Smelly Kitchen Drain

We do not have a garbage disposal and even though we scrape plates before hand washing, some food pieces slip down the drain.  I feel the kitchen always had a faint but weird smell.  I always thought it was the trash or something else. Last night, I decided that it could be the drain.  Who knows if they cleaned the drain before we moved in or if the past tenants ever attempted it, but it needed to be done.  We have a double sink so I poured a half a cup of baking soda in each and forced it down with the back of a utensil.  Then I poured a half a cup of white vinegar in each drain and let it fizz.  Followed by a pot of boiling water on each side.  It has not smelled yet and hopefully it stays that way.