3.3.2. Total Flavonoid Content

Flavonoids exhibit both in vitro and in vivo biological activities and may elicit health benefits including cardiovascular protection [35]. In this study, the highest value for the TFC was 43.10 ± 1.59 mg QE/g dw involucre (N6, run order 7, Table 3). As in the case of phenolics, the best values for total flavonoids were obtained at equal volumes of water and acetone in the solvent mixture.

To the best of our knowledge, there is no research regarding the flavonoid content in HI, therefore TFC values for nuts and other by-products were used as a comparison. The highest flavonoid content in walnut septum was 9.76 ± 0.23 mg QE/g [15], while hazelnuts presented TFC values between 0.09 ± 0.01 and 0.36 ± 0.07 mg rutin equivalent/g extract [36].
