Changes in pH of Coffee Extract depending on Temperature and its Quality

Abstract

Three kinds of coffee beans (Colombia, Santos, and Madagascar) roasted to four roasting stages respectively, were brewed by the cup-test procedure, and pH values were measured immediatly. The pH value of any kind of coffee fell to minimum at light roast, but began to rise at a subsequent roasting stage. The degree of this falling pH increased by order of Madagascar, Santos, and Colombia. Along the lowering temperature from 70°C to 26°C, the pH fell within ranges of 0.04-0.26. Santos indicated relatively susceptible effect of temperature on the otherhand, Colombia indicated moderate effect, and Madagascar, indicated little effect. It was suggested that these results correlated to organoleptic quality of coffee used in this experiment.