EFFECT OF FERMENTATIO TIME ON CAFFEINE CONTENT, PHENOLIC COMPOUND, AND FLAVOUR OF ROBUSTA COFFEE (Coffea canephora)

• Main Author: Tadzkiroh, Amah
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/41369
• Institution: Institut Teknologi Bandung

Indonesia is the fourth largest coffee exporter in the world and the second largest in South East Asia. Robusta coffee is widely produced in Indonesia with total production of 473,672 tons or about 73.57% of total coffee production of the country. The caffeine content of robusta coffee is 1.5-2.5% and chlorogenic acid 7-14%, therefore it generally has more bitter taste profile and tends to be more acidic compared to Arabica coffee. This is one of the reason of why robusta coffee has a low preferences. On the other hand, the high content of the two compounds also caused Robusta coffee to have very high antioxidant activity, as evidenced by IC 50 values ranging from 10-50 ppm. However, the coffee processing carried out by farmers is different in each region, resulting in different quality of the coffee produced. In addition, the fermentation of the cherry still not able to procude good quality coffee. Therefore, it is necessary to do a second fermentation on Robusta coffee to improve the quality of the coffee. One of the quality improvements can be seen from the changes in taste produced during fermentation. Coffee taste is influenced by the content of precursor compounds such as carbohydrates and proteins. The carbohydrates content of cellulose and pectin groups in Robusta coffee reaches 8% and 2% respectively, while the protein content in Robusta coffee reaches 10-13%. Components of these compounds can be broken down by cellulolytic, proteolytics, and pectinolytics enzymes which are possessed by microbes throught fermentation technology. This study aims to determine the effects of fermentation using cellulolytic, pectinolytic, and proteolytic bacteria on bacterial population dynamics during fermentation, caffeine content, total content of phenol compounds, antioxidant activity in Robusta green bean, and profile analysis of steeping Robusta roasted coffee. Analysis of caffeine content was carried out using the Liquid-Liquid Extraction method Analysis of the total phenol compounds content was carried out with Folin Ciocalteu Reagent method. Analysis of antioxidant activity was carried out by the DPPH method. Proximate analysis was analyzed by reffering to the method determined by AOAC (2005). Analysis of amino acids profiles was carried out by the UPLC method (Gressler, 2010), while the profile analysis of fatty acids was carried out bu the GC method. The taste analysis was carried out bu the cupping test method with certified panelist at 57-58 Coffee Labs by following the procedures established by the SCAA. Analysis of pH of Robusta coffee steeping was done with a pH meter. while sweetness level analysis is analyzed by refractometer. Based on the results of the analysis, fermentation can reduce caffeine concentration from 1.93% in unfermented Robusta green bean to 1.01% in Robusta green bean fermented for 12 hours. The highest caffeine degredation rate was found in green bean with 12 hours fermentation treatment with a value of 0,0752% caffeine/hour. Total content of phenolic compounds of Robusta green bean coffee increased from 5,2% in unfermented green bean to 6,8% in robusta green bean fermented for 12 hours. The highest rate of phenol compounds addition was found in the 4 hours fermentation treatments with a value of 0,215%/hour. The antioxidant activity of Robusta green bean decreased during fermentation as shown by the increase in IC 50 value from 28.9 ppm in unfermented bean to 38 ppm in bean fermented for 12 hours. The highest increase in IC 50 rate was found in 4 hours of fermentation treatment with a value of 1.858 ppm/hour. The higher IC 50 value indicates a decrease in antioxidant activity. Fermentation decreases the taste test value (cupping test), the value of cupping test on unfermented Robusta coffee is 79, while on ferme: nted robusta coffee for 4, 8, and 12 hours respectively is 76; 77.75; and 78.25. However, the fermentation for 4, 8, and 12 hours was able to increase the variation of the taste of the Robusta coffee which was different from the unfermented Robusta coffee. The sweetness and pH value of coffee increased during fermentation with the highest value was found in coffee fermented for 12 hours with sweetness value reaching 0,73% Brix and pH value 4.82. Based on the results of the research, fermentation technology has the potential to increase the variety of flavors of robusta coffee.