Effect of water hardness on coffee composition and coffee preference by university students

Water is a major ingredient and comprises over 98% content of coffee. In this study, coffees prepared with distilled water (L) and waters with medium (M) and high hardness (H) were investigated for organic acid, caffeine, and eugenol contents and analyzed by sensory evaluation. Organic acid content was the highest in H-coffee. The contents of chlorogenic acid and caffeine, the characteristic bitter taste molecules, were the highest in L-coffee. The level of eugenol, one of the representative aroma components, was the lowest in M-coffee but similar between L- A nd H-coffees. The sensory evaluation test, conducted on a university student group comprising 56 female and 47 male participants, showed that L-coffee was the most preferred (42% or higher), but there was no significant difference in bitterness, acidity, body, and balance. Results suggest that the preference index of coffee taste among university students may be different from that of coffee experts who prefer coffee extracted with water of certain hardness.