ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Death kinetics of Escherichia coli in goat milk and Bacillus licheniformis in cloudberry jam treated by ohmic heating

R. Pereira, J. Martins, C. Mateus, J. A. Teixeira, and A. A. Vicente

Centro de Engenharia Biológica, Universidade do Minho, Campus de Gualtar, 4710 — 057 Braga, Portugal

E-mail: rpereira@deb.uminho.pt

Received: 18 April 2006  Revised: 6 September 2006  Accepted: 15 September 2006

Abstract: The influence of ohmic heating on the death kinetic parameters of Escherichia coli ATCC® 25922 in goat milk and spores of Bacillus licheniformis ATCC® 14580 in cloudberry jam was investigated and compared with that of conventional heating. Ohmic treatment of goat milk shortened the decimal reduction time D in comparison with the D values obtained at conventional treatment. Similarly, the z value, increase of temperature required for a ten-fold reduction of D, was also lower at ohmic treatment. The death kinetics of Bacillus licheniformis ATCC® 14580 spores in cloudberry jam was also studied employing both types of heat treatment. Similar conclusions were obtained for the D values as in the case of goat milk. However, the differences between the z values obtained for ohmic and conventional heating were not significant.

Keywords: ohmic heating - Escherichia coli - Bacillus licheniformis - spores - death kinetics

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-007-0008-5

Chemical Papers 61 (2) 121–126 (2007)