Evaluation of radish ( Raphanus sativus L.) peroxidase activity after high-pressure treatment with carbon dioxide

• Published in: The Journal of supercritical fluids 2006-10, Vol.38 (3), p.347-353
• Main Authors: Fricks, Alini T., Souza, Dayse P.B., Oestreicher, Enrique Guillermo, Antunes, Octavio A.C., Girardi, Jonathan S., Oliveira, Débora, Dariva, Cláudio
• Format: Article
• Language: English
• Subjects: Compressed CO 2; Peroxidase; Radish; Specific activity; Water content
• ISSN: 0896-8446; 1872-8162
• DOI: 10.1016/j.supflu.2005.11.019

The objective of this work was to assess the influence of compressed CO 2 on the specific activity of peroxidase (POD) from radish ( Raphanus sativus L.). The protein concentrate, in phosphate buffer, was obtained through the precipitation of proteins with (NH 4) 2SO 4. The peroxidase activity was determined using guaiacol as substrate. A semi-factorial experimental design was adopted to evaluate the effects of temperature (30–50 °C), exposure time (1–6 h), carbon dioxide density ( ρ R = 0.6–1.8, resulting in pressures from 70.5 to 254.4 bar), and depressurization rate (10–200 kg/m 3/min) on the peroxidase activity. Samples of lyophilized proteic concentrate were also submitted to high pressure and the effect of water content on the enzymatic activity in compressed CO 2 was studied. The water content in lyophilized samples was determined by thermo-gravimetric analysis. The results showed that the treatment of the enzymatic concentrate with CO 2 at high pressure could be a promising route to increase the POD activity.