2.3.3. Condensed Tannin Content

The CTC in HI extracts was assessed according to a modified version of the vanillin assay formerly described [18]. In a 96-well plate, 50 μL of HI sample was added to 250 μL 0.5% vanillin in 4% concentrated HCl in methanol. After the plate was incubated in the dark at 30 ◦C for 20 min, the absorbance was measured at 500 nm against a solvent blank. The CTC was expressed as catechin equivalents (CE) per dw of involucre (mg CE/g dw).
