Progress 09/01/09 to 08/31/13
Outputs
Target Audience: Small-scale food processors, entrepreneurs, farm-based producers, restaurateurs, federal and state food inspectors, extension educators, food safety specialists. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Two graduate students obtained their M.S. degrees in Food Science and Human Nutrition with a focus on food safety, Suzanne Agro (Advisor, Dr. Al Bushway) and Stephanie Wolfe (Advisor, Dr. Beth Calder) at the University of Maine. We also trained two undergraduates (1 human nutrition student and 1 food science student) and two graduate food science students on how to properly analyze acid, formulated acid and acidified food products in the laboratory during the grant period. At Cornell University, one student obtained her M.S. degree (Elizabeth Sullivan), one her M.P.S. degree (Xiofan Gao) and five other graduate students participated in different studies (with authorship on publications). Two additional graduate students participated in extension activities. How have the results been disseminated to communities of interest? Research results have been presented at the Institute of Food Technologists Annual Meeting, the International Association for Food Protection Annual Meeting, local/regional presentations to small-scale food processors, extension educators and regulatory personnel. Results have also being disseminated by peer-review publications, one book chapter, through the website, and by knowledge transfer to individual processors via workshops and one-on-one counseling/mentoring when working with them to determine best formulation and processing/packaging procedures to achieve a safe and stable food product. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
This project enhanced the safety of over 3,500 acid and acidified (pickled) foods manufactured by over 1,000 small-scale processors, farmers and entrepreneurs in the Northeast by providing science-based guidelines to assure a safe product in compliance with regulations. Applied research studies were conducted to expand knowledge needed where limited information was available. Training programs and educational materials were developed to transfer the knowledge to over 250 processors. Graduate training opportunities were given to eleven students by direct contribution in the research and extension activities covered by this project. Objectives 1 and 2: We assessed knowledge gaps and scientific status of formulation and processing parameters used to determine critical control points for safe manufacture of acid and acidified foods by small-scale processors by conducting pertinent literature reviews, and by direct input from small scale processors and regulatory personnel. Training needs were also determined which concentrated on regulatory compliance (regulations and recordkeeping), formulation, processing and packaging, and measurable critical control points to ensure safety and stability. During the grant period, we worked with over 1,080 small-scale processors to ensure the safety of 3,560 food products by issuing schedule processes for regulatory compliance. We evaluated over 5,080 food samples for safety and stability (representing 33 states). We developed educational materials and training modules to address the needs of processors and entrepreneurs, with 250 people receiving customized training. Ninety percent of attendees to most recent program found the demonstrations and videos useful/very useful, with ratings of 4.4-4.8/5.0. The demonstration videos, complete set of recordkeeping templates, FDA process filing presentation, and educational modules are available in the NECFE/Acid and Acidified Foods website of Cornell University. This information is being updated as the new Food Safety Modernization Act is implemented, and it is currently being used as a complement to the Acidified Foods BPCS program while approval by regulatory agencies is achieved. Objective 3: Challenge studies were needed to determine safety parameters for cold packing acid and acidified foods. A shelf-stability of cold-packed grape juice with different preservatives was conducted (peer-reviewed paper published). We studied the shelf-stable pickled eggs case, which represents one of the most extreme products in terms of nutrient availability to pathogens, slow acidification rate and high buffer capacity, in the 3.8-4.4 pH range typically used by processors. Results with four pertinent pathogens (Salmonella, L. monocytogenes, E. coli O157:H7 and S. aureus) showed that acetic acid was effective in killing pathogens, and that acidification of the egg yolk below pH 4.6 requires 5-9 days, thus the need to refrigerate the product first, followed by a hold time of 7 days at room temperature to achieve more than 5-log reduction of pathogens. The results have been presented at professional meetings and 2 peer-review publications (from 2 graduate student theses) were produced, with appropriate safety recommendations. We also conducted challenge studies with three pathogens (Salmonella, L. monocytogenes, and E. coli O157:H7) on four salad dressings (covering the typical pH range of 3.3-3.9) based on commercial formulations with a variety of ingredients (roasted garlic, cranberry, ginger, fig, strawberry, oil, vinegar and others). Results demonstrated the need to allow for a proper hold time at room temperature of up to 10 days depending on pH and formulation, to ensure the safety of cold packed salad dressings. A peer-reviewed publication (from 2 graduate student theses) is being prepared to disseminate these results. Objective 4: In addition to cold packing, we performed acidification and thermal processing studies using model systems to evaluate effect of organic acids and heating on safety and stability. The effect of varying pH with different organic acids on the thermal inactivation of non-acid adapted and acid-adapted E. coli O157:H7 (strain C7927) was determined. D and z-values were calculated for non-acid adapted E. coli in an apple-carrot juice blend (80:20) adjusted to three pH values (3.3, 3.5, and 3.7) by addition of lactic, malic, or acetic acid, and at a pH of 4.5 adjusted with NaOH. D-values were determined at 54, 56, and 58°C. For juices acidified to the same endpoint pH with different acids, E. coli was found more tolerant in samples acidified with malic acid, followed by lactic, and acetic. Data from this study is useful for establishing critical limits for safe thermal processing of pH controlled juices and similar products. Results were presented at professional meetings and one peer-reviewed publication was already produced. A shelf-life study was also conducted with the same juice blend acidified with malic or acetic acids (pH 3.3, 3.5 and 3.7), filled at 63, 71 and 77ºC into glass or PET bottles, confirming the importance of proper acid selection and hot-fill temperature. Shelf-stable pickled products are thermally processed to ensure safety and stability. Carrots packed in glass jars and processed in a boiling water bath were chosen to construct a model to predict accumulated lethality values given process conditions and heating times, when product pH ranges from < 3.9 to 4.4, including jar size, carrots to brine ratio, carrot spear diameter, brine temperature, blanching or not prior to filling. The constructed model will allow processors to determine the time needed to thermally process similar products at given process conditions to achieve accumulated lethality values between 0.1 and 10 minutes (Tref = 93 °C, z = 9 °C). The results were presented at a professional meeting and peer-review publications will follow. All the research results are being used to ensure the safety of acid and acidified foods, and specifically to be able to issue schedule processes for new food products.
Publications
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2011
Citation:
Gao, X. (2011). The Effect of Acetic Acid Concentration and Fill and Storage Temperatures on Acid Penetration and Texture on Pickled Eggs (Masters of Professional Studies Thesis). Cornell University, Ithaca, NY.
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2013
Citation:
Sullivan, E. (2013). Identification of Critical Parameters for the Microbiological Safety and Stability of Select Acidified Foods (Masters Thesis). Cornell University, Ithaca, NY.
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2012
Citation:
Agro, S. (2012). The Effects of pH on Pathogen Death Rate (Escherichia coli O157:H7, Salmonella and Listeria monocytogenes) in Minimally Processed, Shelf-Stable, Non-dairy Dressings (Masters Thesis). University of Maine, Orono, ME.
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2012
Citation:
Wolfe, S. (2012). Survival of Salmonella, Escherichia Coli O157:H7, Listeria Monocytogenes in pH-Adjusted Salad Dressings (Masters Thesis). University of Maine, Orono, ME.
- Type:
Journal Articles
Status:
Accepted
Year Published:
2013
Citation:
Acosta, O., Sullivan, E.K., Gao, X., Padilla-Zakour, O.I. 2013. Pickled Egg Production: Effect of Brine Acetic Acid Concentration and Packing Conditions on Acidification Rate . J. Food Protect. (JFP-13-362). Accepted
- Type:
Journal Articles
Status:
Awaiting Publication
Year Published:
2013
Citation:
Usaga, J., Worobo, R.W., Padilla-Zakour, O.I. 2013. Thermal Resistance Parameters of Acid-adapted and Unadapted Escherichia coli O157:H7 in Apple Carrot Juice Blends: Effect of Organic Acids and pH. J. Food Protect. (JFP-13-371, accepted Nov. 14, 2013). Awaiting Publication.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Sullivan, E.K., Manns, D., Churey, J.J., Worobo, R.W., Padilla-Zakour, O.I. 2013. Pickled Egg Production: Inactivation Rate of Salmonella, Escherichia coli O157:H7, Listeria monocytogenes and Staphylococcus aureus during Acidification Step. J. Food Protect. 76(11):1846-1853.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Usaga, J., Worobo, R., Padilla-Zakour, O. 2013. Thermal Resistance Parameters for Stationary Phase and Acid-adapted Escherichia coli O157:H7 in Apple and Carrot Juice Blends. Charlotte, NC, USA: 2012 Annual IAFP Meeting. Abstract P2-41.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Acosta, O., Vermeylen, F., Noel, C., Padilla-Zakour, O.I. 2013. Modeling the Effect of Process Conditions on the Accumulated Lethality Values of Thermally Processed Pickled Carrots. Chicago, IL, USA: 2013 IFT Annual Meeting. Abstract 262-04.
