Low consumption level of Robusta coffee is often due to its high caffeine content. An effort to improve the quality of coffee is through decaffeination using protease is recommended. Tofu waste is potential source of protease, yet there has been no report about decaffeination of Robusta coffee beans (C. robusta Lindl.Ex De Will) by soaking them in the such waste. The aim of this research was to evaluate the effect of types and concentrations of tofu waste as well as the interaction of each type and concentration of industrial tofu waste in terms of caffeine content of the Robusta coffee beans. This study used a completely randomized design factorial i.e. type of tofu waste factor (L0= water, L1= liquid waste and L2= solid waste) and the concentration of tofu waste factor (K1 = 30%, K2 = 60%, and K3 = 90%). Parameter of study observed was level of caffeine of Robusta coffee bean. The results showed that the tofu liquid waste could lower level of caffeine (0.36%) in Robusta coffee better than the solid waste one (0.92%) did. Meanwhile, water solvent (control) could decrease caffeine content of sample by 1.57%. As conclusion, liquid tofu waste at concentration of 90% could significantly improve quality of Robusta coffee by decreasing its caffeine levels.
caffeine, coffee, C. robusta, tofu, waste