The Changes of Antioxidant Activity of Three Varieties of 'Nalewka', a Traditional Polish Fruit Alcoholic Beverage during Long-Term Storage

The diet rich in fruits is widely recommended for health-promoting properties. Regular consumption of fruits could reduce the risk of many diseases. The fruit-based alcoholic beverages have been produced for centuries and, in many countries, are still very popular. 'Nalewka' is a traditional name of Polish liqueur, i.e., an alcoholic beverage made by maceration of fruits. Homemade nalewkas are often stored for a long time before consumption, which can affect the content of valuable secondary metabolites. The aim of the study was to compare the effect of long-time storage on antioxidant activity and total polyphenol, total anthocyanin, tannin as well as gallic acid content in three homemade nalewkas. Cherry, plum, and multifruit nalewka were produced in 1997 and between 2013-2019 years. The antioxidant activity was measured by the DPPH, ABTS, FRAP, and CUPRAC methods. The content of gallic acid was estimated by high-performance liquid chromatography (HPLC). The oldest nalewkas (from 1997) showed significantly lower antioxidant activity as well as a lower content of polyphenols, anthocyanins, and gallic acid compared to the later-produced nalewkas, in particular those produced in 2016-2019. In most cases, a correlation was also found between the parameters of antioxidant activity as well as the total content of polyphenols and anthocyanins. Long-term storage of nalewkas reduces the content of valuable secondary metabolites responsible for the antioxidant activity and, thus, the health properties of the beverage.