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Thermal inactivation of Bacillus cereus spores in infant formula under shear conditions

Thermal inactivation of Bacillus cereus spores in infant formula under shear conditions During production of spray-dried infant formulas, spores of Bacillus cereus have to be inactivated in order to assure product safety. The heating step which aims at the inactivation of bacterial spores can be conducted either before concentration of the product or afterwards. However, spores tend to show increased heat resistance in concentrated products. The aim of this study was therefore to determine the inactivation kinetic parameters for the inactivation of B. cereus spores in concentrated infant formula as well as in non-concentrated infant food. Spores of B. cereus IP5832 were suspended in reconstituted infant formula (10 and 50% total solids) and heat-treated at temperatures from 90 to 110 °C under shearing at $$ \mathop{\gamma}\limits^{\bullet }=500\,{s^{-1 }} $$ . Additionally, experiments at 95 °C were performed in tubes without shearing in phosphate buffer and non-concentrated infant formula. In tubes, the inactivation curves exhibited tailing. When applying heat and shear stress, linear inactivation curves were observed in both the concentrated and the non-concentrated infant formula. The kinetic parameters E a and k ref (ϑ ref = 100 °C) based on the employed Arrhenius model were 201 kJ.mol−1 and 0.011 s−1 and 201 kJ.mol−1 and 0.021 s−1 for the concentrated and the non-concentrated medium, respectively. The D values in the concentrated product at the examined temperatures were twofold higher. The heat sensitivity (z value) of the spores was not altered by concentrating the medium. The data from this study can be used to design or evaluate heating processes for concentrated products aiming at the inactivation of B. cereus spores. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Dairy Science & Technology Springer Journals

Thermal inactivation of Bacillus cereus spores in infant formula under shear conditions

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Publisher
Springer Journals
Copyright
Copyright © 2013 by INRA and Springer-Verlag France
Subject
Chemistry; Food Science; Agriculture; Microbiology
ISSN
1958-5586
eISSN
1958-5594
DOI
10.1007/s13594-012-0101-6
Publisher site
See Article on Publisher Site

Abstract

During production of spray-dried infant formulas, spores of Bacillus cereus have to be inactivated in order to assure product safety. The heating step which aims at the inactivation of bacterial spores can be conducted either before concentration of the product or afterwards. However, spores tend to show increased heat resistance in concentrated products. The aim of this study was therefore to determine the inactivation kinetic parameters for the inactivation of B. cereus spores in concentrated infant formula as well as in non-concentrated infant food. Spores of B. cereus IP5832 were suspended in reconstituted infant formula (10 and 50% total solids) and heat-treated at temperatures from 90 to 110 °C under shearing at $$ \mathop{\gamma}\limits^{\bullet }=500\,{s^{-1 }} $$ . Additionally, experiments at 95 °C were performed in tubes without shearing in phosphate buffer and non-concentrated infant formula. In tubes, the inactivation curves exhibited tailing. When applying heat and shear stress, linear inactivation curves were observed in both the concentrated and the non-concentrated infant formula. The kinetic parameters E a and k ref (ϑ ref = 100 °C) based on the employed Arrhenius model were 201 kJ.mol−1 and 0.011 s−1 and 201 kJ.mol−1 and 0.021 s−1 for the concentrated and the non-concentrated medium, respectively. The D values in the concentrated product at the examined temperatures were twofold higher. The heat sensitivity (z value) of the spores was not altered by concentrating the medium. The data from this study can be used to design or evaluate heating processes for concentrated products aiming at the inactivation of B. cereus spores.

Journal

Dairy Science & TechnologySpringer Journals

Published: Jan 15, 2013

References