Design and evaluation of a high hydrostatic pressure combined process for pasteurization of liquid whole egg

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Abstract This paper evaluates the possibilities of a high hydrostatic pressure (HHP) combined process as an alternative to liquid whole egg (LWE) heat pasteurization. In a first step, HHP boundary conditions with a certain impact on LWE viscosity were established. Secondly, the lethality of HHP at those boundary conditions, alone or combined with temperature or triethyl citrate – E1505 – (TC) followed by heat, on the inactivation of Listeria innocua BGA 3532 (Listeria genus surrogate) and Escherichia coli K12 (Salmonella Enteritidis surrogate in liquid egg) was investigated. HHP treatments that increased viscosity less than current heat pasteurization of 60 °C/3.5′ (20% increment in viscosity), reduced 1.5 and 0.6 Log10 the population of E. coli and L. innocua, respectively. These results indicated that HHP technology at 20 °C was unsuitable for LWE pasteurization without affecting its physical properties. HHP applied at 4 or 50 °C increased lethality but insufficiently to assure LWE safety. The addition of 2% TC resulted in a synergistic lethal effect of HHP at 20 or 4 °C, reducing the heat resistance of both microorganisms. Combined processes based on the successive application of HHP at 20 °C (300 MPa/3′) and heat (52 °C/3.5′ or 55 °C/2′) to LWE with 2% TC reduced more than 5 Log10 in E. coli and L. innocua with better physic-chemical and functional properties than the ultrapasteurization heat treatment (71 °C/1.5′). Industrial relevance A new alternative to heat pasteurization is proposed in this investigation. The successive application of low intensity treatments of high hydrostatic pressure (300 MPa/3 min) followed by heat (52 °C/3.5 min or 55 °C/2 min) to liquid whole egg (LWE) in presence of 2% triethyl citrate would offer LWE with the same microbial safety level than the industrially treated at 71 °C/1.5 min but with quality properties similar to fresh LWE.