The Collaborative International Dictionary of English v.0.48:

Acetify \A*cet"i*fy\, v. t. [imp. & p. p. Acetified; p. pr. &
   vb. n. Acetifying.] [L. acetum vinegar + -fly.]
   To convert into acid or vinegar.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Acetify \A*cet"i*fy\, v. i.
   To turn acid. --Encyc. Dom. Econ.
   [1913 Webster]

WordNet (r) 3.0 (2006):

acetify
    v 1: make sour or more sour [syn: sour, acidify,
         acidulate, acetify] [ant: dulcify, dulcorate,
         edulcorate, sweeten]
    2: turn acidic; "the solution acetified" [syn: acidify,
       acetify] [ant: alkalify, alkalise, alkalize,
       basify]