Modulation of the antioxidant activity of a functional oat beverage by enrichment with chokeberry juice

Modern functional food companies are focused on the development of products offering multiple health benefits through combining various functional ingredients. Following this trend, the aim of the present study was to enrich a probiotic oat beverage with antioxidants by the addition of chokeberry juice. It was necessary to assess how different quantities of chokeberry juice affected the antioxidant activity of the oat beverage and the fermentation potential of the starter monoculture of Lactobacillus plantarum Pro in the liquid oat matrix. Results show that the starter culture was well tolerant to chokeberry juice of up to 20% added before fermentation. Also, fermentation of the oat matrix with aronia juice was proved to increase the total antioxidant activity of the product compared to the addition of aronia juice after fermentation. The sensory evaluation of four beverage variants confirmed that supplementation with chokeberry juice improves the sensory acceptance of a fermented oat beverage. Novelty impact statement The study explored the possibility to extend the functionality of a probiotic oat beverage by supplementation with chokeberry juice. The addition of up to 20% chokeberry juice did not inhibit the growth of the probiotic starter culture and its fermentation activity. The addition of chokeberry juice before fermentation resulted in higher antioxidant activity of the beverage compared to the addition after fermentation, and sensory evaluation of four beverage variants confirmed that supplementation with chokeberry juice improves the sensory acceptance of the fermented oat beverage.