Impact of Applying Magnetic Fields on the Development of Postbiotic Metabolites and Probiotic Microorganisms in Kombucha Tea.

The rising interest in fermented beverages is attributable to their content of probiotics and postbiotics. Kombucha, a fermented tea, captivates consumer interest. A natural source of probiotic bacteria and a variety of postbiotics, Kombucha is produced using a complex culture of different bacteria and yeasts (SCOBY). This study examined the physicochemical, microbiological, and textural changes of kombucha teas produced using SCOBY cultures subjected to varying magnetic field strengths (180 mT, 240 mT, and 300 mT) and durations (1, 2 h). The impact of magnetic field applications on the existence of probiotic bacteria and the generation of postbiotic metabolites in the samples was also examined. The total count of bacteria in SCOBY increased synchronously with the intensity and duration of the magnetic field. The highest spp. bacteria and acetic acid bacteria and osmophilic yeast counts were determined in sample M2.2 with 4.08, 5.25, and 5.31 log cfu/mL, respectively, and the highest total yeast/mold count was determined in sample M3.2 with 5.15 log cfu/mL. The weight of the pellicle increased simultaneously with the increasing quantity of microorganisms. The maximum pellicle weight was recorded in the M2.2 sample at 101.91 g. The organic acid concentrations in the samples increased in parallel with the increase in microbial population. The maximum concentrations of acetic acid, D-glucuronic acid, gluconic acid, lactic acid, and citric acid were 6.30, 1.65, 3.28, 0.38, and 0.054 mg/100 mL in the M2.2 sample, respectively. Furthermore, applying the magnetic field at the end of fermentation resulted in elevated levels of total phenolic compounds and enhanced antioxidant capacity. The significance of magnetic field applications in improving the health and nutritional attributes of fermented beverages like Kombucha tea, which have gained consumer preference in recent years, by augmenting D-glucuronic acid and postbiotic metabolites has been unequivocally established.