Synthesis Of Fructose Stearate Using Eggshell Immobilized Lipase From Rhizomucor miehei
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Date
2017-08
Authors
Mohamed Salleh, Nur Suhaila
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Journal ISSN
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Publisher
Universiti Sains Malaysia
Abstract
One way of the green approach applied in enzyme technology is immobilizing lipase on waste materials as a carrier. Many benefits were obtained when immobilized lipase was used compared to free lipase such as better stability in term of properties and recyclability. One of the main concern in the carrier selection as the carrier material must be economical and abundantly available which eventually will help to reduce the cost of operation. Chicken eggshells were chosen as carrier in this study. Process parameters affecting immobilization process was studied and optimize using Design Expert software. The optimum condition suggested were 1hour immobilization time, 36°C, and 0.4 mL of lipase loading. In synthesis of fructose stearate, 82.3% of fructose conversion was obtained when immobilized lipase was used. Next, parameters affecting synthesis of fructose stearate was studied and optimized using Design Expert software. Synthesizing at optimum condition showed the fructose conversion of 92.5% (50 RPM, 3.3 mmol stearic acid and 3.5 mmol fructose). Synthesis of fructose stearate using immobilized lipase from R. miehei have obeyed ordered bi bi kinetic mechanism. The kinetic constants for free lipase were Vmax= 1.56 mmol L-1 min-1 mL-1 enzyme, KM,acid = 1.35 mmol L-1 min-1 mL-1 enzyme, KM,fructose= 36.72 mmol L-1 min-1 mL-1 enzyme and Ki = 0.42 mmol L-1 min-1 mL-1 enzyme. On the other hand, kinetic constant for immobilized lipase were Vmax= 7.06 mmol L-1 min-1 mL-1 enzyme, KM,acid = 0.023 mmol L-1 min-1 mL-1 enzyme, KM,fructose= 38.05 mmol L-1 min-1 mL-1 enzyme and Ki = 0.026 mmol L-1 min-1 mL-1 enzyme. Thermodynamic studies to compare thermal stability of free and immobilized lipase from R. miehei showed that immobilized lipase is proven to be more thermally stable compared to free lipase according to thermodynamic constant value obtained. Thermodynamic parameters value for free lipase at 30°C were kd = 0.0070 min-1, ΔH° = 5.19 kJ/mol, ΔG° = -230.58 kJ/mol, ΔS°= 0.78 kJ/mol. K and t1/2 = 98.86 min. On the other hand, thermodynamic parameters value for immobilized lipase were kd = 0.0031 min-1, ΔH° = 14.21 kJ/mol, ΔG° = -99.18 kJ/mol, ΔS°= 0.37 kJ/mol. K and t1/2 = 224.78 min. Based on the value obtained, it indicates that immobilized lipase was more thermostable compared to free lipase.
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Keywords
Synthesis of fructose stearate using , eggshell immobilized lipase from Rhizomucor miehei