- Type:
Websites
Status:
Published
Year Published:
2013
Citation:
http://necfe.foodscience.cals.cornell.edu/acid-and-acidified-foods
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Progress 09/01/11 to 08/31/12
Outputs
OUTPUTS: Continuing our work to develop extension programs to address the needs of small-scale food processors engaged in the manufacture of formulated acid and acidified foods, we added to our training program short videos demonstrating proper procedures to control and to measure the degree of acidity of commercial foods. We also developed a 1-hour module related to federal process filing and state related food safety process reviews. The proposed complete 2-3 day training course is now under review prior to testing and implementation. To fill knowledge gaps we completed challenge studies with pertinent pathogens regarding the safety of cold packed acid and acidified foods (pickle eggs and salad dressings). The results have been presented at the IAFP meeting with several publications in progress in addition to the ones reported in the publications section, including graduate theses as part of professional development. The research studies are currently focused on determining the thermal processing needed to ensure both safety and stability of acid and acidified foods when sound references are not available. An acidified juice made from 80 percent apple and 20 percent carrot was selected as the model system, adjusted to pH of 3.3, 3.5 and 3.7 with malic, acetic and lactic acids to evaluate the effect of acid type on safety and stability for shelf-stable beverages. Pathogenic strains of E. coli O157:H7 were used to determine D and z values at 54-58C. For shelf-stability studies, the same juice was pasteurized by hot-packing (pH 3.3-3.7, malic and acetic acids) at 63, 71 and 77C with 2-min hot hold, into glass or PET bottles. Stability was assessed using total plate counts and yeast and mold counts. We conducted additional studies to evaluate the effect of process conditions (ratio of solids to liquid, brine packing temperature, blanching, and size of solids) on the lethality of thermally processed pickled carrots packaged in glass jars. The 50/50 water to vinegar brine temperature was set at 25 or 75C, with blanching or no blanching prior to filling, ratio of solids to liquid at 35/65 or 65/35, and size of carrot spears (length of 7 cm, average diameter of 1.25 to 1.5 cm, average weight of 9 to 12 g). The prepared jars were placed in a hot water bath to temper the glass and were then transferred to a kettle filled with boiling water. Individual jars were removed from the kettle when the internal temperature of the cold spot (as recorded by a thermocouple inserted in the center of the middle carrot) reached the designated temperature from 60 to 93C, at equally spaced intervals. The accumulated lethality values for temperatures over 60C were calculated for each jar in every trial. The results of these studies will be presented at professional meetings in 2013 and incorporated into the extension guidelines. PARTICIPANTS: Participants (including professional development) Dr. Olga Padilla-Zakour, Cornell University; Dr. Al Bushway, University of Maine; Dr. Beth Calder, University of Maine; Herbert Cooley, technician, Cornell University; Elizabeth Sullivan, graduate student and extension support specialist, Cornell University; two graduate students from Cornell University; two graduate students from University of Maine Collaborators: New York State Department of Agriculture and Markets; Maine Department of Agriculture, Food & Rural Resources; Stonewall Kitchen from Maine; Cooperative Extension/Food Safety from University of Connecticut; Beth's Farm Kitchen from NY; Vermont Food Venture Center; Franklin County Community Development Corporation Greenfield Kitchen, from MA TARGET AUDIENCES: Small-scale food processors, entrepreneurs, farm-based producers, restaurateurs, federal and state food inspectors, extension educators, food safety specialists. