Milk is a highly consumed product worldwide mainly because of nutrient content, but this rich composition associated to pH and water activity makes the milk an ideal medium for microbial growth. The thermal process is usually applied to guarantee microbial stability of milk, however, the heat promotes undesirable changes in the milk sensory and nutritional characteristics. Therefore, recent researchers have developed alternative non-thermal methods to obtain safe milk. High pressure homogenization (HPH) is based upon common milk homogenization processes, though it uses 10-15 times higher pressures, which makes the process able to promotes microbiological reduction. This review evaluated the application of HPH into fluid milk processing for microbiological reduction and also how the process condition (i.e. pressure, inlet temperature) and milk composition can affect the efficacy of this new process. © 2008 IFRJ, Faculty of Food Science & Technology, UPM.19115Briñez, W.J., Roig-Sagués, A.X., Herrero, M.M.H., López, B.G., Inactivation of Staphylococcus ssp. Strains in whole milk and orange juice using ultra high pressure homogenization at inlet temperatures of 6 and 20°C (2007) Food Control, 18, pp. 1282-1288Campos, F.P., Cristianini, M., Inactivation of Saccharomyces cerevisiae and Lactobacillus plantarum in orange juice using ultra high-pressure homogenization (2007) Innovative Food Science and Emerging Technologies, 8, pp. 226-229Chaves-López, C., Lanciotti, R., Serio, A., Paparella, A., Guerzoni, E., Suzzi, G., Effect of high pressure homogenization applied individually or in combination with other mild physical or chemical stresses on Bacillus cereus and Bacillus subtilis spore viability (2009) Food Control, 20, pp. 9691-9695Cromie, S., Psychrotrophs and their enzyme residues in cheese milk (1992) Australian Journal of Dairy Technology, 47 (2), pp. 96-100Diels, A.M.J., Wuytack, E.Y., Michiels, C.W., Modeling inactivation of Staphylococcus aureus and Yersinia enterocolitica by high-pressure homogenization at different temperatures (2003) International Journal of Food Microbiology, 87, pp. 55-62Diels, A.M.J., Callewaert, L., Wuytack, E.Y., Masschalck, B., Michiels, C.W., Moderate temperatures affect Escherichia coli inactivation by high-pressure homogenization only through fluid viscosity (2004) Biotechnology Progress, 20 (5), pp. 1512-1517Diels, A.M.J., Callewaert, L., Wuytach, E.Y., Masschalck, B., Michiels, C.W., Inactivation of Escherichia coli by high-pressure homogenenization is influenced by fluid viscosity but not by water activity and product composition (2005) International Journal of Food Microbiology, 101, pp. 281-291Diels, A.M.J., Michiels, C.W., High-pressure homogenization as a non-thermal technique for the inactivation of microorganisms (2006) Critical Reviews in Microbiology, 32, pp. 201-216Fantin, G., Fogagnolo, M., Guerzoni, M.E., Lanciotti, R., Medici, A., Pedrini, P., Rossi, D., Effects of high hydrostatic pressure and high pressure homogenization on the enantioselectivity of microbial reductions (1996) Tetrahedron: Asymmetry, 7 (10), pp. 2879-2887Floury, J., Bellettre, J., Legrand, J., Desrumaux, A., Analysis of a new type of high pressure homogeniser. A study of the flow pattern (2004) Chemical Engineering Science, 59 (4), pp. 843-853Gomes, M.I.F.V., (1995) Contribuição ao estudo da atividade proteolítica residual sobre a estabilidade proteica do leite esterilizado "longa vida", , Thesis (phD in Food Technology)-Faculty of Food Engineering, State University of CampinasGuerzoni, M.E., Vannini, L., Chaves-Lopez, C., Lanciotti, R., Suzzi, G., Gianotti, A., Effect of high pressure homogenization on microbial and chemicophysical characteristics of gota cheese (1999) Journal of Dairy Science, 82, pp. 851-862Hayes, M.G., Kelly, A.L., High pressure homogenization of raw whole bovine milk (a) effects on fat globule size and other properties (2003) Journal of Dairy Research, 70 (3), pp. 297-305Hayes, M.G., Kelly, A.L., High pressure homogenization of milk (b) effects on indigenous enzymatic activity (2003) Journal of Dairy Research, 70 (3), pp. 307-313Hayes, M.G., Fox, P.F., Kelly, A.L., Potential applications of high pressure homogenization in processing of liquid milk (2005) Journal of Dairy Research, 72 (1), pp. 25-33Innings, F., Trägardh, C., Analysis of the flow field in a high-pressure homogenizer (2007) Experimental thermal and Fluid Science, 32, pp. 345-354Iucci, L., Patrignani, F., Vallicelli, M., Guerzoni, M.E., Lanciotti, R., Effects of high pressure homogenization on the activity of lysozyme and lactoferrin against Listeria monocytogenes (2007) Food Control, 18, pp. 558-565Kelemen, M.V., Sharpe, J.E.E., Controlled cell disruption: a comparison of the forces required to disrupt different microorganisms (1979) Journal of Cellular Science, 35, pp. 431-441Kheadr, E.E., Vachon, J.F., Paquin, P., Fliss, I., Effect of dynamic high pressure on microbiological, rheological and microstructural quality of Cheddar cheese (2002) International