Sensory profiling of Robusta and Liberica coffee leaves functional tea by modifying brewing temperature

Abstract

Traditionally, the coffee leaves, particularly the mature, is mostly used as compost or cattle feed. The leaves have also been traditionally processed as herbal tea in which popular in West Sumatera as Kahwa tea. This current study aims to characterise the sensory profile of Robusta and Liberica coffee leaves tea using Rate All That Apply (RATA) method. Not only profiling, but optimising the sensory acceptance of the coffee leaves tea is also required. The sensory optimisation was conducted by applying Just about Right (JAR) method. Both RATA and JAR evaluation were involving 110 consumer respondents. All coffee leaves tea was brewed by decoction technique ranging from 85 - 100°C. There are 7 out of 27 sensory attributes which were significantly affected by brewing temperature. These are sweet flavour, burnt flavour, earthy flavour, woody flavour, sweet and bitter taste, and astringent mouth-feel. Penalty analysis of JAR data shows that sweet taste, bitter taste and astringent mouth-feel of Robusta coffee leaves were optimum at 95°C. Meanwhile Liberica coffee leaves tea was optimum at 85°C for most attributes except woody flavour. To some extent, the changes of sweet, bitter taste and astringent mouth-feel attributes are correlated to caffeine and total phenolic compound.