Optimisation of the antioxidant activity of kombucha fermented milk products

Abstract

The antioxidant activity of fermented milk products obtained by using kombucha starter produced by fermentation on sweetened wild thyme extract was investigated. The starter was added to milk containing 0.8, 1.6, and 2.8% milk fat, at fermentation temperature of 37, 40, and 43°C. The fermentation process was terminated when the pH reached 4.5. Antioxidant activities to DPPH and hydroxyl radicals, the contents of MUFAs, PUFAs, vitamin C, and sensory mark, were monitored using the response surface methodology (RSM) and the method of desired function. Kombucha fermented milk products containing wild thyme (WT) showed opposite antioxidant response to DPPH and hydroxyl radicals in terms of milk fat. Optimum processing conditions for WT products in terms of antioxidant activity were: milk fat 2.78% and process temperature 37°C. In order to obtain WT products with a high sensory mark, these conditions are completely different (milk fat 1.10% and process temperature 43°C).