Use joined table's data

I'm trying to access my joined table data but alas..

For example association between authors and books, author have many books: I'm using join funtion to join the author table to the books table in order to access the author's author_name attribute

class Author < ActiveRecord::Base
  has_many :books

  attr_accessible :author_name
end

class Book < ActiveRecord::Base
  belongs_to :author
end

random_author = Author.first
books = random_author.books.where(id > 5).joins(:author) #this should make all author attributes available to each book, right?

book_1 = books.first
book_1.author_name
=> NoMethodError: undefined method `author_name' for #<Book:0x111111>

Of course using the association would work: book_1.author.author_name but that will require another query, which is what I'm trying to avoid.

I mean the joins operation joins the author's data- there must be a way to access it right?

p.s. I can use includes method. and eager load the author data as well, but since I'm just needing a single attribute- is there a way to accomplished it with only a joins method? Thank you