acidulant
noun
acid·u·lant
variants or acidulent
ə-ˈsi-jə-lənt 
plural -s
: an acidulating or acidifying agent
vinegar is an acidulant
Word History
Etymology
borrowed from French acidulant, from present participle of aciduler "to make acidic," back-formation from acidulé "treated with acid," borrowed from New Latin acidulātus
First Known Use
1826, in the meaning defined above