THESAURUS
souring
acescence, acetification, acidification, acidulation, aggravation, amplification, annoyance, augmentation, contentiousness, deepening, deliberate aggravation, deterioration, embittering, embitterment, enhancement, enlargement, exacerbation, exasperation, fermentation, heightening, increase, intensification, irritation, magnification, provocation, sharpening, worsening