Antioxidant properties of coffee substitutes rich in polyphenols and minerals

Abstract

The analysis of general content of polyphenols, minerals and antioxidant activity of infusions from selected coffee substitutes is presented. The obtained results showed that the coffee infusions prepared from acorns exhibit the highest radical scavenging capacities for DPPH (EC₅₀ = 0.063-0.066 mg_d.w./mL), ABTS (EC₅₀ = 0.021-0.029 mg_d.w./mL), OH(EC₅₀ = 2.050-2.378 mg_d.w./mL) as well as the highest ability to Fe³⁺ reduction (FRAP) (∼1.1 mmolFe/g_d.w). These coffee substitutes also contain the greatest values of polyphenols (45-50 mgGA/g_d.w). Analyzed coffee substitutes differ in both quality and quantity of polyphenols, but all tested coffees contain gallic and chlorogenic acids. The most of phenolic compounds was found in herbal-cereal coffee substitute. The quantitative results and PCA analysis indicated a good correlation between the antioxidant activity and total polyphenols, flavonoids and gallic acid content. Using the obtained data on the composition and antioxidant properties of extracts the cluster analysis (CA) was performed to distinguish similar or close types of coffee.

Keywords: Antioxidant; Coffee substitutes; Minerals; Polyphenols.