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Enzyme Immobilization on Biopolymer Carrier by Microencapsulation Technique

Hemmati, Mostafa | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47707 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Aalemzadeh, Iran; Vossoughi, Manouchehr
  7. Abstract:
  8. β-galactosidase enzyme is immobilized from Kluyveromyces lactis by Microencapsulation method in various compositions of sodium alginate and Carboxymethyl cellulose. Optimum stabilization was gained at 1.85% sodium alginate, 0.9% carboxymethyl cellulose and 2% calcium chloride through applying Surface response methodology. Yield of immobilization and activity was 54.94% and 65.27%. variation of yield of immobilization versus alginate concentration was a quadratic curve with the maximum. When alginate's concentrations is low, the cavities diameter is great, so the enzyme leaks from capsule while immobilizing. At high concentrations of alginate, despite the smaller cavities, immobilization reduces. This happens since the increase of solution viscosity affects enzyme molecular dispersion. Variation of yield of immobilization versus carboxymethyl cellulose concentration was a quadratic curve with the maximum. Carboxymethyl cellulose is highly water retentive and it prevents enzyme leak while immobilization. In high concentration, the capsule lose its spherical shape and leak was observed. Yield of immobilization changes versus calcium chloride concentration does not follow a specific pattern. Immobilized lactase enzyme activity linearly decrease, increase and decrease in order by the concentration of alginate, carboxymethyl cellulose and calcium chloride. An increase in alginate concentration will decrease the cavities diameter, hence substrate availability will decrease, but an increase in carboxymethyl cellulose will increase media porosity. An increase in calcium chloride concentration changes the pH from 6.1 to 4. The enzyme's maximum activity in free mode is at 45°C and pH=6.5 and 45°C and pH=7 in immobilized mode. Immobilization results in thermal stability. Immobilized enzyme can hydrolyze 57% milk lactose on fourth round of reuse. Thermal stability study of immobilized enzyme at room temperature and 6°C shows that Immobilized enzyme must be kept in refrigerator
  9. Keywords:
  10. Lactase Enzyme ; Sodium Alginate ; Carboxymethyl Cellulose ; Microencapsulation ; Biopolymer

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