Submitted to: Food Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/9/2012
Publication Date: 7/1/2012
Citation: Mukhopadhyay, S., Ukuku, D.O., Phillips, J.G., Juneja, V.K. 2012. Survival and growth of Salmonella Enteritidis in membrane processed liquid egg white with pH, temperature and storage conditions as controlling factors. Food Microbiology. 75(7):1219-1226. Interpretive Summary: Salmonella Enteritidis is a bacterium which is responsible for salmonellosis,a serious food borne illnesses which has important economic implications and pose serious obstacle to the well-being of consumers. Salmonella contamination of eggs is a recurring problem. By law,liquid egg white(LEW)is required to be pasteurized at 56.6C for minimum 3.5 min before consumption. This heating damages the functional properties of the egg white proteins. This study shows that microfiltration (MF),which uses micron-sized filters can remove Salmonella and other organisms from LEW without affecting the functionality and that pH and temperature influence the effectiveness of Salmonella removal. Findings from this study would be helpful to develop optimum processing conditions for liquid egg industries.
Technical Abstract: A study was undertaken to determine the effect of variation in solution pH and process temperature on the removal and regrowth of Salmonella Enteritidis in liquid egg white (LEW) by microfiltration (MF) membrane process. Influence of various storage conditions on growth of Salmonella in membrane separated LEW were also evaluated. Pretreated and pH adjusted (pH6 to pH9) LEW was inoculated with a five strain mixture of Salmonella enterica serovar Enteritidis at ca. 7 log colony-forming units (CFU/mL), microfiltered at 25C or 40C, and stored at 4C or 10C. Salmonella populations in permeate differed based on variations in experimental pH, temperature or storage condition. (p less than 0.05). Temperature had greater influence on Salmonella spp. reduction compared to pH. Maximum reduction of Salmonella and background microflora in LEW by MF was observed at 40C and pH 8 and 9. However,influence of temperature on permeate flow was less effective compared to the influence of pH. The mean permeate flow increased by 180% at 25C as the pH decreased from 9 to 6, while flow increased merely by 18% at pH6 as temperature increased from 25C to 40C. Salmonella population in processed LEW at 4C storage remained quite stable (0.01 – 0.55 log CFU/mL), irrespective of MF experimental condition. At 10C the population was higher but no major outgrowth observed. Findings from this study would be advantageous to liquid egg processing industries.