1. USDA Integrated Pathogen Modeling Program (IPMP 2013). Predictive microbiology is an area of research that applies mathematical models to predict the growth and survival of foodborne pathogens undergoing complex environmental changes. Predictive models are the foundation for microbial food safety risk assessments. ARS researchers at Wyndmoor, Pennsylvania continue to develop and upgrade an easy-to-use integrated data analysis and model development tool that can be used by students and scientists, without any programming knowledge, to develop accurate mathematical models for microbial shelf-life prediction and risk assessments. It has been used in colleges and universities to train students for predictive microbiology research. This regularly upgraded software package is offered as a free tool to scientists and risk modelers around the world and can be downloaded from http://www.ars.usda.gov/Main/docs.htm?docid=23355.
2. Dynamic and Monte Carlo simulation of growth of C. perfringens in uncured cooked beef. C. perfringens is a foodborne pathogen that can cause acute abdominal pain and diarrhea in consumers who ingest cooked meat products that are not properly cooled during manufacturing. Many meat and poultry products regulated by the USDA FSIS may be affected by this pathogen, which may grow rapidly in cooked products during cooling. ARS researchers at Wyndmoor, Pennsylvania developed and validated a new dynamic method to determine the growth kinetics of C. perfringens in uncured cooked beef, and further developed a Monte Carlo computer simulation program to simulate and predict the growth of C. perfringens during dynamic cooling and under isothermal conditions. The new computer simulation program is not only very accurate, but also calculates the probabilities of greater than 1 log and 2 logs in relative growth of C. perfringens in the products. This new computer simulation can be a new tool for the food industry and regulatory agencies to conduct process risk analysis of growth of C. perfringens in uncured cooked meats during cooling, and can significantly enhance the risk management of foodborne illnesses caused by C. perfringens.
3. Enhanced survivability and virulence of STEC exposed to sub-lethal stresses. Fresh produce is commonly washed and cleaned with chlorinated water. ARS researchers at Wyndmoor, Pennsylvania investigated the survival and virulence of Shiga toxin-producing E. coli (STEC) (serotypes O157:H7, O26:H11, O103:H1, O104:H4, O111:NM, O121:NM, and O145:NM) subjected to osmotic (aw 0.95, 0.96, 0.97, and 0.98), acidic (pH 4, 5, 6, and 7) and chlorine stresses (1, 2, and 5 ppm). STEC O145:NM was most resistant to aw stress, O103:H1 to acidic stress, and O26:H11 and O111:NM to chlorine stress. Stressed STEC exhibited increased vero-cytotoxicity. This investigation identifies potential STEC survival mechanisms under food processing conditions and the strategies to control STEC.
4. The use of sorbate to control Listeria monocytogenes on the surface of ready-to-eat (RTE) meat. L. monocytogenes-contaminated RTE meat products have been linked to outbreaks of foodborne illnesses. ARS researchers at Wyndmoor, Pennsylvania modeled the survival and growth of L. monocytogenes on cooked meat packaged with acidified sorbate solution (pH 4-7, sorbate 0-4%) at refrigerated and abuse temperatures (4-12C). The data and models identified the effective conditions for using sorbate to enhance the safety of RTE meats.
5. Modeling heat resistance of Salmonella in ground chicken. Adequate heat treatment destroys Salmonella and is the most effective means to guard against the potential hazards in cooked poultry products. Due to public health concerns regarding toxicity of synthetic chemicals and microbial resistance to such preservatives, consumers these days are increasingly demanding natural products. ARS researchers at Wyndmoor, Pennsylvania defined the heat treatment required to achieve a specific lethality for Salmonella in ground chicken supplemented with natural antimicrobials, gallic acid and eugenol. The predictive model developed can assist food processors to design appropriate thermal processes for the production of chicken products without adversely affecting the quality of the product.
Hwang, C., Huang, L. 2014. Chilled storage of foods - principles. In: Batt, C.A., Tortorello, M.L. (Eds), Encyclopedia of Food Microbiology, vol 1. Elsevier Ltd, Academic Press, pp. 427-431.
Hus, H., Huang, L., Wu, S. 2014. Thermal inactivation of Escherichia coli O157:H7 in strawberry puree and its effect on anthocyanins and color. Journal of Food Science. 79(1):74-80.
Li, C., Huang, L., Chen, J. 2014. Comparative study of thermal inactivation kinetics of Salmonella spp. in peanut butter and peanut butter spread. Food Control. 45:143-149 doi.org/10.1016/j.foodcont.2014.04.023.
Hong, Y., Yoon, W., Huang, L., Yuk, H. 2014. Predictive modeling for growth of non- and cold-adapted Listeria Monocytogenes on fresh-cut cantaloupe at different storage temperatures. Journal of Food Science. doi:10.1111/1750.3841.12468.
Lacombe, A., Tadepalli, S., Hwang, C., Wu, V.C. 2013. Phytochemicals in lowbush wild blueberry inactivate Escherichia coli O157:H7 by damaging its cell membrane. Foodborne Pathogens and Disease. 10:994-950.