Crossword Clue:

to make sour or bitter

AnswerCrossword Clue
ASTRINGENTSour or bitter in taste
TASTESweet, sour, bitter, or salty
ACERBSour or bitter in taste
UMAMITaste that's not sweet, sour, salty or bitter
UMAMITaste that's not sweet, sour, bitter or salty
ALOESomething bitter to make one better