Bitter: it’s the flavor we equate with being, well, the opposite of flavor. The puckering not-quite-sour bite of bitterness in foods is what we tell our children is an acquired taste they’ll “grow to love.” But the truth is, many people don’t ever develop a fondness for bitter; they prefer instead the sweetness of sugar or the savory depth of salt and umami. Well, a new book aims to change all that.