"Tasty novel" is an unlikely phrase without a specific meaning in English parlance. "Juicy novel" does have a specific meaning and would be understood with fair accuracy by most English speakers. Therefore "juicy novel" is the only correct collocation in English.
The phrase, "juicy novel", expresses the idea that the story of the book will or does or may contain any of the following: sensual interest, sensual content, sexual interest, sexual content, secrets, secrecy, romantically oriented action, gossip, or otherwise prurient content.
Though "juicy" does not equate to "sexual", the connotations of juicy are certainly associated with the ideas of passion and interest, especially where these two concepts intersect.