Hydrogels to reduce the pH in wines: Effects on phenolic composition and chromatic characteristics

Wine acidity is crucial for stability and sensory properties. Higher pH levels in wines are now common due to factors like global warming. Various acidification methods have been developed to increase acidity, though they may impact wine quality. Thus, the application of two types of hydrogels made with maleic and hyaluronic acids was studied to reduce the pH in wines to desirable values, evaluating the effects of this treatment on phenolic composition and chromatic characteristics of wines by using high performance liquid chromatography coupled to diode array detector and mass spectrometry, and spectrophotometric and sensory analysis respectively. In addition, minerals were determined in wines by atomic emission and absorption spectroscopy to ensure that acidification occurred through ion exchange. These two materials were effective in reducing the pH of wines to desirable values, with the acidification kinetics of maleic acid hydrogels being faster. The reduction of calcium and potassium in acidified wines confirmed the ion exchange mechanism responsible for this acidification, where the carboxyl groups within the hydrogel structure deprotonate releasing protons which are exchange for wine cations. Phenolic composition of wines treated with hydrogels was similar to those of untreated ones and differences were not detected in the sensory color evaluation. These findings provide valuable insights into the use of hydrogels for pH modulation in wines.