Fe3+-polyphenol dark complexes

Ingredients

Quebrantar Ground galls, Water, White wine vinegar, Azeche (FeSO4), Gum arabic

Preparation Steps

Original Recipe Text

The Braga recipe (Table 1, p. 3) uses Quebrantar Ground galls in a solvent mixture of water and white wine vinegar in a 2:1 ratio (15.90 mL per 1 g of galls). The iron sulfate source is 'Azeche'. The mass ratio for Galls:FeSO4:Gum is 1:4:0.5. The preparation requires boiling the mixture until the volume is reduced twice. This recipe does not include a filtration step. Preparation followed medieval treatises from the 15th-17th centuries (p. 9).

Evidence

"Five representative Iberian recipes were selected and prepared. Their phenolic profile was analysed by HPLC–DAD and HPLC–ESI–MS... Braga | Quebrantar Ground | Water:Vinegar 2:1 | Azeche | 1:4:0.5 | Boil, reduce 2x"

Remarks

The Braga recipe uses white wine vinegar as one third of the total solvent volume (p. 6, 8). Among the recipes, it used the highest amount of FeSO4 (p. 4). HPLC analysis showed that the addition of gum arabic induced variations in the concentration of phenolic compounds only in this recipe (p. 4). The pH of the final ink was significantly low (1.39-1.41), which is a major driver of paper degradation (p. 8). Phenolic compounds present in higher concentration in the gall extracts were pentagalloylglucose and hexagalloylglucose (p. 1).