Effect of High Pressure and Heat on Bacterial Toxins

• Published in: Food technology and biotechnology Vol. 43; no. 3; pp. 211 - 217
• Main Authors: Margosch, D, Moravek, M, Gaenzle, M G, Maertlbauer, E, Vogel, R F, Ehrmann, M A
• Format: Journal Article
• Language: English
• Published: University of Zagreb Faculty of Food Technology and Biotechnology 01.07.2005
• Subjects: bacterial toxins; food safety; high hydrostatic pressure
• ISSN: 1330-9862; 1334-2606

Even though the inactivation of microorganisms by high pressure treatment is a subject of intense investigations, the effect of high pressure on bacterial toxins has not been studied so far. In this study, the influence of combined pressure/temperature treatment (0.1 to 800 MPa and 5 to 121 degree C) on bacterial enterotoxins was determined. Therefore, heat-stable enterotoxin (STa) of cholera toxin (CT) from Vibrio cholerae, staphylococcal enterotoxins A-E, haemolysin BL (HBL) from Bacillus cereus, and Escherichia coli (STa) were subjected to different treatment schemes. Structural alterations were monitored in enzyme immunoassays (EIAs). Cytotoxicity of the pressure treated supernatant of toxigenic B. cereus DSM 4384 was investigated with Vero cells. High pressure of 200 to 800 MPa at 5 degree C leads to a slight increase of the reactivity of the STa of E. coli. However, reactivity decreased at 800 MPa and 80 degree C to (66 plus or minus 21)% after 30 min and to (44 plus or minus 0.3)% after 128 min. At ambient pressure no decrease in EIA reactivity could be observed after 128 min. Pressurization (0.1 to 800 MPa) of heat stable monomeric staphylococcal toxins at 5 and 20 degree C showed no effect. A combined heat (80 degree C) and pressure (0.1 to 800 MPa) treatment lead to a decrease in the immuno-reactivity to 20% of its maximum. For cholera toxin a significant loss in latex agglutination was observable only at 80 degree C and 800 MPa for holding times higher than 20 min. Interestingly, the immuno-reactivity of B. cereus HBL toxin increased with the increase of pressure (182% at 800 MPa, 30 degree C), and high pressure showed only minor effects on cytotoxicity to Vero cells. Our results indicate that pressurization can increase inactivation observed by heat treatment, and combined treatments may be effective at lower temperatures and/or shorter incubation time.