Changes in glucosinolates and their breakdown products during the fermentation of cabbage and prolonged storage of sauerkraut: Focus on sauerkraut juice

• Glucosinolates (GLS) degraded after 4 days of fermentation. • 17 GLS breakdown products were determined in sauerkraut products. • The loss of individual breakdown products varied during fermentation and storage. • Ascorbigen was the dominant breakdown product of GLS in sauerkraut and juice. • Sauerkraut juice is a rich source of bioactive breakdown products of GLS. Sauerkraut juice has not gained much scientific attention to date. Therefore, this study aimed to track changes in glucosinolates (GLS) during fermentation of white cabbage and the formation of corresponding breakdown products in sauerkraut and sauerkraut juice separately and to evaluate their stability during prolonged storage of the final products. The results obtained indicate that both sauerkraut and sauerkraut juice are a good source of bioactive compounds: ascorbigen and isothiocyanates. The stability of individual compounds during storage varied, and the absolute content of phytochemicals depended on the content of native GLS in the raw material and its bacterial composition. The dominant compound was ascorbigen, stable in acidic pH in both sauerkraut and sauerkraut juice, even after prolonged storage. Sauerkraut juice was also found as a rich source of bioactive isothiocyanates. One 250 mL glass of sauerkraut juice (after two weeks) can deliver approx. 75 μmol of bioactive ascorbien and isothiocyanates, hence it can be considered as functional food, delivering beneficial health effects.