Liquefaction Process Optimization in the Enzymatic Hydrolysis of Starch Materials

An Industrial level we found process that generate subproducts or waste, these not being treated properly can cause various environmental problems, they are usually burned or dumped in landfills, eleasing carbon dioxide, pollution of waterways and other negatives (Barragan et al., 2008).

Some of these residues are starchy, such as cassava, wheat, molasses, potato, banana, corn (Poonam & Ashok, 2011), which present potential food for obtaining glucose syrups. These residues are constituted by starch and this is formed by amylose, formed by glucoses glucoses linked by glycosidic bonds α-1,4 and amylopectin, consisting of glucoses linked by glycosidic bonds α-1,6 (Curvelo-Santana et al., 2010). Obtaining glucose is carried out by a three step process: gelatinization, liquefaction and saccharification. Gelatinization where grains are heated with water to generate the breaking of the starch and release amylose and amylopectin. Liquefaction carried out by amylases enzymes that hydrolyze the links α- (1-4) starch producing dextrins, maltose, maltotriose and maltopentoses. Saccharification, where glucoamylase enzyme (amyloglucosidase), hydrolyzes liks α- (1-4) y α- (1-6) (Wild & Strain 2011). Both enzymes are susceptible to inhibition by substrate, product, enzyme concentrations, temperature and pH. For this reason, the identification and optimization of reaction conditions affecting enzyme activity could improve the economic and technological viability of bioprocess (Wild & Strain 2011).

In this work, the optimization of conditions for liquefaction processes for two raw material are performed, starting with the characterization of raw material, measuring enzyme activity for SPEZYME®FRED of Genencor, according NREL protocols. Two central compounds designs and response surface analysis were performed, for two variables, temperature and enzyme / substrate ratio, ranging from 75°C-80°C and 0,02% - 0,11%, respectively for pure wheat starch, and 70°C - 80°C and 0,04% - 0,11%, respectively for mixture starch, fixed the pH in 5.8 and the processing time in 1hour for 13 experiments, finally statistical significance was determined from analysis ANOVA and R² of the design, and found the conditions that maximize the concentration of reducing sugars, temperature of 74.1°C and enzyme substrate ratio of 0.0276%, for wheat starch, for an expected value of 57,6g / L with a confidence interval of 95 % between 52,51g / L - 64.27 g / L, for which validation was 61.89 g / L, and a temperature of 72.8°C and enzyme substrate ratio of 0.0516%, for mixture starch, for an expected value of 64,83g/L with a confidence interval of 95 % between 59.13 g / L - 70,53g / L, for which validation was 59,42g /L, with the respective R² = 94.16% and R² = 84,84%.

Bibliography

Barragán.H.B.E Tellez.D.Y.A Laguna. T. A., 2008. Use of agro-industrial waste. Laboratory Hazardous Waste. Department of Environmental Systems Engineering. National School of Biological Sciences. Av. Wilfrido Massieu S / N, Professional Unit Adolfo López Mateos. Mexico DF.

Curvelo Santana,J., Ehrhardt, D., Tambourgi, E., 2010. Otimização da produção de álcool de mandioca Optimizing of alcohol production from manioc starch. , 30(3), pp.613â??617.

Poonam, S. N. Ashok P.2011. Biotechnology for Agro-Industrial Residues Utilization. University of Ulser. Faculty of life & Health. United Kingdom.

Wild, C. & Strain, Y., 2011. Enzymatic Hydrolysis of Cassava Starch for Production of Bioethanol with a Colombian Wild Yeast Strain. , 22(12), pp.2337â??2343.