Restrict specific fields in the response of rails controller

I have a controller action like

def index
  @videos =  Video.all.to_a

  respond_to do |format|
    format.xml  { render :xml => @videos }
    format.json { render :json => @videos }
  end
end

Video has attributes name and title.

I want the return xml to contain only title.

How do I restrict it from the response.