Cellulase and protease assisted sugar germination on quality improvement of Robusta coffee in comparison to Arabica coffee

Abstract

Arabica and Robusta coffee are the two main coffee tree species that are cultivated around the world. Premium Arabica coffee is rich in flavour and aroma. Meanwhile, the cheaper Robusta coffee has a bitter taste, a muddy odour, and a weaker aroma and flavour. This study aimed to improve the quality of Robusta coffee through cellulase and protease assisted germination. Germination results in producing flavour precursors and can be accelerated by degrading the endosperm of coffee beans through the activity of cellulase and protease. Quality parameters were based on morphological study (scanning electron microscope [SEM]), flavour profile analysis (gas chromatography-mass spectrometry [GC-MS]) and sensory evaluation. Results indicated that sugar-and enzyme-added germinated Robusta (R5) has similar morphological characteristics and pH values to Arabica. Flavour profile analysis indicated that 2-Furanmethanol of treated Robusta, which contributes to bitter taste, was decreased compared to untreated Robusta (control). In sensory evaluation, the final score of sensory properties of germinated Robusta (R2), enzyme-added Robusta (R3), and sugar-and enzyme-added germinated (R5) was improved, which indicated that there was no significant difference (p>0.05) compared to Arabica. These results showed that the proposed additional processing method of green coffee beans in this study was able to improve the quality of cheaper Robusta coffee which has some similar properties to premium Arabica.