Assessment of the bioavailability of flavonoids in herbal beverages with antioxidant properties

Relevance. The development of fermented herbal beverages will make it possible not only to process grain crops as efficiently as possible, but also to meet the needs of people with intolerance to milk components, as well as those who adhere to a vegetarian diet. As one of the directions, it is possible to offer production of fermented vegetable drinks with predetermined properties by enriching them with antioxidants of polyphenolic nature. These technologies will minimise the risks of non-communicable diseases in the Russian Federation and stabilise public health in the long term.Methods. Six samples of fermented herbal beverages were identified as objects of study, two of which were obtained by fermentation of wheat and barley grains using "Bifivit" starter, powdered flavonoid taxifolin was added to other two samples at the fermentation stage, while the last two used the hydroxypropyl-betacyclodextrin encapsulated form of taxifolin. Total flavonoid content using spectrophotometric method, antioxidant activity(AOA) using DPPH-method as well as bioavailability index and digestibility criterion were determined in all tested samples.Results. All the samples of fermented herbal beverages with taxifolin are characterized by sufficiently high flavonoid content. The samples containing encapsulated forms of the flavonoid have, on average, 7 to 8% lower values than the samples of herbal drinks containing the native form of the flavonoid. At the same time, the bioavailability index for the samples containing encapsulated forms of flavonoid was on average 40 to 42% higher, indicating the effectiveness of the encapsulation process. The highest values of antioxidant activity were characteristic of the plant drinks enriched with the initial form of taxifolin, which is probably due to the creation of a protective shell and a decrease in the AOA values by 10–12% on average in samples with encapsulated form. The process of fermentation of vegetable raw materials leads to an increase in their digestibility, as evidenced by the growth of the infusoria Tetrahymena pyriformis. Introduction of taxifolin into the formulation of drinks both in its original and encapsulated form increases the growth of protozoa by 187±4–315±3%. 