Optimized Dextran-Degrading Enzyme Conditions

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The elimination of various molecular weights of contaminated dextran in sugar processing is quite complicated, especially using enzymatic decomposition. Many factors including enzyme concentration, retention time, pH, temperature, and sucrose concentration affect enzyme hydrolysis. The optimizing conditions of various molecular weights of dextran removal were investigated using response surface methodology. The optimum hydrolyzed conditions of 1,500 µg/mL of all molecular weights of pure dextran from the one-factor-at-a-time (OFAT) experiments were: dextranase (Amano Enzyme Inc., Japan) at 5-15 ppm total soluble solids for 5-15 min at 50-65°C with pH 4.5-6.5 and sucrose concentration at 15-25%. The results from the OFAT experiments used a Box-Benhken experimental design with four factors and three levels that achieved fit models that predicted the dextran removal under different conditions of various molecular weights of pure dextran. The low molecular weight of pure dextran (LMW) makes it a less complex structure with smaller molecules and it is easily degraded; therefore, it showed the highest percentage of dextran removal under a wide range of conditions of dextran decomposition than the higher molecular forms consisting of medium molecular weight (MMW) and high molecular weight (HMW) under the same conditions as shown using contour plots. The complete hydrolysis conditions that were calculated from the predicted models all of molecular weights of pure dextran were pH 5.5 and sucrose concentration 15-15.2% with slightly different temperatures of 53.2, 52.4, and 51.5°C and dextranase concentration at 12.4, 13.1, and 14.8 ppm total soluble solids for LMW, MMW, and HMW, respectively.

All of the factors (enzyme concentration, retention time, pH, temperature, and sucrose concentration) affected enzyme hydrolysis, especially the dextranase concentration, temperature, and sucrose concentration which were significant factors for dextran hydrolysis all of molecular weights of pure dextran. The optimum hydrolysis conditions with 1,500 µg/mL for all pure dextran samples from the OFAT experiments were: 5-15 ppm total soluble solids of dextranase, 5-15 min at 50-65°C, pH 4.5-6.5 and less than 30% sucrose concentration. Dextranase could degrade the high molecular weight of dextran into smaller molecules; as a result, the low molecular weight of pure dextran (LMW) with its less complex structure or smaller molecules was easily degraded and therefore, had a higher percentage of dextran removal and a wider range of factors for dextran hydrolysis than did the higher molecules of MMW and HMW under the same conditions. The complete hydrolysis conditions that were calculated from the predicted models for all molecular weights of pure dextran were: pH 5.5 and sucrose concentration 15-15.2% with slightly different temperatures of 53.2, 52.4, and 51.5°C and dextranase concentration of 12.4, 13.1, and 14.8 ppm total soluble solids for LMW, MMW, and HMW, respectively. The fit models could predict dextran removal under the different conditions of various molecular weights of pure dextran. In practice, the elimination of dextran contamination in sugar processing is quite complicated due to contamination with various molecular weights of dextran in the processing stream.

Kind Regards,
Nicola B
Editorial Manager
Journal of Biochemistry & Biotechnology
Email: biochembiotech@scholarlypub.com