Effect of temperature and time on mold growth, mycotoxin contamination, phytochemicals and microbiological characteristics of kombucha tea during fermentation

The effect of fermentation temperature on mold growth and mycotoxins contamination of kombucha tea was studied. Kombucha was prepared under home-made conditions. The samples were collected within 14 days during fermentation carried out at 17, 22, and 25°C and controlled for the presence of mold (by microbiological cultures) and mycotoxins: patulin, ochratoxin A, penicilinic acid, aflatoxins B 1 , B 2 , G 1 , G 2 , and M 1 (by chromatographic measurements). To assess the quality of fermented tea, levels of phytochemicals and microorganisms were also monitored. The higher fermentation temperature was shown to support the growth of Aspergillus species even at the early stages of kombucha fermentation. At 17°C, aflatoxin M 1 and penicilinic acid were more prevalent (77% positive samples), but patulin was detected in one beverage sample. This was probably the result of both contamination of initial substrates used for fermentation (e.g. starter) and a lower amount of microorganisms capable of mycotoxins biodegradation. The prevalence of mycotoxins (penicilinic acid and aflatoxin M 1 ) in kombucha beverage prepared at 22 and 25°C was 20 and 4.6%, respectively. For these temperatures, the risk of contamination of kombucha with aflatoxin M 1 increased with the fermentation time, suggesting its production by mold. Aflatoxins B 1 , B 2 , G 1 , and G 2 , and ochratoxin A were not detected in kombucha samples (n=64). Furthermore, fermentation temperature affects the quantitative content of the different groups of microorganisms, total phenolic content, and pH of the beverage. The results underline the need for temperature control to obtain kombucha that is safe to consume. • Kombucha fermented at 17°C contained aflatoxin M 1 and penicilinic acid. • Patulin was detected in only one sample. • Aspergillus species were detected in ferments prepared at 22 and 25°C. • Kombucha fermentation at 25°C for 7-10 days is recommended.