Optimization of robusta green coffee fermentation using response surface methodology

Abstract

Kombucha coffee is a fermented coffee bean, which is extracted using a combination of bacteria and yeast. Kombucha coffee can be obtained by optimizing the three variables, namely sugar concentration, incubation temperature and duration of fermentation using a response surface methodology (RSM). This study aimed to produce kombucha coffee with a low concentration of caffeine and a high concentration of chlorogenic acid by optimizing three influential variables in the fermentation. The analysis of caffeine and chlorogenic acid contained in the kombucha coffee was carried out by using High Performance Liquid Chromatography (HPLC) and then the analysis of optimization was carried out by using Response Surface Methodology (RSM). The results of RSM show that the optimum condition was obtained at sugar concentration of 6.77% (b/v), incubation temperature of 25 °C and incubation for 18 days. The results were similar to HPLC analysis. Finally, the fermentation using RSM on kombucha coffee required an additional variable which is the amount of kombucha culture inoculums, as well as the variables of sugar concentration, incubation temperature, and duration of fermentation.