Facebook, access your privacy settings
2) In privacy settings, go to "Apps, Games and Websites"
3) Find Yummly on the list, and click the button "Edit Settings"
4) Within Yummly, remove "This app can post on your behalf."