ACIDULATE
sour, acidify, acidulate, acetify
(verb) make sour or more sour
Source: WordNet® 3.1
Etymology
Verb
acidulate (third-person singular simple present acidulates, present participle acidulating, simple past and past participle acidulated)
(transitive) To make slightly or moderately acid; to acidify.
(transitive) To make sour in a moderate degree; to sour somewhat.
(transitive) To use an acidic catalyst, with the chemical change being emphasised over the importance of the change in pH. Used in the processing of biodiesel co-products.
Source: Wiktionary
A*cid"u*late, v. t. [imp. & p. p. Acidulated; p. pr. & vb. n.
Acidulating.] Etym: [Cf. F. aciduler. See Acidulous.]
Definition: To make sour or acid in a moderate degree; to sour somewhat.
Arbuthnot.
Source: Webster’s Unabridged Dictionary 1913 Edition