Dairy Journal, 12 (5), pp. 435-446Kleinig, A.R., Middelberg, A.P.J., On the mechanism of microbial cell disruption in high pressure homogenization (1998) Chemical Engineering Science, 53 (5), pp. 891-898Lacroix, N., Fliss, I., Makhlouf, J., Inactivation pf PME and stabilization of opalescence in orange juice by dynamic high pressure (2005) Food Reseach International, 38, pp. 569-576Lanciotti, R., Patrignani, F., Iucci, L., Saracino, P., Guerzoni, M.E., Potential of high pressure homogenization in the control and enhancement of proteolytic and fermentative activities of some Lactobacillus species (2007) Food Chemistry, 102, pp. 542-550Middelberg, A.P.J., Process-scale disruption of microorganisms (1995) Biotechnology Advances, 13, pp. 491-551Nielsen, S.S., Plasmin System and Microbial Proteses in milk: characteristics, Roles, And Relationship (2002) Journal of Agricultural and Food Chemistry, 50 (22), pp. 6628-6634Paquin, P., Technological properties of high pressure homogenisers: the effect of fat globules, milk proteins, and polysaccharides (1999) International Dairy Journal, 9, pp. 329-335Pereda, J., Jaramillo, D.P., Quevedo, J.M., Ferragut, V., Guamis, B., Trujillo, A.J., Characterization of volatile compounds in ultra-high-pressure homogenized milk (2008) International Dairy Journal, 18 (8), pp. 826-834Picart, L., Thiebaud, M., René, M., Guiraud, J.P., Cheftel, J.C., Dumay, E., Effects of high pressure homogenisation of raw bovine milk on alkaline phosphatase and microbial inactivation (2006) A comparison with continuous short-time thermal treatments. Journal of Dairy Research, 73 (4), pp. 454-463Ramaswamy, H.S., Shao, Y., Zhu, S., Highpressure destruction kinetics of Clostridium sporogenes ATCC 11437 spores in milk at elevated quasiisothermal conditions (2010) Journal of Food Engineering, 96 (2), pp. 249-257Roach, A., Harte, F., Disruption and sedimentation of casein micelles and casein micelle isolates under high-pressure homogenization (2008) Innovative Food Science and Emerging Technology, 9, pp. 1-8Roig-Sagués, A.X., Velázquez, R.M., Montealegre-Agramont, P., López-Pedemonte, T.J., Briñez-Zambrano, W.J., Guamis-López, B., Hernandez-Herrero, M.M., (2009) Fat content increases the lethality of ultra-high-pressure homogenization on Listeria monocytogenes in milk, 92 (11), pp. 5396-5402Shah, N.P., Psychrotrophs in milk: a review (1994) Milchwissenschaft, 49 (8), pp. 432-437Smiddy, M.A., Martin, J.-E., Huppertz, T., Kelly, A.L., Microbial shelf-life of high-pressurehomogenized milk (2007) International Dairy Journal, 17, pp. 29-32Sun, H., Kawamura, S., Himoto, J.-I., Itoh, K., Wada, T., Kimura, T., Effects of Ohmic Heating on Microbial Counts and Denaturation of Proteins in Milk (2008) Food Science and Technology Research, 14 (2), pp. 117-123Tahiri, I., Makhlouf, J., Paquin, P., Fliss, I., Inactivation of food spoilage bacteria and Escherichia coli O157:H7 in phosphate buffer and orange juice using dynamic high pressure (2006) Food Research International, 39, pp. 98-105Thiebaud, M., Dumay, E., Picart, L., Guiraud, J.P., Cheftal, J.C., High-pressure homogenization of raw bovine milk. Effects on fat globule size distribution and microbial inactivation (2003) International Dairy Journal, 13 (6), pp. 427-439Tribst, A.A.L., Franchi, M.A., Cristianini, M., Ultra-high pressure homogenization treatment combined with lysozyme for controlling Lactobacillus brevis contamination in model system (2008) Innovative Food Science and Emerging Technology, 9 (3), pp. 265-271Tribst, A.A.L., Franchi, M.A., Cristianini, M., de Massaguer, P.R., Inactivation of Aspergillus niger in mango nectar by high-pressure homogenization combined with heat shock (2009) Journal of Food Science, 74 (9), pp. M509-M514Tribst, A.A.L., Sant'ana, A.S., de Massaguer, P.R., Review: Microbiological quality and safety of fruit juices-past, present and future perspectives (2009) Critical Reviews in Microbiology, 35 (4), pp. 310-339Tribst, A.A.L., Franchi, M.A., Cristianini, M., de Massaguer, P.R., Quality of Mango Nectar Processed by High-Pressure Homogenization with Optimized Heat Treatment (2011) Journal of Food Science, 76 (2), pp. M106-M110Vachon, J.F., Kheadr, E.E., Giasson, J., Paquin, P., Fliss, I., Inactivation of foodborne pathogens in milk using dynamic high pressure (2002) Journal of Food Protection, 65, pp. 345-352Vannini, L., Lanciotti, R., Baldi, D., Guerzoni, M.E., Interactions between high pressure homogenization and antimicrobial activity of lysozyme and lactoperoxidase (2004) International Journal of Food Microbiology, 94 (2), pp. 123-135Walkling-Ribeiro, M., Noci, F., Cronin, D.A., Lyng, J.G., Morgan, D.J., Antimicrobial effect and shelf-life extension by combined thermal and pulsed electric field treatment of milk (2009) Journal of Applied Microbiology, 106, pp. 241-258Wuytack, E.Y., Diels, A.M.J., Michiels, C.W., Bacterial inactivation by high-pressure homogenization and high hydrostatic pressure (2002) International Journal of Food Microbiology, 77, pp. 205-212