Comparative assessment of two extraction procedures for determination of bioactive compounds in some berries used for daily food consumption

Summary Two extractions with methanol and water were used to determine the antioxidant and binding properties of some berries as a supplement to food. Fluorometry, FTIR spectra and radical scavenging assays were used for characterisation of bioactive compounds (polyphenols, flavonoids, flavanols and tannins) and the levels of their antioxidant activities (AAs). The contents of bioactive compounds and AAs in water and methanol polyphenol extracts in gooseberries, blueberries and cranberries differed, but not always significantly. Water extracts of gooseberries showed the lowest amounts of polyphenols (mg GAE g−1), 6.24 ± 0.6, and flavonoids (mg CE g−1), 0.29 ± 0.01, and AAs (μMTE g−1) determined by DPPH, FRAP, ABTS and CUPRAC assays such as 6.05 ± 0.6, 8.07 ± 0.9, 18.70 ± 1.8 and 13.44 ± 1.2, respectively, in comparison with blueberries and cranberries. Polyphenol content highly correlated with antioxidant activity (R2 from 0.94 to 0.81). The quenching properties of berries were studied by the interaction of water and methanol polyphenol extracts with HSA by 3D fluorescence. In conclusion, the bioactivity of gooseberries was lower than in blueberries and cranberries. Gooseberries can be used as a new source for food consumption and supplementation based on their antioxidant and binding properties. 3D fluorescence spectroscopy and FTIR spectroscopy can be applied as additional analytical tools for rapid estimation of the quality of different food products.