The Collaborative International Dictionary of English v.0.48:

Toothsome \Tooth"some\, a.
   Grateful to the taste; palatable. -- Tooth"some*ly, adv. --
   Tooth"some*ness, n.
   [1913 Webster]

         Though less toothsome to me, they were more wholesome
         for me.                                  --Fuller.
   [1913 Webster]

WordNet (r) 3.0 (2006):

toothsomeness
    n 1: extreme appetizingness [syn: delectability,
         deliciousness, lusciousness, toothsomeness]