Inactivation kinetics of horseradish peroxidase in organic solvents of different hydrophobicity at different water contents |
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Authors: | Jorge Saraiva Jorge C Oliveira Susana Oliveira & Marc Hendrickx |
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Affiliation: | Escola Superior de Biotecnologia, Universidade Católica Portuguesa, R. Dr. António Bernardino de Almeida, 4200 Porto, Portugal,;Centre for Food Science and Technology, Faculty of Agriculture and Applied Biological Sciences, Katholieke Universiteit Leuven, Kardinaal Mercierlaan 92, B3001 Heverlee, Belgium |
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Abstract: | The thermal stability of horseradish peroxidase suspensions was studied in three organic solvents of different hydrophobicity (dodecane, octane, and 1-octanol) at three different water contents (14.1, 55.3 and 256.2mg water g−1 dry protein). In these conditions, the enzyme is much more stable than in aqueous solutions (inactivation temperatures were in the range of 125–150°C). The enzyme showed a similar stability when in the presence of organic solvents, compared to the enzyme in a solid matrix without organic solvents with the same water content. The inactivation kinetics was well described by assuming the existence of two iso-enzymes, both inactivating according to a First order model. The lowest value for the z-value of both fractions (around 15°C) was obtained at the higher water content studied. The use of solvent and water content variables should be adequate to develop time-temperature integrators to monitor thermal processes at 100–140°C. |
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Keywords: | Biocatalysis enzyme thermal inactivation time-temperature integrators water activity |
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