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Issue Environ. Biosafety Res.
Volume 3, Number 4, October-December 2004
Page(s) 215 - 223
DOI 10.1051/ebr:2005005

Environ. Biosafety Res. 3 (2004) 215-223
DOI: 10.1051/ebr:2005005

Effect of food components and processing parameters on DNA degradation in food

Torsten Bauer1, Walter P. Hammes1, Norbert U. Haase2 and Christian Hertel1

1  Institute of Food Technology, University of Hohenheim, 70593 Stuttgart, Germany
2  Federal Centre for Cereal, Potato and Lipid Research, 32765 Detmold, Germany

(Received April 26, 2004; accepted December 20, 2004)

Abstract
The effect of food components on degradation of DNA by DNase I (EC 3.1.21.1) was monitored by electrotransformation of Escherichia coli, making it possible to determine the number of plasmid molecules capable of giving rise to transformed cells. The transformation frequency increased linearly with the plasmid number within the range of 2 × 106 to 2 × 1010. DNA degradation was reduced by one order of magnitude in the presence of 0.05% (w.v-1) maltol or 1 mM putrescine. Complete inhibition of degradation was observed with $\geq$0.2% (w.v-1) maltol, $\geq$0.01% (w.v-1) octyl gallate or $\geq$0.5 mM of spermine. To monitor degradation of plant DNA during food processing, a real-time PCR system was established. The ratio of copy numbers of a potato gbss DNA fragment of 325 bp and a nested 96 bp fragment was determined. The latter served as internal reference for normalization. The system made it possible to exclude process-dependent changes of DNA concentration in the food matrix. Processing of genetically modified potatoes to dried potato sticks, crisps or flakes was studied and drying steps were shown to exert the strongest effect on DNA degradation, resulting in a drop of the ratio from 0.73 to 0.16.


Key words: food processing / food components / potato / DNA stability / real-time PCR

Corresponding author: Christian Hertel hertel@uni-hohenheim.de

© ISBR, EDP Sciences 2004


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