Quality characteristics of in vitro luwak coffee produced using enzyme and microbial complexes

Abstract

In vitro luwak coffee was produced using enzyme-microbial complexes. The coffee quality of non-fermented coffee beans (NFC) and fermented coffee beans (FC) was compared. The total free amino acid content was higher in FC than in NFC. The levels of glutamic acid and γ-amino-n-butyric acid in NFC were higher than those in FC; however, the contents of essential amino acids, such as lysine, leucine, and valine, in FC were higher than in NFC. During fermentation, the sucrose content decreased, whereas the fructose and glucose contents increased (p<0.001). The chromaticity of the coffee extract showed higher lightness (L), redness (a), and yellowness (b) values in FC than those in NFC. The caffeine content was significantly lower in FC (696.94±0.04 μg/mL) compared to that in NFC (1,130.22±1.55 μg/mL) (p<0.001). Conversely, the polyphenol and chlorogenic acid contents were significantly higher ​​in NFC than in FC (p<0.001). Electronic nose analysis indicated considerable differences between the volatile aromatic components in NFC and FC. Sensory scores were significantly higher for FC than those for NFC. Therefore, the fermentation of coffee beans using enzyme-microbial complexes altered the chemical components, which promoted the Maillard reaction during the coffee bean roasting process. These results suggest the possibility of producing in vitro luwak coffee with better flavor and lower caffeine content.