The Collaborative International Dictionary of English v.0.48:

Gustable \Gust"a*ble\, a. [See Gust, v.] [Obs.]
   1. Capable of being tasted; tastable.
      [1913 Webster]

            This position informs us of a vulgar error, terming
            the gall
            bitter; whereas there is nothing gustable sweeter.
                                                  --Harvey.
      [1913 Webster]

   2. Pleasant to the taste; toothsome; savory.
      [1913 Webster]

            A gustable thing, seen or smelt, excites the
            appetite, and affects the glands and parts of the
            mouth.                                --Derham.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Gustable \Gust"a*ble\, n.
   Anything that can be tasted. [Obs.]
   [1913 Webster]