Antioxidant and antimicrobial properties of combination bilberry (Vaccinium myrtillus L.) and propolis as beverage

This study developed a novel functional beverage by enriching a bilberry drink with propolis extracts and evaluating its physicochemical, antioxidant, antimicrobial and phenolic properties. Color parameters (L*, a*, b*, C*, H°) varied depending on the type of propolis extract and extraction method. Soluble solid content ranged from 10.90 to 11.03°Bx, pH from 2.72 to 2.98, and titratable acidity from 0.26 to 0.34 g malic acid/100 mL. Total phenolic content (462.80–948.58 mg GAE/L), total flavonoids (440.72–1365.07 mg QE/L), and FRAP values (19.55–59.48 µmol TE/mL) indicated strong antioxidant potential. DPPH and ABTS assays showed antioxidant activity between 7.99–16.43 µmol TE/mL and 3.10–5.37 µmol TE/mL, respectively. Total monomeric anthocyanins ranged from 56.31–71.40 mg/L, while HMF levels were 8.57 to 19.54 mg/L. Sugar content varied across samples, with total sugars between 7.96–20.22 g/100 mL. Phenolic analysis identified compounds such as gallic, chlorogenic, caffeic, p-coumaric, and ferulic acids, along with flavonoids like naringin, myricetin, quercetin, and naringenin, and resveratrol. GC-MS results showed that furan compounds were the dominant chemical class. Overall, propolis enrichment enhanced phenolic content, antioxidant capacity, and functional value, suggesting strong potential as a healthier beverage alternative.