Abstract #376

Section: Dairy Foods (orals)
Session: Dairy Foods: Recent Advances in Dairy Food Safety Research
Format: Oral
Day/Time: Tuesday 3:45 PM–4:15 PM
Location: Room 237/238
Recorded Presentation is being recorded
# 376
Controlling Listeria monocytogenes in soft cheese with high voltage atmospheric cold plasma (HVACP) treatment.
K. M. Keener*1, Z. Wan1, 1Iowa State University, $Ames, IA,.

Queso Fresco (QF), a type of Hispanic-style soft and fresh cheese, is a popular food in Latin-American diet. Because of its high moisture content, near neutral pH, and moderate salt content, QF provides an optimal substrate for the growth of spoilage and pathogenic microorganisms. Currently, there are no effective commercial technologies to reduce microorganisms in soft cheeses such as QF. High voltage atmospheric cold plasma (HVACP) is a novel, non-thermal technology, which can be used to treat packaged food products and achieve significant reduction of pathogenic and spoilage microorganisms without compromising products’ qualities. In this study, various gases, such as dry air and MA50 (50% CO2, 50% N2), were evaluated for inactivation of Listeria innocua (LI), a non-pathogenic surrogate for Listeria monocytogenes, in QF by HVACP treatment. Survival LI after HVACP treatments were enumerated on Listeria selective agar and by thin agar layer method for injured cell enumeration. Quality effects were analyzed for lipid oxidation, pH, color, texture and moisture content. Plasma characterization was done using optical emission spectrometry. The results have shown that a maximal of 4.9 log10 cfu/g LI reduction was achieved after dry air HVACP treatment. A slight increase in lipid oxidation was observed in QF samples after HVACP treatment in dry air. Negligible changes were observed in color, texture, moisture content and pH after HVACP treatments. Moreover, after direct HVACP treatments in dry air, LI population decreased with longer storage at 4°C. After 28 d, 1.4 log10 cfu/g LI population was found on treated QF while 7.4 log10 cfu/g was observed in control samples. Lastly, HVACP treatment in dry air reduced and inhibited the growth of background microorganisms. After 28 d of storage at 4°C, less than 2.0 log10 cfu/g background microorganisms was observed in treated QF, while more than 6.0 log10 cfu/g was recorded in control samples. The results demonstrate the efficacy of HVACP treatment for LI inactivation in QF and the potential of HVACP technology for non-thermal processing of delicate dairy products.

Key Words: atmospheric cold plasma, Listeria innocua, Queso Fresco cheese

Speaker Bio
Dr. Kevin Keener is a Professor of food science and technology at Iowa State University in the
Department of Food Science and Human Nutrition. His academic program is focused on addressing global issues such as food safety, food waste, food sustainability, and food security through the development of novel food manufacturing technologies, including food packaging. Over his career, Dr. Keener has garnered over $2.5 million dollars in funding. He has published over 70 refereed publications, 40 technical publications, 50 non-refereed publications, ten book chapters, been awarded ten patents, and delivered more than 60 invited presentations to over 1,000 persons in 16 countries.
Additionally, he has delivered over 100 workshops on food safety, food processing, food regulations, food technology, and food sustainability. He has graduated ten graduate students (MS and Ph.D.), supervised eight post-doctoral students and mentored over 75 undergraduate student researchers. He has received a number of awards for his research, extension, and Center programs such as Fellow of the Am. Soc. of Ag. and Bio. Eng. (ASABE), the Iowa State University’s Iowa Economic Development Award, Institute of Food Technologists’ Research and Development Award, Purdue University’s Spirit of the Land Grant Award, ASABE Rainbird Engineering Concept of the Year Award, American Egg Board
Research Award, International Food Engineering Award, and many others.