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Improving the Control of Bacterial Pathogens on Ready-to-Eat Processed Meats Manufactured to Simulate Traditionally Cured Meats But Without Direct Addition of Nitrite or Nitrate

Mendonca, Aubrey; Dickson, James; Cordray, Joseph; Sebranek, Joseph
Iowa State University
Start date
End date
  1. Evaluate a representative sampling of current commercially available ready-to-eat cured meat products manufactured without added nitrite or nitrate to assess the variability in nitrite and nitrate content, and to measure other properties critical to the quality and safety that is expected of ready-to-eat cured meats.
  2. Assess the hazard associated with the current commercially available ready-to-eat products described above by inoculation challenge with Clostridium perfringens and Listeria monocytogenes.
  3. Identify critical product properties important to safety by identifying and testing ingredients and/or processes that improve safety without altering product properties that are unique.
  4. Validate the effectiveness of the identified ingredients/processes for improved safety by inoculation challenges with C. perfringens, C. botulinum and L. monocytogenes.
  5. Communicate the new information generated from this work to the meat industry through extension short courses, to consumers through electronic media, and to future food processing professionals through undergraduate and graduate educational programs.
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NON-TECHNICAL SUMMARY: Cured meat products manufactured without added nitrite or nitrate represent a potential food safety risk from the potential of greater microbial pathogen growth due to low nitrite levels. This project will determine how to manufacture this category of cured meat products with improved assurance of food safety while retaining the unique properties typical of cured meats.

APPROACH: To initiate the study, commercial samples of ham and frankfurters made without direct addition of nitrite or nitrate will be analized for nitrite, nitrate, cured pigment content, color intensity, salt content and available water. In addition, ingredients (sea salt, vegetable products) used as a source of nitrate for these products will be purchased and analyzed. The ingredients will be stored at refrigerated and room temperature for three months with period analyses of nitrate and nitrite content to determine ingredient variability. The second phase of the project will utilize commercial ham and frankfurter samples from three manufacturers that represent significant variation in product properties. Each sample will be inoculated with Clostridium perfringens or Listeria monocytogenes. The growth of each organism will be monitored during storage of the products to assess the antimicrobial properties of these products. Comparable products manufactured with traditional concentrations of added nitrite will be used as controls. For the third phase of the project, ham and frankfurters will be manufactured with a range of ingredients that provide a source of nitrate for these products. The concentrations of the ingredients will be selected based on results of phases 1 and 2. The manufactured products will be analyzed for nitrite and nitrate content as well as cured pigment formation to assess the extent of curing reactions. The ingredient/processing treatment combination that results in product properties most likely to represent improved bacterial pathogen control will be selected. The fourth phase of this project will then utilize the ingredients and process identified in phase 3 to manufacture ham and frankfurters and the safety of the products validated by inoculation challenges with C. perfringens, C. botulinum and L. monocytogenes. Finally, the information developed will be disseminated to the industry through Iowa State University extension short courses, to consumers by using the Iowa State University food safety web site and to students by incoporating the information into undergraduate and graduate courses.

PROGRESS: 2007/09 TO 2008/08
OUTPUTS: Six different commercially available brands of natural and organic frankfurters have been evaluated for chemical and microbiological properties to assess the potential food safety hazards represented by these products (objectives 1 and 2 of this project). Natural and organic products were most often found to contain significantly less nitrite than conventionally cured products, thus greater growth potential for pathogens exists because nitrite is an important antimicrobial agent. However, one of the commercial products contained approximately 7 times the nitrite concentration of the other natural and organic products (70 ppm vs 0-8 ppm), confirming the hypothesis that the processes used for natural and organic processed meats are highly variable. Inoculation challenges of the commercial products with Clostridium perfringens and Listeria monocytogenes demonstrated that natural and organic products permit growth of these pathogens at a much faster rate than in the case of conventionally cured meats. For C. perfringens, inoculated samples were stored at room temperature, and after 4 days C. perfingens grew from log 1-log 2 to log 7-log 8 in five of the six natural and organic products sampled. The sixth natural and organic product reached similar numbers at day 6. Conventionally cured products remained at about log 2 even after 10 days. Interestingly, the natural and organic product that contained a high concentration of residual nitrite showed relatively rapid growth of C. perfringens. Samples inoculated with L. monocytogenes were held at 10C for 35 days and 3 distinct growth pattern groups were observed. First, conventionally cured products demonstrated little or no increase in numbers of the pathogen. A second group of samples included four natural and organic products which showed a growth delay for the first 4-7 days followed by an increase from log 2-log 3 to log 6-log 8 after 35 days. A third group of natural and organic products showed rapid growth of L. monocytogenes after 2-4 days, reaching log 7-log 8 after 10-14 days. These results have been shared with meat industry personnel as part of Iowa State University extension short courses on meat processing. Further, this information has been included in extension publications and in presentations at professional society meetings (Midwest Poultry Federation-Turkey Processing Workshop, International Congress of Meat Science and Technology).
PARTICIPANTS: Armitra Jackson, Graduate Assistant; Kohl Schrader, Graduate Assistant; Charlwit Kulchiayawat, Graduate Assistant; Gary Sullivan, Graduate Assistant; Joseph G. Sebranek, Distinguished Professor; James S. Dickson, Professor, Aubrey F. Mendonca, Associate Professor, J.C. Cordray, Professor. The project has provided significant training and professional development for the graduate assistants who have been collecting samples, analyzing products and presenting results to extension short course participants and industry personnel. The project also provided professional development opportunity for J.G. Sebranek to travel to the International Congress of Meat Science and Technology in Beijing, China to present and discuss the work accomplished thus far. Finally, the project has resulted in significant collaboration with Dr. Jim Bacus of Technical Ingredient Solutions, LLC (Sarasota, FL) and Florida Fruit Products, Inc. who are providing several natural ingredients that have potential as natural antimicrobials and which will be assessed for effectiveness as the next phase of this project.
TARGET AUDIENCES: The target audiences for the information generated by this project are the small and medium-sized meat processors who need technical assistance to assure safety of natural and organic processed meats. A second target audience is the professional meat science community in industry, universities and government who are responsible for and/or who provide information to the industry on the quality and safety of commercial processed meat products. The information is being delivered to these audiences by technical presentations at scientific meetings, short courses and extension publications. A third target audience is meat industry supervisory personnel who attend the Iowa State University extension short course programs on meat processing, where updates on new developments on product safety and quality are presented. Meat industry personnel are also being targeted by publications and updates provided to meat industry trade magazines such as the National Provisioner, Meatingplace, and Meat and Poultry.

