Assessment of polyphenol content and antioxidant activity of oak bark extracts

Extraction efficiency of total polyphenols and flavonoids from bark oak (Quercus robur L.) grown in the central region of Poland was evaluated. The total phenolics of water and 60% ethanol and extracts were in the range of 55.4-60.4 and 71.0-79.3 mg gallic acid/g of bark, respectively, while the total flavonoid content in these extracts were determined in the range of 35.1-38.0 and 72.0-78.4 mg catechin/g. The hydroalcoholic extracts exhibited higher DPPH radical scavenging activity than BHT (butylated hydroxytoluene), popular food additives.