Novel non thermal processes represent an alternative to thermal treatments to improve quality, safety and functionality of fluid foods and ingredients. Among the alternatives proposed, the High Pressure Homogenization (HPH) is one of the most promising technologies and its potential has been applied to the dairy field both for decontamination and product diversification. However, its development and strategic use require a deeper comprehension of its action mechanisms and microbial cells response. The aim of this research, developed within the European project “Innovative non thermal processing technologies to improve the quality and safety of ready-to-eat meals (HighQ RTE)”, was to study the effects of HPH in Saccharomyces cerevisiae and Listeria monocytogenes when exposed to sub-lethal HPH treatments. In S. cerevisiae the membrane fatty acid composition and expression of genes involved in general stress response and lipid biosynthetic routes were analyzed. In Listeria monocytogenes the effects of HPH on gene expression were also studied in comparison with thermal treatments. HPH treatments were performed at 80 MPa on exponential growing cells. Total RNA was extracted, retro-transcribed and cDNA quantified by qRT-PCR. YCL055W, YHR007C, YHR030C, YJR045C, YLR056W were the coding sequences analyzed in S. cerevisiae and 16S RNA, rpoB, opuCA and gad A in L. monocytogenes. The fatty acid profiles of HPH-treated cells of S. cerevisiae were obtained by GC-MS analysis after lipid extraction. In S. cerevisiae a significantly greater proportion of unsaturated fatty acids, such as oleic and palmitoleic acids, was observed in HPH-treated cells with respect to the control. Moreover an increase of desaturase expression compared to housekeeping genes was observed. In L. monocytogenes, the results showed changes of the mRNA level of all the 3 genes rpoB, opuCA and gad A in HPH and heat treated cells. In particular, the expression of rpoB, which is involved in general stress response, was maximal immediately after the treatments after which it decreased

Effects of high pressure homogenization and thermal treatments on gene expression and membrane fatty acid profiles in spoilage and pathogenic food-borne species

VANNINI, LUCIA;RUSSO, ALESSANDRA;DI BIASE, LETIZIA;PATRIGNANI, FRANCESCA;LANCIOTTI, ROSALBA;GUERZONI, MARIA ELISABETTA
2008

Abstract

Novel non thermal processes represent an alternative to thermal treatments to improve quality, safety and functionality of fluid foods and ingredients. Among the alternatives proposed, the High Pressure Homogenization (HPH) is one of the most promising technologies and its potential has been applied to the dairy field both for decontamination and product diversification. However, its development and strategic use require a deeper comprehension of its action mechanisms and microbial cells response. The aim of this research, developed within the European project “Innovative non thermal processing technologies to improve the quality and safety of ready-to-eat meals (HighQ RTE)”, was to study the effects of HPH in Saccharomyces cerevisiae and Listeria monocytogenes when exposed to sub-lethal HPH treatments. In S. cerevisiae the membrane fatty acid composition and expression of genes involved in general stress response and lipid biosynthetic routes were analyzed. In Listeria monocytogenes the effects of HPH on gene expression were also studied in comparison with thermal treatments. HPH treatments were performed at 80 MPa on exponential growing cells. Total RNA was extracted, retro-transcribed and cDNA quantified by qRT-PCR. YCL055W, YHR007C, YHR030C, YJR045C, YLR056W were the coding sequences analyzed in S. cerevisiae and 16S RNA, rpoB, opuCA and gad A in L. monocytogenes. The fatty acid profiles of HPH-treated cells of S. cerevisiae were obtained by GC-MS analysis after lipid extraction. In S. cerevisiae a significantly greater proportion of unsaturated fatty acids, such as oleic and palmitoleic acids, was observed in HPH-treated cells with respect to the control. Moreover an increase of desaturase expression compared to housekeeping genes was observed. In L. monocytogenes, the results showed changes of the mRNA level of all the 3 genes rpoB, opuCA and gad A in HPH and heat treated cells. In particular, the expression of rpoB, which is involved in general stress response, was maximal immediately after the treatments after which it decreased
Evolving microbial food quality and safety
399
400
Vannini L.; Russo A.; Di Biase L.; Patrignani F.; Lanciotti R.; Guerzoni M. E.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11585/73527
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