Progress 08/01/09 to 07/31/11
Outputs
OUTPUTS: There were four activities related to the project: 1) The main activity was to determine the otimal conditions for maximum log reductions of Salmonella by high pressure processing (HPP) in organic, minimally processed peanut butter, 2) sensory testing to compare untreated controls with HPP treated samples for the purpose of consumer acceptability , 3) shelf-life stability testing of HPP processed peanut butter samples as compared HPP treated samples to see if they are more microbiologically stable over time, and 4) analysis of peanut and peanut butter samples by high-throughput DNA sequencing to indicate what populations of natural microflora resides on peanuts and peanut butter. The results of the high pressure processing work was disseminated through a presentation at the annual International Association of Food Protection meeting in 2010. The poster is on display in the Food Science Department and will be available for download from The Food Processing Center website. Two manuscripts are in preparation as a result of this work. PARTICIPANTS: Tara Stiles was an M.S. student who received her degree in Food Science and Techonology in August 2010 for her Thesis on this project, which greatly contributed to her professional development. Jayne Stratton, the PI on the project, was Tara's advisor. Tara was Dr. Stratton's first graduate student and greatly contributed to her professional development as a faculty member and mentor to future students. Steve Stephens (Process Engineer) and Dr. Durwood Smith, (Associate Professor and Co-PI), were involved in planning the resesarch project and a co-authored the poster with Ms. Stiles and Dr. Stratton that was presented at the International Association of Food Protection in 2010. Once Again Nut Butter company collaborated by providing the organic peanut butter for the high pressure, sensory, and shelf life studies. American Pasteurization Company (APC) collaborated by processing samples in their pilot-scale, food-grade facility for the sensory and shelf life studies. APC also provided input on processing conditions used in the study. Dr. Susan Cuppett, professor in the Food Science and Technology Department and Julie Reiling, product developer in The Food Processing Center, conducted the sensory analysis on the peanut butter samples. Dr. Vicki Schlegel in the Food Science Department has assisted by testing for rancidity during the shelf life study. Dr. Dave Rickert, a Co-PI, left The Food Processing Center for a new position before the project was able to start. Food Processing staff Robin Krokstrom (laboratory technician) and Bismarck Martinez (M.S. graduate student) completed the laboratory testing for the shelf life study and assisted in data analysis. Samantha Carter was an undergraduate student that assisted in compiling papers and conducting a literature review in preparation of the manuscript for publication. TARGET AUDIENCES: Target audiences for this work includes food processors, ingredient suppliers, government agencies, and the scientific community. The use of high pressure processing on a food system as challenging as peanut butter (high fat, low moisture) could lead to new applications in food safety on products that have not been previously studied. An effort to reach this audience was made by presenting a poster at the International Association of Food Protection Annual Meeting in August 2010. The poster from this meeting is displayed outside the The Food Science and Technology Department High Pressure Processing facility and will be used to inform students, faculty, and visitors of the potential food safety applications of high pressure processing. It will also be available for download from the Food Processing Center website. Two manuscripts are in preparation: one for the high pressure processing and another for the pyrosequencing. This will reach a wider audience that will include the international scientific community. PROJECT MODIFICATIONS: The initial project was designed to study the effect of high pressure processing on organic, minimally-processed peanut butter. However, early trials showed that high pressure was unable to reduce the level of Salmonella in plain, unaltered peanut butter even at high pressures and long holding times (600 MPa, 30 minutes). It was concluded that the high-fat, low moisture content was having a protective effect and raising the water activity of the peanut butter was necessary to allow for the reduction of Salmonella. Therefore, peanut butter was formulated with minimal ingredients into a palatable sauce that raised the water activity to levels that would allow high pressure processing to be effective in reducing Salmonella. This change did result in greater than 5-log reductions using certain HPP parameters. Therefore, it is possible that the results of this work can be transferred to new, innovative products that use peanut butter as an ingredient, thus increasing not only the safety of the product, but the sensory attributes as well. Also, a delay in receiving the award by several months (October instead of July) caused a delay in starting the project, and pushed back the start date of the shelf life study. In more recent stages of the project, the pyrosequencing facility was down for a month due to faulty kits which caused a delay in receiving the data from this part of the study. However, the facility was able to process all of the samples a few months later and send the finalized data set for analysis.
