Physiochemical Properties and Cupping Quality of Gayo Espresso Coffee Based on Blending Ratio and Roasting Techniques

Abstract

Espresso is considered the finest brewing technique to provide coffee's optimum sensory and physiochemical quality. The quality of the Espresso is influenced by many factors, such as bean varieties and origin, roasting process, and blending formation. This research investigated the effect of the blending ratio of two varieties (70:30; 80:20; 90:10 of Arabica and Robusta) of the coffee blend from Gayo Highland Aceh Indonesia, and roasting techniques (conventional and torrefacto) on physiochemical and cupping quality of Gayo espresso. Coffee cupping quality assesses ten coffee sensory attributes based on SCAA cupping test procedures. Physiochemical characteristics refer to pH, total dissolved solids, phenolic contents, and antioxidant activity of Espresso. The research applied a completely factorial randomized design. The research stages were roasting, blending, grinding, and brewing the Espresso. The results showed that both factors blending ratio and roasting techniques, had a significant effect (P≤0.01) on cupping quality (fragrance/aroma, flavor, aftertaste body, overall and balance attributes) and the physiochemical characteristics (pH, total dissolved solids, phenolic contents, and antioxidant activity) of Gayo espresso. The Torrefacto roasting technique, which refers to adding 11% sugar at the end of the roasting process, tends to provide Espresso with better cupping quality, higher pH, total solid particles, and antioxidant activity than the conventional roasting technique. On the other hand, Espresso, which had a blending ratio of 80:20 showed better cupping quality, whereas a blending ratio of 70:30 produced the Espresso with higher total phenol content and antioxidant activity than other ratios.