Create Managed Property for Approval Status Coulmn

Approval Status is a SharePoint Inbuilt Column.

Internal Name : ows_ModerationStatus

Value : Integer
            0 = Approved

            1 = Rejected

            2 = Pending

            3 = Draft

• Go to Your Search Service Application > Search Schema
• In Search Schema Select Crawled Properties
• In the Search box type "ModerationStatus" and Search. You will get a crawled Property "OWS_ModerationStatus"
• Create a Managed Property and Map it with this crawled Property.
• 
  
• Do the Full Crawl