The content of bioactive substances and their antioxidant effects in the European blueberry ( Vaccinium myrtillus L.) influenced by different ways of their processing

Abstract

The objective of this study was to evaluate the effect of traditional processing methods on the polyphenol, flavonoid, phenolic acids, anthocyanin contents, and the antioxidant activity of European blueberry (Vaccinium myrtillus L.). All methods had a significant effect on the investigated bioactive substances. The total polyphenol content was 39,562–44,760 (fresh), 12,495–20,266 (dried), 7504–9472 (frozen), and 3029–5876 (sterilized) mg GAE/kg DW. Processing resulted in a reduction in flavonoid content on average by 86.8 (drying), 75.8 (sterilization), and 50.2% (freezing). The anthocyanins content ranged from 7419–9719 (fresh) to 560–649 mg Cye/kg DW (dried). Due to processing, the antioxidant activity decreased in the order of dried > frozen > fresh > sterilized (DPPH) and dried > fresh > frozen > sterilized (FRAP). The obtained results confirmed a reduction in the content of biologically valuable substances and antioxidant activity in blueberries after processing, but their complete degradation did not occur. Novelty impact statement The present study provides more comprehensive information regarding valuable biological compounds in blueberries and their changes due to processing methods for their preservation. Investigated preservation methods (freezing, sterilization, and drying) did not cause a significant reduction of phenolic compounds. Therefore, even processed blueberries can be considered a valuable source of health-promoting substances.