Copper content in kombucha fermented milk products

Abstract

Copper belongs to a group of essential elements, and needs to be replenished through food in certain quantities every day. But on the other hand, ingestion of large amounts of copper has an adverse effect on the human body, so that food should be subject of control in terms of copper content. In this work the copper content was determined in twelve different samples of kombucha fermented milk products using potentiometric stripping analysis, which was preceded by the determination of optimum conditions for carrying out the analysis. Fermentation liquid used as inoculum for the fermentation of milk is obtained by cultivation of kombucha on cooled tea. Four different kinds of tea were used for preparing tea: winter savory, peppermint, stinging nettle or wild thyme. Thus, four different kinds of fermentation liquids were obtained. The technique of potentiometric stripping analysis is applied with the dissolved oxygen as an oxidant, and the mercury film electrode as a working electrode. The copper content in samples was calculated using standard addition method. The contents of copper in the analysed kombucha fermented milk products were within the range from 0.016 mg/l to 0.036 mg/l, with a mean value of 0.25 mg/l. On the basis of the results of this study we can conclude that daily consumption of kombucha fermented milk products provides significant amount of copper to the human body in relation to milk, that is necessary for adults and children alike.