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The new training modules were well evaluated with very specific comments to incorporate more details in both, the short videos and the process filing instructions and explanations. We are updating the training materials to fulfill these expectations. From the studies to assess the D and z values of acidified beverages, it was determined that the highest D-value was found when the pH was adjusted to 3.7 with malic acid, at 6 min at 54C. Additional data analysis and validation studies are being conducted to finalize the trials. The on-going hot-packing studies also indicated that malic acid adjusted juices required higher temperatures to achieve shelf-stability, even at low pH values. Shelf-stability was not possible if the hot-pack temperature was less than 77C if a 2 min hot-hold is used, which represents a typical holding time for fast filling lines. The thermal processing trials examining the effects of ratio of solids to liquid, brine temperature, and blanching determined that the interaction between ratio of solids to liquid and brine temperature is highly significant. The highest accumulated lethality was obtained in the treatment with 35/65 ratio of solids to liquid and brine temperature of 75C, while the lowest accumulated lethality in the treatment with 65/35 ratio of solids to liquid and brine temperature of 25C, regardless of blanching. The studies examining the conditions of size of carrot spears, brine temperature, and blanching determined that the size the spears and brine temperature were highly significant. In order to achieve a safe and stable pickled product under the conditions studied, based on final product pH (ranging from 3.9 to 4.4), boiling minimum times of 3 to 15 minutes will be needed for 8 oz jars. Additional trials with different jar geometry and particle size are being conducted. As the project completes the research studies, all findings are being incorporated into science-based, practical guidelines and training materials that will help processors, regulators and food safety extension specialists to ensure the safety and stability of acid and acidified foods.
Publications
- Acosta, O., Sullivan, E.K., Gao, X. and Padilla-Zakour, O.I. 2012. Pickled egg production: effect of brine acetic acid concentration, brine fill temperature, and post-packing temperature on acidification rate. IAFP Annual Meeting. Abstract 2018. https://iafp.confex.com/iafp.2012/webprogram/Paper2018.html.
- Siricururatana, P., Iyer, M.M., Manns, D.C., Churey, J.J., Worobo, R.W. and Padilla-Zakour, O.I. 2012. Shelf-life evaluation of natural antimicrobials for Concord and Niagara grape juices. J. Food Prot.(in press).
- Padilla-Zakour, O.I.,Sullivan, E.K. and Worobo, R.W. 2012. Juices and functional drinks, Chapter 9. In Y. Zhao (ed.), Production of Specialty Foods: Processing Technology, Quality,and Safety. Taylor and Francis. Dallas, TX, p. 239-271.
- Sullivan, E.K., Manns, D.C., Churey, J.J., Worobo, R.W. and Padilla-Zakour, O.I. 2012. Pickled egg production: inactivation rate of Salmonella, Escherichia coli O157:H7, Listeria monocytogenes and Staphylococcus aureus during acidification step. IAFP Annual Meeting. Abstract 2036. https://iafp.confex.com/iafp.2012/webprogram/Paper2036.html.
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Progress 09/01/10 to 08/31/11
Outputs
OUTPUTS: In the second year of the project we worked on designing appropriate extension and outreach programs to address the food safety needs of small-scale food processors engaged in acidified and acid foods production. Two workshops were conducted to test the effectiveness of the materials developed, which included hands-on demonstration of small-scale/artisanal production of a shelf-stable acidified food, and proper procedures to measure and record critical factors such as equilibrated pH, hot-fill temperature, vacuum and container closure integrity. Current FDA guidelines for acidified foods production have been incorporated into the training materials. Additional information from the Food Safety Modernization Act will be added to meet the new requirements. In addition, we have concluded several challenge studies to determine the effect of acidifying agents and pH with and without preservatives on the safety of cold-filled (no thermal processing at or after filling), shelf-stable pickled eggs, cranberry ginger dressing and roasted garlic dressing. The challenges studies were conducted at room temperature for each pathogen. Three strains of the pertinent pathogens Salmonella, Listeria monocytogenes, and Escherichia coli O157:H7, inoculated at either 5-log CFU/g (high level) or 2-log CFU/g (low level), at pH of 3.9 and 3.3 were used for the dressings. For the pickled eggs, the challenge studies were conducted at pH 4.4 and 4.0 with and without sodium benzoate at 0.05% as preservative, inoculated with 6 strains each of Salmonella, L. monocytogenes, E. coli O157:H7 and S. aureus. In addition, a comprehensive acidification study was conducted to evaluate the effect of brine concentration (acetic acid concentrations