Response surface optimization of the substance colour indigo production by amylase enzyme

Indigofera leaf production in Indonesia reaches 30 tons of dry matter per hectare per year. Indigo which produce exclusive blue colour already used to dyeing textile, specially "Batik". Batik cloth using natural dyes has artistic value and distinctive colours, as well as ethnic and exclusive impression that have a high value. Indigofera leaves containing blue dye that can be obtained through hydrolysis and oxidation. The hydrolysis reaction using enzyme catalyst. The research objective is to obtain optimum operating conditions of the hydrolysis reaction in the extraction of blue dye with a cellulase enzyme catalyst. Indigofera used leaves 5 month old and tools used include reactors, stirrer, aerator, autoclaves, incubators and ovens. Optimization parameters are studied an α-amylase enzyme concentration of 2.5-10 wt%, pH 5-9 and a reaction time of 4-10 days. The concentration of blue dye was analyzed by gravimetric method. Experimental data were analyzed by the method of Response Surface Methodology and central composite design, the model corresponding linear model with a mathematical equation Y = 6.22763 - 0.02584X₁ - 1.25889X₂ - 0.42239X₃+0.00694X₁²+ 0.08872X₂²+ 0.03747X₃²+ 0.01372X₁X₂ -0.00582X₁X₃ - 0.00208X₂X₃ The optimum operating conditions in the range of studied enzym concentration of 3.1 wt%, pH 7.4 and the hydrolysis reaction time of 5.6 days with a yield dye of 1,42 %.