Impacts
In study 1, a pressure of 600 MPa with a hold time of 7 minutes was found to be the optimal condition to achieve a five log reduction of Salmonella in a 33% peanut butter sauce that was tested using a Stansted ISO Food Lab System. Although the hold time was longer than desirable, it is within the parameters used by industry. Parameters were also provided for products containing different percentages of peanut butter. As the percentage of peanut butter in the samples decreased, higher log reductions were achieved, indicating that the peanut butter had a protective effect on the organism. For example, a 15% peanut butter sauce required 1 minute at 600 MPa while a 20% peanut butter product required a hold time of 5 minutes to eliminate Salmonella. The results from the high pressure studies indicated that raising the water activity of peanut butter supports the use of the HPP process as an intervention to reduce the risk of Salmonella. This has the potential impact of increasing the safety of many different products that use peanut butter as an ingredient, such as sauces, confections, and Asian style marinades and dressings. This research was presented at the 2010 International Association for Food Protection Annual meeting. In study 2, industry collaborators at the American Pasteurization Company processed food grade samples for the sensory panels, and Once Again Nut Butter company provided the organic peanut butter. The results from the sensory panels indicated that the HPP processed samples had a more desirable color and texture than the control samples, thus signifying that the process would actually enhance the desirability of final product to the consumer. In study 3 the HPP processed samples performed much better in the shelf life than the untreated control samples. The control samples had over 1 million cfu/g Aerobic Plate Count by month 4 while the treated samples had less than 500 cfu/g. In study 4, the community and population of bacteria associated with peanut butter were evaluated using pyrosequencing of 16S rRNA gene amplicons. A diverse community was detected with several phyla and genera represented. The total number of reads per sample ranged from approximately 6,500 to 40,700. The classified sequences from the samples were assigned to 14 different phyla with the largest number of reads belonging to Proteobacteria and Firmicutes. Within the Proteobacteria, sequences belonging to the class gammaproteobacteria - particularly the genus Acinetobacter, Pseudomonas, and Citrobacter were the most numerous. The highest number of sequences within the class alphaproteobacteria belonged to the genus Sphingomonas. Within the Firmicutes, the class Bacilli was the most represented, with the predominant organisms from the genus Leuconostoc, Weissella, and Lactococcus. Pyrosequencing allowed a broader description of the bacterial composition and diversity of the peanut butter samples than possible using traditional culture-based detection and will be a powerful tool to help ensure the future safety and quality of both organic and non-organic peanut butter.
Publications
- No publications reported this period
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Progress 08/01/09 to 07/31/10
Outputs
OUTPUTS: There are four activities related to the project. Two primary activities were completed and two more are in the process of completion. First, the high pressure processing (HPP) studies on reducing Salmonella in organic, minimally processed peanut butter have been completed. This involved running several replications of inoculated samples under varying HPP conditions of time and pressure, and the otimal conditions for maximum log reductions were determined. Second, independent samples were processed by the recommended parameters found in the first study in a food-grade, pilot scale HPP system. Some of these samples were then used to run and complete a sensory panel comparing untreated controls with HPP treated samples. Third, a group of samples produced in the food-grade facility were subjected to a shelf-life study. The shelf life study of HPP processed peanut butter samples is two months into a six month long study, and will show if HPP treated samples are more microbiologically stable over time. Fourth, high-throughput DNA sequencing on peanut and peanut butter samples was just completed by the University of Nebraska-Lincoln Core for Applied Genomics and Ecology (UNL-CAGE), and data analysis is pending. This analysis will indicate what populations of natural microflora resides on on peanuts and peanut butter. Dissemination of the results of the HPP study from the first activity were presented in a poster at the International Association of Food Protection meeting in August 2010. PARTICIPANTS: Tara Stiles was a master's student who received her M.S. degree in Food Science and Techonology in August 2010 for her Thesis on this project, which greatly contributed to her professional development. Jayne Stratton, a co-PI on the project, was Tara's advisor. Tara was Dr. Stratton's first graduate student and greatly contributed to her professional development as a faculty member and