of 2.5, 5 and 7.5%) brine fill temperature (ambient temperature and 185F), thermal processing (boiling water bath) and storage temperature (refrigeration and room temperature) on time required to achieve egg yolk pH of 4.6 and to reach the final equilibrated pH value. Additional challenge studies are being conducted on minimally processed fig and strawberry commercial dressings, and in carrot/apple juice (pH 3.3-3.7). Completed studies are now in manuscript format for submission to peer reviewed journals, which will facilitate the dissemination and implementation of findings. PARTICIPANTS: Participants (including professional development) Dr. Olga Padilla-Zakour, Cornell University; Dr. Al Bushway, University of Maine; Dr. Beth Calder, University of Maine; Herbert Cooley, technician, Cornell University; Elizabeth Sullivan, graduate student and extension support specialist, Cornell University; two graduate students from Cornell University; two graduate students from University of Maine Collaborators: New York State Department of Agriculture and Markets; Maine Department of Agriculture, Food & Rural Resources; Stonewall Kitchen from Maine; Cooperative Extension/Food Safety from University of Connecticut; Beth's Farm Kitchen from NY; Vermont Food Venture Center; Franklin County Community Development Corporation Greenfield Kitchen, from MA TARGET AUDIENCES: Small-scale food processors, entrepreneurs, farm-based producers, restaurateurs, federal and state food inspectors, extension educators, food safety specialists. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The evaluations of the workshops conducted showed that small-scale processors were very satisfied with the program (average of 4.9 out of 5 = very satisfied), 100% reporting the program met their expectations, and that the knowledge gain increased from 2.2 to 4.5 (1= none/5=full understanding) after the training. Visual aids and demonstrations were cited as key elements to facilitate the learning process. The feedback received will be incorporated into the final training program that is being developed for further testing with a larger group of processors. The results from the challenge studies conducted on the two dressings showed important differences due to the pathogen, level of inoculum and pH. Of the three pathogens tested in non-thermally processed, shelf-stable dressings, E. coli O157:H7 had the greatest survival at both pH 3.3 and 3.9. The three pathogens persisted in the minimally processed salad dressings for varying lengths of time, but did not actually grow in either salad dressing at pH 3.3 or 3.9 and eventually all pathogens died off in samples within 10 days. E. coli O157:H7 survived the longest (up to ten days) in the cranberry ginger dressing at pH 3.9. Injured or sub-lethal cells were not detected from spread plating, and were not recovered from enrichment of E. coli O157:H7. Salmonella did not survive more than 3 days. L. monocytogenes was not detected after 7 days. L. monocytogenes resulted in the highest number of positive enrichments. Injured cells not detected from spread plating were recovered in the higher pH environment of the enrichment broth. The Salmonella trial only resulted in two samples being recovered in enrichment broth. E .coli O157:H7 was the least affected by the acidic condition of the dressings, which indicates that E. coli O157:H7 is the largest food safety threat to minimally processed dressings. The pickled eggs studies confirmed that refrigerated storage slowed the rate of acetic acid penetration. Egg pH was taken at five points within the egg, total yolk, and total egg, until the pickled egg system equilibrated. Eggs stored at room temperature with either room temperature brine or hot brine took two days for the pH at the center of the yolk to fall below 4.6. There was no significant effect (p≤ 0.05) of sodium benzoate on acid penetration. For the challenge study, eggs were refrigerated until the pH at the center of the yolk reached 4.6, corresponding to 5 and 8 days for 5% and 2.5% acetic acid brine concentrations. Both acetic acid brine concentrations were adequate to kill Salmonella, E. coli O157:H7, L. monocytogenes, and S. aureus; within 7 days for 5% brines and within 14 days for 2.5% brines. Egg yolk pH is the best indicator of proper acidification compared to ground whole egg to ensure the safety of pickled eggs. The findings from these studies will provide processors, regulators and food safety extension experts, science-based guidelines to improve the safety of acid and acidified foods.
