High Pressure Homogenization to Improve Microbial Safety, Shelf-life and Functionality of Foods and Ingredients

Novel non thermal processes represent an alternative to thermal treatment to improve quality, safety and functionality of milk and milk based products. Among to the alternatives proposed, the High Pressure Homogenization (HPH) is one of the most promising technology and its potential has been especially applied to the dairy field both for the milk decontamination and product diversification. The aim of the research, included in 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 pathogenic species such as Listeria monocytogenes and Salmonella enteritidis in raw milk and eggs and spoilage yeasts, Saccharomyces cerevisiae and Zygosaccharomyces cerevisiae, inoculated in vegetable and fruit juices. In addition, the effects of HPH were evaluated also on the organoleptic quality of milk, milk products and treated juices by using the GC-MS/SPME technique. Moreover also the modifications of viscosity in relation to the entity of the pressure treatment were studied. The data obtained were compared with those obtained using traditional heat treatments. The results regarding the milk decontamination showed that the inactivation curves of S. enteritidis were linear up to the 4th cycle at 100 MPa after which their slopes diminished. Also L. monocytogenes resulted to be sensitive to HPH. A reduction of 5 Log cfu/ml was obtained with 8 pressure pushes at 100 MPa. Concerning the yeast inactivation, the results obtained were very different in relation to the considered species and food matrix. Saccharomyces cerevisiae was very sensitive to HPH when inoculated in carrot juice. As far as viscosity modifications, the most interesting results were obtained for apricot and tomato juices, finding a positive relation with the increase of pressure up to the 5th cycle at 100 MPa.