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United States Department of Agriculture

Agricultural Research Service

2008 Annual Report

1a.Objectives (from AD-416)
Determine the kinetics and mechanisms of inactivation of pathogens and their surrogates by PEF and RFEF technologies; Develop, evaluate and validate PEF and RFEF alone and in combination with other processes to ensure safety and security of fresh apple cider, fresh orange juice and liquid egg; and Evaluate quality, shelf life and cost of products processed by PEF, RFEF and combinational processes, and packaged aseptically or with antimicrobial agents, in comparison to thermal pasteurization.

1b.Approach (from AD-416)
Integrate disciplines of microbiology, engineering and chemistry to provide consumers with safe and high quality food products. Our microbiologists will lead the research in determining the mechanisms and kinetics of microbial inactivation, microbial shelf-life evaluations and product safety evaluations. Our engineers and food technologists will develop and validate novel processes and packaging technologies and evaluate associated cost. Our chemist and food technologists will lead the quality and shelf-life evaluations and consumer acceptance studies. From a food product point of view, the raw food materials will be processed and packaged to ensure safety and to maintain the fresh quality. Process conditions will be determined to achieve the food safety objectives set forth by the log reduction required for the pathogen of concern. Kinetics of microbial inactivation and models provide process set points to achieve food safety objectives. The kinetic models also serve as tools for risk assessment when deviations take place in raw product composition, microbial load and/or processing conditions. Identification of the mechanisms of microbial inactivation will help understand the process and define the direction in process optimization. We will also work with our collaborators in regulatory agencies, industry and other ARS laboratories, to identify the pathogens of concern and suitable surrogates and to define food safety objectives for each product.

3.Progress Report
The performance of media and supplements for the recovery of Salmonella from thermally-treated liquid egg white was examined. These experiments were designed to optimize recovery of heat-injured Salmonella from thermally-treated liquid egg white in line with concurrent USDA Food Safety Inspection Service (FSIS) studies.

We examined the inactivation and injury determination of Lactobacillus plantarum in apple cider by radio frequency electric field (RFEF). We compared potential surrogates for E. coli O157:H7 treated with pulsed electric field (PEF). A CRADA was established with AMC Group of Spain on the scaling up study of PEF process for pasteurization of orange juice products.

Studies on mechanisms of bacteria inactivation in liquid foods by pulse pressure processing were investigated. This study was in collaboration with scientists at the Laboratories of the National Food Research Institute Tsukuba, Japan. The addition of nisin in combination with EDTA was studies to inhibit or inactivate Salmonella and Escherichia coli O157:H7 populations in apple cider.

To simulate commercial juice processing lines, a pilot plant scale pasteurization system is being established. This system consists of a feed tank, pump, thermal or nonthermal pasteurizers and an aseptic bag filler. The system will include PEF, UV, RFEF and SCCO2 processes.

A novel protocol was developed to determine the penetration depth of UV light through liquid egg white and whole liquid egg. Thin films of 0.1 to 0.2 mm depth liquid egg products may be allowed to be effectively processed with UV.

A new supercritical carbon dioxide (SCCO2) processor was provided to ARS for evaluation studies. Escherichia coli K12 in 0.1% buffered peptone water (BPW) and apple cider was tested. Bactericidal effect of SCCO2 was improved at high CO2 concentrations and temperatures. A 5-log reduction of E. coli in 0.1% BPW and apple cider was obtained at all tested temperatures (34, 38, and 42C) with CO2 concentrations ranging from 5.5 to 10% at 1100 psi. The new SCCO2 system is ready for product quality and shelf life studies.

The progress made over last 12 months addressed the NP 108 2006-2010 Action Plan Component 1.2.4 Processing Intervention Strategies by developing a nonthermal pasteurization processes for juices and liquid foods.

