Determining the impact of roasting degree, coffee to water ratio and brewing method on the sensory characteristics of cold brew Ugandan coffee

Abstract

In today's market, there is a growing demand for high-quality coffee with distinctive sensory characteristics, such a cold brew (CB) coffee. The objectives of this study were to determine the impact of a) degree of roasting, b) coffee to water ratio (C2WR), and c) brewing method on the sensory characteristics of CB coffee from d) various Ugandan coffee beans, both Robusta and Arabica. Four distinct coffee samples, sourced from lowland and mountainous regions in Uganda, were roasted and tested using a factorial design. A highly trained sensory panel evaluated the samples using 42 attributes. Results showed that all factors studied had an impact on most of the attributes. Not surprisingly, Robusta coffees generally had more bitter taste than Arabica coffees and the dark roast samples generally were more bitter than the medium roast coffees. Also, coffee samples that were brewed using a higher C2WR generally were more bitter than the coffees using a lower C2WR. However, although most of the main effects had a significant impact, their effects were mitigated by their interaction with other factors. For example, Medium roast Robusta that was slow-dripped with a high C2WR had a more bitter taste than the corresponding Arabica samples. However, when the Medium roast Robusta was steeped with a high C2WR it had a similar bitter intensity with the corresponding Arabica samples. Thus, although major impacts are critical, individual sample combinations must be considered when evaluating coffee samples for their impact on the sensory characteristics.

Keywords: Arabica; Coffee; Cold brew; Flavor; Roast; Robusta; Sensory; Taste; Uganda; Water ratio.