Although actual thermal food processes could be regarded as ideal food preservation technologies, the high thermotolerance of certain micro-organisms make necessary heat treatments higher than 90°C for 10 minutes or equivalent lethality. Such treatments induces several chemical changes including the destruction of vitamins and amino acids, lipid oxidation, modification of organoleptic properties, the formation of derivatives or cross-linking products that influence the bioavailability of amino acids and affect also the overall digestion of the proteins. On the other hand, only minimal degradation of nutrients, changes in organoleptic properties as well as formation of new potentially dangerous molecules are expected during non-thermal processes such as High Pressure Homogenization (HPH). 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 evaluate the potential of HPH to inactivate spoilage and pathogenic species in raw milk, whole eggs and fruit juices. The data obtained were compared with those obtained using traditional heat treatments. The target organisms considered were: Salmonella enteritidis and Listeria monocytogenes inoculated in raw milk and whole eggs as well as Saccharomyces cerevisiae and Zygosaccharomyces bailii in apricot and carrot juices. The inoculum levels ranged between 3 and 7 Log CFU/g. The HPH treatments were performed at 100 MPa and repeated up to 8 cycles. The efficacy of the processes was compared with heat treatments at 70°C for different times. The microbiological analyses were performed immediately after the different treatments and during the storage at different temperatures. The survival data of HPH and heat treatments were modeled by using the Baranyi equation. Most of the HPH inactivation curves showed a linear relationship survival vs treatment extent. On the contrary, biphasic curves with survival tails were obtained with thermal treatments. The results showed that, although the microbial deactivation increased with HPH pushes and pasteurization values, the inactivation curves and the recovery during the storage of survivors were dependent on microbial species, food matrices, inoculum levels and food microstructure
High Pressure Homogenization As Alternative To Thermal Treatment To Improve The Microbial Safety, Shelf-life And Functionality Of Fluid Foods And Ingredients
LANCIOTTI, ROSALBA;VANNINI, LUCIA;PATRIGNANI, FRANCESCA;GUERZONI, MARIA ELISABETTA
2008
Abstract
Although actual thermal food processes could be regarded as ideal food preservation technologies, the high thermotolerance of certain micro-organisms make necessary heat treatments higher than 90°C for 10 minutes or equivalent lethality. Such treatments induces several chemical changes including the destruction of vitamins and amino acids, lipid oxidation, modification of organoleptic properties, the formation of derivatives or cross-linking products that influence the bioavailability of amino acids and affect also the overall digestion of the proteins. On the other hand, only minimal degradation of nutrients, changes in organoleptic properties as well as formation of new potentially dangerous molecules are expected during non-thermal processes such as High Pressure Homogenization (HPH). 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 evaluate the potential of HPH to inactivate spoilage and pathogenic species in raw milk, whole eggs and fruit juices. The data obtained were compared with those obtained using traditional heat treatments. The target organisms considered were: Salmonella enteritidis and Listeria monocytogenes inoculated in raw milk and whole eggs as well as Saccharomyces cerevisiae and Zygosaccharomyces bailii in apricot and carrot juices. The inoculum levels ranged between 3 and 7 Log CFU/g. The HPH treatments were performed at 100 MPa and repeated up to 8 cycles. The efficacy of the processes was compared with heat treatments at 70°C for different times. The microbiological analyses were performed immediately after the different treatments and during the storage at different temperatures. The survival data of HPH and heat treatments were modeled by using the Baranyi equation. Most of the HPH inactivation curves showed a linear relationship survival vs treatment extent. On the contrary, biphasic curves with survival tails were obtained with thermal treatments. The results showed that, although the microbial deactivation increased with HPH pushes and pasteurization values, the inactivation curves and the recovery during the storage of survivors were dependent on microbial species, food matrices, inoculum levels and food microstructureI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
