Characterization of -Amylase and Protease from Indigenous Lactobacillus fermentum EN17-2 and Its Use in Tuber Paste Flour

a-Amylase and protease are biocatalyst which can be used in paste flour to produce natural sweet paste flour. Production of these enzyme in Indonesia are limited, so, to increase those enzyme production, alpha-amylase and protease from indigenous bacteria are needed. This research focused in characterization of alpha-amylase and protease from indigenous Lactobacillus fermentum EN17-2 and its use in tuber paste flour. Crude enzymes of alpha-amylase and protease were characterized. Tuber sources were cassava (Manihot esculenta) and sweet potato (Ipomoea batatas) with wheat (Triticum) as comparison. alpha-Amylase activity and reduction sugar were detected by DNS methods, while protease was detected by tyrosin method and protein degradation was detected by titration. The results show that optimum activity of alpha-amylase from L. fermentum EN17-2 was reached at pH 5.5, 45 degrees C, while that optimum activity of protease was at pH 6.5, 35 degrees C. Stability of a-amylase from L. fermentum EN17-2 was at pH 5.0-6.5, 30-60 degrees C; while that protease was at pH 4.5-8.0, 20- 50 degrees C. The reduction sugar content of cassava and sweet potato paste flour were 13.50% and 23.70%, respectively, while that the reduction sugar content of those flour added a-amylase from L. fermentum EN17-2 were 32.54% and 24.30%. The protein degradation of those paste flour were 0.49% and 1.17%, respectively, while that the protein degradation of those flour added protease were 1.90 % and 1.68%. The increase of reduction sugar in those paste flour were 58.51% and 2.47%, while that protein degradation were 1.40% and 0.50%, respectively. Based on the increase of reduction sugar and protein degradation in those treated paste flour, it concluded that the characterized a-amylase and protease from L. fermentum EN17-2 was better to be used as biocatalyst in cassava pasta flour to produce natural sweet paste flour than that sweet potato.