IMPACT: 2007/09 TO 2008/08
Because of the rapidly increasing consumer interest in, and demand for, natural and organic meat products, more and more processors are entering this market. Some have become aware that these products are more susceptible to growth of pathogens and have adopted new technology to improve safety of these products. For example, one of the major meat processors is currently using high pressure processing (HPP) for natural and organic processed meats. This treatment very effectively eliminates a large portion of bacterial cells present and greatly improves safety. Thus, the information on risk associated with natural and organic products that has been one of the outputs of this project has had a major impact on processing procedures adopted for these products. However, the HPP process is not feasible for small and medium-sized meat processors because of equipment cost. Consequently, a second impact area that will be important to this project is the determination and development of natural antimicrobial inhibitors that can provide an alternative to the HPP treatment for improving safety of natural and organic processed meats. This effort is currently underway as part of this project.

PROGRESS: 2006/09/01 TO 2007/08/31
OUTPUTS: Commercially available natural and organic processed meats manufactured without added nitrite or nitrate have been analyzed for chemical and sensory quality characteristics to provide for evaluation of these products as currently available in the marketplace. This has provided a baseline of property characteristics of these products for later comparison of the microbial properties of natural and organic processed meats and for process improvements that might be used to assure or to improve the safety of these products. This is new information on these products that has not been previously available but is now published as a result of this project. This work has addressed the first objective of this project proposal. The initial work on this project has also included determination of the processing variables that are important to the proper manufacturing of these products. This work has defined the procedures and conditions that are important to the successful manufacturing of natural and organic processed meats. The information generated by this project thus far has been disseminated to the scientific community in five peer-reviewed manuscripts recently published in the Journal of Food Science, Meat Science and as a White Paper by the American Meat Science Association. New information has been disseminated to the meat processing industry through presentations to participants in Iowa State University Extension Meat Processing Short Courses that have been conducted since June, 2007.
PARTICIPANTS: Individuals working on this project have included Dr. Joe Cordray, Professor and Meat Extension Specialist who is co-principle investigator and who has provided the opportunity to present results to meat industry personnel as part of meat processing extension short courses. Jeffrey Sindelar did much of the laboratory and product assessment work as a graduate student with major responsibilities for the project. The project provided Dr. Sindelar training as part of his Ph.D. thesis work which was completed this year. Dr. Sindelar is now Meat Extension Specialist at the University of Wisconsin-Madison. This project has also provided training and professional development opportunities for Ms. Armitra Jackson who is currently working on a Ph.D. program that is focused on the microbiological safety of the natural and organic processed meats, and on the process changes that may be needed to assure or improve the microbiological safety relative to the commercial products currently available. Dr. James Bacus of Chris Hansen, Inc. has been a valuable collaborator. Dr. Bacus has supplied some of the unique ingredients used in natural and organic processed meats for test batches that were part of this project and has provided valuable information on current industry practices used in the manufacture of these products.
TARGET AUDIENCES: The target audiences include the professional meat science community (meat scientists and meat extension specialists) who are responsible for providing updated information to the meat industry for meat processing technologies, and who are receiving the new information by means of peer reviewed scientific publications. The target audiences also include the meat industry personnel who manage production procedures for natural and organic processed meats, and who are responsible for commercial product quality and safety. This audience has received the new information through the Iowa State University Meat Processing Short Course Program, Iowa State University extension publications and through trade magazine articles.

IMPACT: 2006/09/01 TO 2007/08/31
The results of the work thus far have demonstrated that natural and organic processed meats are more variable in many attributes including residual nitrite and lipid oxidation than typically observed in conventionally cured meat products. This means that quality and probably safety is also more variable. Sensory panelists found the natural and organic products to be less acceptable in some cases than the conventional products, an observation that supports the variation found by chemical measures of product properties. The information about product variability has, based on feedback from extension clientele, already resulted in changes in industry procedures that should result in more uniform and more consistent naturally cured meat product properties. This also means that the subsequent objectives of this project, that is, the assessment and improvement of microbial safety of these products are clearly needed and the initial hypothesis for this work is substantiated.

Funding Source
Nat'l. Inst. of Food and Agriculture
Project source
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Project number
Accession number
Natural Toxins
Viruses and Prions
Bacterial Pathogens
Chemical Contaminants
Education and Training
Meat, Poultry, Game