Publications
- No publications reported this period
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Progress 09/01/09 to 08/31/10
Outputs
OUTPUTS: For the first year of the project we focused on key aspects of the safe formulation and processing of acid and acidified foods and on assessing the training needs of farm producers, small-scale processors and entrepreneurs. We conducted a thorough literature review to determine knowledge gaps and scientific status of formulation and processing parameters that are being used to determine critical control points for safe manufacture of acid and acidified foods. We set-up an Advisory Group to provide continuous advice to the investigators for the duration of the project. We designed and tested an Initial Knowledge Survey (with 67 items) that contained topics covering microbiology; sanitation and personal hygiene; acid and acidified foods terminology; measurement of pH, temperature and water activity; processing and safety; food containers and closures; records and record keeping; and regulations, registration and schedule process filing. We visited several small-scale processors and shared-use/co-packing facilities in New York and Maine to determine processing challenges and overall needs. We recruited five graduate students to participate in the applied research part of the grant, focused on dressings/marinades and pickled products that are cold filled and therefore do not receive a pasteurization step after packing. We also set-up the website structure to accommodate the information being produced to support the small-scale food processors utilizing Cornell's Northeast Center for Food Entrepreneurship website. We began the development of teaching materials and processing forms, which will be posted in the website after peer review and after evaluation by intended audience participants. PARTICIPANTS: Dr. Olga Padilla-Zakour, Cornell University; Dr. Al Bushway, University of Maine; Dr. Beth Calder, University of Maine; Herbert Cooley, technician, Cornell University; Elizabeth Sullivan, graduate student and extension support specialist, Cornell University; two graduate students from Cornell University; two graduate students from University of Maine Collaborators: New York State Department of Agriculture and Markets; Maine Department of Agriculture, Food & Rural Resources; Stonewall Kitchen from Maine; Cooperative Extension/Food Safety from University of Connecticut; Beth's Farm Kitchen from NY; Vermont Food Venture Center; Franklin County Community Development Corporation Greenfield Kitchen, from MA TARGET AUDIENCES: Small-scale food processors, entrepreneurs, farm-based producers, restaurateurs, federal and state food inspectors, extension educators, food safety specialists. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The Advisory Group (AG) has been formed with eight members representing one federal and two state regulatory agencies, two co-packing/shared-use facilities for small-scale production, two processors and members of specialty foods organizations, and one additional food safety extension program (Connecticut), all from the Northeast region. The teaching materials and the processing forms already developed are being evaluated by the AG for improvements and will be uploaded in the website as soon as the changes are finalized. The initial knowledge survey was administered first to twenty participants representing medium, small, and micro-sized food processors from a range of locations with a variety of formulated acid and acidified products. The results indicated the areas of immediate training needs in the following inverse order of familiarity: records and recordkeeping (84 percent reported slightly/not very familiar); food containers and closures (76 percent), regulations, registration and schedule process filing (73 percent); processing and safety (69 percent), acidified and formulated acid foods (66 percent); measurement of pH, temperature, water activity (58 percent); microbiology (49 percent); sanitation and personal hygiene (26 percent). The survey will be administered to a larger group of processors after the AG meets to review initial results. A variety of record keeping forms to comply with the current Acidified Foods Regulations were developed to assess this need with input from local inspectors, including processing records, ingredients/packaging materials, final distribution of packaged foods and training records, which are currently under review by the AG. Specific training materials for establishment registration, process filing and containers/closures adequate for acid and acidified foods were incorporated in a Better Process Control School program, Acidified Foods only version, conducted in November 2010. Feedback from the course evaluation was very positive for the 2 modules tested. From the visits to the processing plants we were able to determine key issues regarding processing challenges and training needs, which are being incorporated into the new training materials. From the literature review conducted, we decided to start the research projects with acid and acidified foods that do not receive a final pasteurization step after filling, as there is a lack of knowledge on the safety and stability of these products under different pH values, type of acid, type of low acid foods in the formulation, and use of preservatives to control spoilage. The research is being conducted by graduate students with four dressings/marinades (pH 3.3-3.8) and pickled eggs (pH 4.5-4.0) as the starting materials. We expect to complete the tests next year and to publish the results in peer-reviewed journals, to facilitate adoption of safety recommendations by processors and regulatory agencies.
Publications
- No publications reported this period
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