Can I add a custom link to "Main Menu" via hook_menu?
The correct code would be the following one; notice the commented line.

function custom_food_orders_menu() {
  $items['order_food'] = array(
    'title' =&gt; 'Order Food',
    'page callback' =&gt; 'page_creator_function',
    'access callback' =&gt; TRUE,
    'menu_name' =&gt; 'main-menu',  // This is the changed line.
    'type' =&gt; MENU_NORMAL_ITEM,
  );

  return $items;
}


There aren't properties returned from hook_menu() (and generally from any hook used from Drupal core code) that uses the equal character.