Calorimetric studies on dry pectinlyase preparations: impact of glass transition on inactivation kinetics |
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Authors: | Taragano V M Pilosof A M |
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Institution: | Departamento de Industrias, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, 1428 Buenos Aires, Argentina. |
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Abstract: | The glass transition temperature (T(g)) of a dry ultrafiltrated pectinlyase (PL) preparation decreased from 56 to 24 degrees C when water content increased to 20%. The thermal transition temperature (T(p)) for protein denaturation decreased greatly up to 40% moisture; above 40% no further changes in T(p) were observed. In the glassy state, a lag period of approximately 7 days with no PL activity loss was observed; after that, PL activity was lost. Above T(g), the rates of PL inactivation greatly increased. In the glassy state E(a) was 16.6 kJ/mol. When the system was in a higher mobility state (rubbery), E(a) increased to 66.5 kJ/mol. |
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