In your application in actual state, you are mapping the field Classifications of table Menu with Food_name of mapping table. This never will match.
If you want to use a mapping table for food:
You should use:
item_id, Food_name FROM
First field is the field to map, and second is the result.
And then ApplyMap('Temp',item_id) as item_substitute (Here item_id is the field of Menu table.