Phenolic extracts from bilberry (Vaccinium myrtillus L.) residues as new functional food ingredients

Bilberry residues were investigated as a potential source of phenolic antioxidants. Polyphenol extraction was carried out in a mechanically stirred device at 40 °C and 300 rpm using aqueous ethanol (60% v/v) used as solvent. The polyphenol content of the resulting extract was 81.69 ± 6.12 mg GAE/g dw and the antioxidant activity was 7.58 ± 0.27 mmol TE/g dw. Bilberry extracts were incorporated in varying amounts into a natural drinking yogurt and a condensed milk. Depending on the added amount of extract, the antioxidant activity of the fortified drinking yogurt ranged from 1.69 to 3.27 μmol TE/mL and that of the condensed milk from 12.16 to 23.16 μmol TE/g. The results obtained demonstrate that bilberry residues can be used as a valuable source of phenolic antioxidants and support the possibility of using the phenolic extracts to produce new functional food products with high antioxidant capacity. Using an agro-industrial waste as a source of polyphenols could contribute to reduce its environmental impact and provide economic benefits to the producers.