Phenolic Composition Stability and Antioxidant Activity of Sour Cherry Liqueurs.

The aim of the study was to evaluate changes of phenolic and anthocyanin contents, antioxidant activity, aroma compounds and color of sour cherry liqueurs with and without sugar during 6 months of storage at temperatures of 15 °C and 30 °C. Contents of phenolic compounds (HPLC, UPLC-MS) and antiradical activity (ABTS) changes were measured. Color changes were measured by an objective method (ColorQuest XE). During storage fluctuations of phenolic compounds and antioxidant activity content were observed. The content of substances which react with Folin-Ciocalteu reagent was comparable before and after 24 weeks. During the 24 weeks of storage, the highest average antioxidant activity against ABTS radicals was shown by sour cherry liqueurs without sugar, stored at 15 °C. Quicker degradation of anthocyanins was observed in liqueurs without sugar, stored at 30 °C (t(1/2)-5.9 weeks in liqueurs with sugar and 6.6 weeks in liqueurs without sugar). Better stability of red color was observed in liqueurs with sugar, stored at 15 °C. The content of the dominant aroma compound, benzaldehyde, increased during storage. Long-term storage and sugar addition decreases color attributes but increases organoleptic value without of great influence on antioxidant activity. Studies on a half-year period of liqueur storage showed that their characteristic features are almost unchanged if stored at 15 °C and without sugar added, but organoleptic properties were better in samples stored at 30 °C.