PROTEIN PROCESSING USING HIGH-PRESSURE GASES AND SUPERCRITICAL FLUIDS
Location: Eastern Regional Research Center
Title: Removal of Salmonella Enteritidis from commercial† unpasteurized liquid egg white using pilot scale crossflow tangential microfiltration
Submitted to: International Journal of Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 10, 2010
Publication Date: August 1, 2010
Citation: Mukhopadhyay, S., Tomasula, P.M., Luchansky, J.B., Porto Fett, A.C., Call, J.E. 2010. Removal of Salmonella Enteritidis from commercial† unpasteurized liquid egg white using pilot scale crossflow tangential microfiltration. Internationl Journal of Microbiology. DOI: 10.1016/j.ijfoodmicro.2010.07.009.
Interpretive Summary: Shelled liquid egg white (LEW) is heat pasteurized to prevent outbreak of food borne illnesses such as salmonellosis, caused by the presence of the bacteria Salmonella enteritidis. Outbreaks of salmonellosis may still occur with heat treated LEW because not all of the bacteria are killed by the heat. Heating also damages the functional properties of the egg white proteins. We have developed a filtration process which removes the salmonella in LEW, within the limits of detection used in our study, and preserves the delicate functional properties of the LEW. While regulations mandate heat treatment of LEW, a filtration step prior to heating would help ensure the safety of the egg product. This process results in a wholesome LEW product.
The effectiveness of a pilot-scale cross-flow microfiltration (MF) process for removal of Salmonella enteritidis from liquid egg white (LEW) was evaluated. To facilitate MF, 110 L of unpasteurized LEW from a local egg breaking plant was first wedge screened, homogenized and then diluted (1:2 w/w) with distilled water containing 0.5% sodium chloride. The LEW was then inoculated with a cocktail containing five strains of Salmonella enterica serovar Enteritidis (ATCC 4931, ATCC BAA-708, ATCC 49215, ATCC 49218, and ATCC BAA-1045) to a level of approximately 107 cfu/mL of LEW. The LEW was then microfiltered using a ceramic membrane with a nominal pore size of 1.4 'm, at a crossflow velocity of approximately 6 m/s. Influence of process temperature (25 deg C or 40 deg C) and pH of 6, 7, 8 and 9 at each temperature on LEW permeate flux, functional properties and microbial removal efficiency were evaluated. The permeate flux of LEW was greatly enhanced by lowering pH at a constant temperature. Compared to pH, influence of temperature on the permeate flux was minimal. Salmonella removal efficiency was at least 6.8 Log10 cfu/mL (log cfu), with a limit of detection < 0.5 Log10 cfu/mL. The storage stability of the permeate under normal refrigeration temperature of 4 deg C was found to be excellent with no pathogen growth for up to 21 days. However, under abuse storage condition (10 deg C) a slight pathogen outgrowth observed. Functional property analysis indicated that the MF process did not alter the foaming power of LEW. Our data establish that MF prior to pasteurization of LEW has the potential to ensure the safety of LEW while maintaining its nutritional and quality aspects.