Display Attributes on Invoice or Packing Slip in Magento

Add this to Mage/Sales/Model/Order/Pdf/Items/Invoice/Default.php, $product->getIngredients(),  replace  as appropriate. 

$product = Mage::getModel('catalog/product')->load($item->getProductId());
         $lines[1][] = array(
         'text' => Mage::helper('core')->__('Ingredients: ') . $product->getIngredients(),
         'feed' => 35
   );