WHY ARE AMERICAN CHAIN RESTAURANT LOGOS RED?

@joylin and I were talking about Red Lobster, and it got me thinking... Why are so many restaurant logos red????
  1. Red Lobster
    The logo is only partially red, but it still applies
  2. Red Robin
  3. Applebee's
  4. Chilis
  5. Wendy's
  6. In N Out
  7. McDonalds
  8. Jack In The Box
  9. Panda Express
  10. Carl's Jr
  11. Arby's
  12. KFC's
  13. Chick-Fil-A
  14. Pizza Hut
  15. Popeyes
  16. TGI Fridays
  17. Does red make you hungry? Is it just a more appealing/attractive color? Is it arousing? What's the deal here?
  18. And it's not just chain restaurants. It's Campbell's Soup, Kellogg's, Oscar Meyer, Betty Crocker's, Pepperidge Farm, Dole, Sara Lee, Post, and Kraft.