1. Antimicrobial packaging for inactivation of Listeria monocytogenes in ready-to-eat meats: Deli meat can occasionally become contaminated by the pathogen Listeria monocytogenes following cooking and prior to packaging, leading to product recalls and foodborne illness outbreaks. The combination of gamma irradiation and antimicrobial packaging was used to inactivate Listeria monocytogenes on the surfaces of deli turkey meat. Pectin films containing 0.025% nisin inactivated 99.99 percent of Listeria on the deli meat. One and 2 kGy doses of ionizing radiation used in combination with nisin/pectin film resulted in additional 99% and 99.95% reductions of Listeria monocytogenes respectively. The combination of irradiation and antimicrobial packaging has the potential to reduce product recalls and foodborne illness outbreaks due to contamination by Listeria monocytogenes. In addition, we also demonstrated the strong antimicrobial activities of Zinc oxide against Listeria monocytogenes, Salmonella Enteritidis and E. coli O157:H7 in culture media or liquid egg. NP 108 Food Safety 2006-2010 Action Plan Component(s) 1.2.4 Processing Intervention Strategies.

2. Quality of non-thermally processed juice products: Consumers and industry need to know if novel processing technologies can provide additional benefits in product quality compared to thermal processing. Thermal processing, the most commonly used technique to reduce spoilage and pathogenic microorganisms in juice products, is known to degrade quality attributes such as color and flavor. We evaluated the non-thermal processing alternatives, pulsed electric field (PEF) and ultraviolet (UV) treatment and their effects on aroma and other quality attributes of apple cider and an orange juice-milk beverage and compared them to thermal pasteurization. PEF better preserved the "fresh" flavor of both products compared with the thermal process, and better extended the shelf-life of apple cider compared with the UV process. The aroma of PEF processed cider was preferred by 91% of panelists over that of thermally processed cider and was described as having stronger apple aroma. The information will help juice processors and consumers to adopt PEF technology for juices and beverages. NP 108 Food Safety 2006-2010 Action Plan Component(s) 1.2.4 Processing Intervention Strategies.

5.Significant Activities that Support Special Target Populations

6.Technology Transfer

Number of Active CRADAs1
Number of Non-Peer Reviewed Presentations and Proceedings4
Number of Newspaper Articles and Other Presentations for Non-Science Audiences1

Review Publications
Fan, X., Geveke, D.J. 2007. Furan formation in sugar solutions and apple cider upon ultraviolet treatment. Journal of Agricultural and Food Chemistry. 55:7816-7821.

Jin, Z.T., Zhang, H.Q., Boyd, G., Tang, J. 2008. Thermal resistance of Salmonella enteritidis and Escherichia coli K12 in liquid egg determined by thermal-death-time disks. Journal of Food Engineering. 84:608-614.

Liu, L.S., Finkenstadt, V.L., Liu, C., Jin, Z.T., Fishman, M., Hicks, K.B. 2007. Preparation of poly(lactic acid) and pectin composite films intended for application in antimicrobial packaging. Journal of Applied Polymer Science, 106(2)801-810.

Geveke, D.J., Brunkhorst, C. 2007. Radio Frequency Electric Fields Inactivation of Escherichia coli in Apple Cider. Journal of Food Engineering. 85:215-221.

Jin, Z.T., Zhang, H.Q. 2008. Biodegradable polylactic acid polymer with nisin for use in antimicrobial food packaging. Journal of Food Science. 73(3):M127-M134.

Bari, M.L., Ukuku, D.O., Mori, M., Kawamoto, S., Yamamoto, K. 2008. Effect of Hydrostatic Pressure Pulsing on the Inactivation of Salmonella Enteritidis in Liquid Whole Egg. Foodborne Pathogens and Disease. 5(2):175-182.

Geveke, D.J., Fan, X., Brunkhorst, C. 2007. Radio frequency electric fields processing of orange juice. Innovative Food Science and Emerging Technologies. 8:549-554.

Last Modified: 11/28/2015
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