<iframe width="580" height="385" src="https://www.youtube.com/embed/azM6QnmtmVo?rel=0&modestbranding=1" frameborder="0" allowfullscreen></iframe> <br>A certain amount of bitterness is actually an essential part of the balance of coffee flavour - just like with chocolate, wine or beer. <br><a href="https://www.youtube.com/watch?v=azM6QnmtmVo">source</a>