2013 Annual Report
1A: Pathogen Behavior in RTE Foods, Liquid Egg Products, and Produce - Measure and model pathogen growth in RTE foods, liquid egg products, and pre-packaged produce as a function of intrinsic and extrinsic factors, pathogen strain and physiological state, and natural background microflora.
1B: Thermal Inactivation Studies - Define combinations of intrinsic and extrinsic factors that delineate minimum heat treatments for pathogen lethality.
1C: Time-Temperature Conditions for Cooling Cooked Meat - Evaluate excessive time in cooling of heated meat and poultry products supplemented with additives to determine if the product remains safe.
2. Develop methods for application in predictive microbiology that are allied to Objective 1. For example: computer simulation of bacterial growth and inactivation under dynamic conditions, and simulation of the growth, inactivation and survival of foodborne pathogens in the presence of competing background flora.
3. Extend technology transfer through the expansion and continued maintenance of the Pathogen Modeling Program (PMP) and the Predictive Microbiology Information Portal (PMIP). Develop a computational framework to make the PMP compatible with Combase, and continue to support the development of ComBase with our associated partners (the Institute of Food Research [IFR] and the University of Tasmania [UTAS]) as an international data resource.
Salmonella is a major foodborne pathogen frequently associated with products of poultry origin and can cause illnesses in consumers of all age groups. If contaminated, liquid egg products can pose serious risks to public health. Research was conducted to understand how this bacterium grows in liquid egg products. The results from this study can be used by the food industry to predict the growth of Salmonella in liquid eggs during storage and distribution and by regulatory agencies to conduct risk assessments.
Salmonella was also implicated in foodborne infections caused by contaminated peanut butter. Due to low moisture and high fat contents in peanut butter, Salmonella can be difficult to kill by heat. Research was conducted to investigate the effect of fat and sugar contents on the survival of Salmonella in peanut butter during thermal processing. The results from this study can be used to design thermal processes to effectively kill Salmonella in contaminated peanut butter.
Strawberries are the fifth preferred fresh fruit in the U.S. and can be contaminated by E. coli O157:H7. Once contaminated, they must be pasteurized prior to consumption. Research was conducted to investigate the survival of E. coli O157:H7 in strawberry puree during thermal processing and the effect of heat on degradation of anthocyanins and development of color. Results showed that microwave heating can effectively inactivate E. coli O157:H7 without affecting anthocyanins and color, while a slight degradation of anthocyanins and color development was observed during conventional heating. Results from this study can be used by the food industry to develop effective heating methods to inactivate E. coli O157:H7 in strawberry puree without causing degradation in anthocyanins and color.
Studies were conducted to examine the growth behavior of acid-stressed (cell exposure, pH 4-6) and acid-adapted (growth exposure, pH 5-6.5) E. coli O157:H7 on lettuce and spinach. Experiments on the effects of chlorine stress on the growth and virulence of E. coli O157 in produce and meat are in progress. Mathematical models will be developed to describe the stresses of acid and chlorine on E. coli O157:H7.
Experiments to determine the germination and outgrowth of Clostridium perfringens spores during cooling of cooked pork products were completed. Dynamic cooling experiments from 54.4 to 4.4 degree C in 6.5 to 21 hours are being conducted. A predictive model based on the product composition factors is being developed.
Huang, L. 2012. Mathematical modeling and numerical analysis of the growth of Non-O157 shiga toxin-producing Escherichia coli in spinach leaves. International Journal of Food Microbiology. p. 32-41. 10.1016/j.ijfoodmicro.2012.09.019.
Ding, T., Wang, J., Park, M., Hwang, C., Oh, D. 2013. A probability model for enterotoxin production of Bacillus cereus as a function of pH and temperature. Journal of Food Protection. 76(2)343-347.
Huang, L. 2013. Optimization of a new mathematical model for bacterial growth. Journal of Applied Microbiology. 32:283-288.
Fang, T., Liu, Y., Huang, L. 2013. Growth kinetics of Listeria monocytogenes and spoilage microorganisms in fresh-cut cantaloupe. Food Microbiology. http://dx.doi.org/10.1016/j.fm.2012.12.05.
Huang, L. 2013. Determination of thermal inactivation kinetics of Listeria monocytogenes in chicken meat by isothermal and dynamic methods. Food Control. 33:484-488.
Hwang, C., Huang, L., Sheen, S., Juneja, V.K. 2012. Effects of lactic acid on the growth characteristics of Listeria monocytogenes on cooked ham surfaces. Journal of Food Protection. 75(8)1404-1410.
Lin, L., Martinez, C.V., Redondo, M., Juneja, V.K., Burson, D.E., Harshavardhan, T. 2012. Inhibition of Clostridium perfringens spore germination and outgrowth by lemon juice and vinegar product in reduced NaCl roast beef. Journal of Food Science. 77(11)598-603.
Juneja, V.K., Baker, D.A., Harshavardhan, T., Snyder, O.P., Mohr, T.B. 2013. Growth potential of Clostridium perfringens from spores in acidified beef, pork and poultry products during chilling. Journal of Food Protection. 76(1):65-71.
Redondo-Solano, M., Valenzuela-Martinez, C., Cassada, D., Snow, D.D., Burson, D.E., Juneja, V.K., Thippareddi, H. 2013. Effect of meat ingredients (sodium nitrite and erythorbate) and processing (vacuum storage and packaging atmosphere) on germination and outgrowth of Clostridium perfringens spores in ham during abusive cooling . Food Microbiology. 35:108-115.
Juneja, V.K., Gonzales-Barron, U., Butler, F., Yadav, A.S., Friedman, M. 2013. Predictive thermal inactivation model for the combined effect of temperature, cinnamaldehyde and carvacrol on starvation-stressed multiple Salmonella serotypes in ground chicken. International Journal of Food Microbiology. 165:184-199.
Juneja, V.K., Hwang, C., Sheen, S., Friedman, M., Altuntas, E., Ayhan, K. 2013. Predictive model for the reduction of heat resistance of Listeria monocytogenes in ground beef by the combined effect of sodium chloride and apple polyphenols . International Journal of Food Microbiology. 164:54-59.
Chmielewski, R.A., Beck, J.R., Juneja, V.K., Swayne, D.E. 2013. Inactivation of low pathogenicity notifiable avian influenza virus and lentogenic Newcastle disease virus following pasteurization in liquid egg products. LWT - Food Science and Technology. 52(1):27-30.