The Effect of Ethanol, Catechin Concentration, and pH on Sourness and Bitterness of Wine

Abstract

Eighteen wines, varying in ethanol (8%, 11%, 14% v/v), pH (2.9, 3.2, 3.8), and (+) catechin (100 and 1500 mg/ L) were prepared using a dealcoholized white wine concentrate. In a completely randomized design, sourness and bitterness intensities were rated by 20 subjects. Bitterness intensity was increased by the largest magnitude by raising ethanol concentration, whereas lowering the pH produced the biggest increase in sourness. Increasing ethanol from 8 to 11% v/v or 11 to 14% v/v produced 51% or 41% increases in bitterness, whereas addition of 1400 mg catechin raised bitterness only 28%. as pH was raised from 2.9 to 3.2, bitterness was also significantly enhanced, but a further increase from pH 3.2 to pH 3.8 had no significant impact. Sourness decreased with increasing pH and ethanol had no effect on sourness except at pH 3.2, where the increase in ethanol from 8% to 14% diminished sourness significantly. Catechin addition, while increasing bitterness, did not affect sourness.