mentor to future students. Steve Stephens (Process Engineer) and Dr. Durwood Smith, (Associate Professor and Co-PI), were involved in planning the resesarch project and a co-authored the poster with Ms. Stiles and Dr. Stratton that was presented at the International Association of Food Protection in 2010. Once Again Nut Butter company collaborated by providing the organic peanut butter for the high pressure, sensory, and shelf life studies. American Pasteurization Company (APC) collaborated by processing samples in their pilot-scale, food-grade facility for the sensory and shelf life studies. APC also provided input on processing conditions used in the study. Dr. Susan Cuppett of the Food Science and Technology Department conducted the sensory analysis on the peanut butter samples with the help of Julie Reiling, a product developer in The Food Processing Center. Dr. Vicki Schlegel in the Food Science Department has assisted by testing for rancidity during the shelf life study. Dr. Dave Rickert, a Co-PI, left The Food Processing Center for a new position before the project was able to start. TARGET AUDIENCES: Target audiences for this work includes food processors, ingredient suppliers, government agencies, and the scientific community. The use of high pressure processing on a food system as challenging as peanut butter (high fat, low moisture) could lead to new applications in food safety on products that have not been previously studied. An effort to reach this audience was made by presenting a poster at the International Association of Food Protection Annual Meeting in August 2010. The poster from this meeting is displayed in The Food Science and Technology Department and will be used to inform students, faculty, and visitors of the potential food safety applications of high pressure processing. PROJECT MODIFICATIONS: The initial project was designed to study the effect of high pressure processing on organic, minimally-processed peanut butter. However, early trials showed that high pressure was unable to reduce the level of Salmonella in plain, unaltered peanut butter even at high pressures and long holding times (600 MPa, 30 minutes). It was concluded that the high-fat, low moisture content was having a protective effect and raising the water activity of the peanut butter was necessary to allow for the reduction of Salmonella. Therefore, peanut butter was formulated with minimal ingredients into a palatable sauce that raised the water activity to levels that would allow high pressure processing to be effective in reducing Salmonella. This change did result in greater than 5-log reductions using certain HPP parameters. Also, a delay in receiving the award by several months (October instead of July) caused a delay in starting the project, and pushed back the start date of the shelf life study. In more recent stages of the project, the pyrosequencing facility was down for a month due to faulty kits which caused a delay in receiving the data from this part of the study.
Impacts
In the first study, a pressure of 600 MPa with a hold time of 7 minutes was found to be the best conditions for the reduction of Salmonella in the product that was tested using a Stansted ISO Food Lab System, and were within the parameters used by industry. The results from the high pressure studies indicated that raising the water activity of peanut butter supports the use of the HPP process as an intervention to reduce the risk of Salmonella, but is not effective on peanut butter alone. This has the potential impact of increasing the safety of many different products that use peanut butter as an ingredient. Equipment and laboratory resources, such as the HPP Processing Facility in the Food Science and Technology Department (FDST) and the BL-II microbiology lab at The Food Processing Center allowed for the evaluation of this project with minimal costs or waiting time. In the second study, outside collaborators at the American Pasteurization Company provided pilot scale processing of samples for the sensory panels, and Once Again Nut Butter company provided the peanut butter for all the studies. Working with these companies allowed project managers to directly interact with manufacturers, therefore real-world applications and impacts were considered. Internal collaboration with the FDST Sensory Laboratory found that HPP does not adversly affect the sensory characteristics of peanut butter, including taste, color, and oil separation. In the third study, observations at two months indicate that the HPP treated samples are more microbiologically stable than the controls, which are already showing microbial degradation. In the fourth study, the UNL pyrosequencing facility's data will enable researchers to observe the total population of microorganims that reside on peanuts and peanut butter and could lead to a new understanding of the naturally-occuring flora. It is important to know what potential spoilage or pathogenic organisms may be present in a low-moisture food product that may not always undergo a kill step.
Publications
- No publications reported this period
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