Chemical characterization and bioactive properties of a coffee-like beverage prepared from Quercus cerris kernels

Abstract

In the present study, a coffee-like beverage was prepared from Quercus cerris seeds. Seeds presented 60.4% carbohydrates (of which 26.9% is fiber), 6.3% proteins and 4.0% fat. In the coffee-like beverage, the TPC and TFC were 2070.2 mg GAE per L and 285.3 mg CEQ per L, respectively. The IC₅₀ values determined using FRAP and DPPH assays were, respectively, 203.1 mg L⁻¹ and 271.6 mg L⁻¹. Concerning the reactive species scavenging capacity, the extract was more effective against O₂˙⁻, HClO and ˙NO (namely, IC₅₀ = 17.24 ± 0.24 μg mL⁻¹, IC₅₀ = 9.25 ± 0.92 μg mL⁻¹ and IC₅₀ = 0.65 ± 0.06 μg mL⁻¹). Qualitative and quantitative analyses by 1D- and 2D-NMR and LC-MS indicated high levels of ellagic acid and gallotannin or ellagitannin derivatives. The optimal range of non-cytotoxic concentrations in Caco-2 and HT29-MTX cell lines was between 0.1 and 1.0 μg mL⁻¹. This is the first study that evaluates the Q. cerris seed extract as a beverage.