The study of Vaccinium uliginosum L. fruit anthocyanins quantitative composition and antioxidant activity

Object and methods: quantitative analysis of anthocyanins in bog bilberry (Vaccinium uliginosum L.) fruits and evaluation of antioxidant activity. Antioxidant activity was assessed by ABTS, CuPRAC, DPPH, FRAP, TFPH spectrophotometric methods. Aim: to investigate quantitative composition and its variance of anthocyanins and proanthocyanidins in fruits, fruit pomace and juice of bog bilberry (Vaccinium uliginosum L.) handpicked in natural populations in Lithuania and assess antioxidant activity of extracts. Objective: to optimize extraction of anthocyanins from bog bilberry fruits. Evaluate quantitative composition of anthocyanins and proanthocyanidins in bog bilberry fruits, fruit pomace and juice and its dynamic changes during fruit ripening. Evaluate anthocyanins and proanthocyanidins quantitative composition and its variation in fruit samples, fruit pomace and juice of bog bilberry handpicked in different locations. Determine antioxidant activity of bog bilberry fruit, fruit pomace and juice ethanol extracts. Evaluate correlation between quantity of anthocyanins and proanthocyanidins and antioxidant activity. Results: optimal extraction conditions of anthocyanins from bog bilberry fruits – modified maceration extraction method in ultrasonic bath for 15 minutes at room temperature as an extrahent using 60 % (v/v) ethanol, acidified with 0,1 % hydrochloric acid. Optimal raw material and extrahent ratio 1:10. The highest amount of anthocyanins in bog bilberry fruits (0,219±0,016 %), fruit pomace (0,245±0,026 %) and juice (0,198±0,031 %) were determined at the end of fruit ripening on August 22nd. The highest amount of proanthocyanidins in fruit (0,0316±0,0027%), fruit pomace (0,0234±0,0029%) and juice (0,0373±0,0052 %) were determined in samples handpicked at the same time. The highest amount of anthocyanins and proanthocyanidins in bog bilberry fruits, fruit pomace and juice were determined in samples handpicked in Lekėčiai, Slavinčiškės and Darynė forests (anthocyanins 0,206-0,275 %, proanthocyanidins 0,0319-0,0439 % accordingly). The highest antioxidant activity (TEAC, mmol/g) in fruit, fruit pomace and juice was assessed with CuPRAC method (215,21±3,90 mmol/g, 237,49±0,71 mmol/g, 205,33±2,71 mmol/g accordingly). The strongest correlation between anthocyanin content and antioxidant activity (TEAC, mmol/g) was estimated at 0,951-0,980 using CuPRAC method