Progress 05/01/20 to 12/31/24
Outputs
Target Audience:The target audience has been the food industry that produces blanched vegetables and IQF (frozen) vegetables. The information was also discussed with FDA and the American Frozen Foods Institute (AFFI). The information was also used to train students and was incorporated into lecture series in food microbiology and intervention strategies to control foodborne pathogens. Changes/Problems:One of the challenges that the project team had underestimated was the difficulty in replicating laboratory based steam blanching that could fit within a biosafety cabinet.The amount of steam generated also caused an issue with HEPA filters.The other difficulty was to reliably generate steam with uniform temperature distribution across the steamer and bed depth.Therefore, after several months of trying various methods and equipment and since the industry specifications could not be attained, the data obtained from laboratory scale setting will not correlate with what is actually happening in an industry setting and so the project team decided to abandon this portion to concentrate on water blanching. The project team along with AFFI and Lamb Weston were no successful in securing a pilot scale water blancher that could be used for validation studies.Since the plan was to correlate the data for L. monocytogenes, blancher manufacturers were uncomfortable with the use of pathogens with their systems.The system at Lamb Weston was however too large to fit into IFSH Biocontainment Pilot Plant.Therefore, this portion of the project had to be modified which led to the collaboration with Index BioSystems. What opportunities for training and professional development has the project provided?The project has provided academic training to a graduate student during this period and the project staff acquired new skills in using BioTags, recovery of BioTags, and training on the use of new real-time PCR platform. The project team hopes to, after conducting data analysis and manuscript preparation, use the knowledge to conduct collaborative trials with industry to demonstrate the use of BioTags to correlateL. monocytogenesinactivation and update AFFI blanching guidance documents. How have the results been disseminated to communities of interest?The blanching inactivation data forL. monocytogeneswere shared with FDA and Dr. Gregory Fleishmann has used the information to model the transfer of heat in both steam and water blanching.The outcomes were presented at IFSH Annual Meeting to industry participants and we anticipate the data will be published in collaboration with IFSH team. The modelling information was also presented at FDA Science Forum and at IAFP 2024. Through AFFI assistance, the project team plans to communicate the data with AFFI membership companies at various meetings. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
The US frozen food economy is worth $56 billion with frozen vegetables and potato products accounting for approximately 14.3% market share.These products are blanched using hot water or steam, to inactivate enzymes, expel gases, soften tissues, remove off-flavor or enhance color prior to freezing but blanching was not intended as a microbial inactivation step to inactivate foodborne pathogensnor was it a validated process.Recent recalls, e.g. frozen corn and mixed vegetables in 2023, have heightened the significance of foodborne pathogens in this food category and the need to validate the mitigation strategies used by the industry. Major goals of the project Development of appropriate surrogate(s), correlated to pathogen inactivation, for use in-plant blanching validation studies Correlation of end-point temperature measurement as verification for a 5-log reduction of pathogens Conduct in-plant pilot scale blanching process validation studies to validate surrogate(s), establish critical processing parameters and limits for blanching for seven vegetables (peas, corn, green beans, broccoli, spinach, potatoes, and carrots) Compare and list critical parameters for steam and water blanching for selected vegetables Update AFFI industry best practice guidance document for blanching validation ? The goals of the project were modified because of pilot scale equipment availability and the inability to sufficiently replicate industry process parameters for steam blanching.In consultation with industry groups and AFFI, the number of vegetables were consolidated from seven vegetables to four vegetables.Steam blanching was not conducted because the project team was not able to replicate steam blanching in the laboratory setting with even distribution of steam and temperatures through the steam vessel and therefore decided to use modelling approaches to define steam blanching temperatures in collaboration with scientists from FDA located at Moffett Campus. The project team completed Goal 2 on end-point temperature measurement and verification in collaborations with Index BioSystems through the use of BioTags.This involved the use of short inert DNA sequences, known as BioTags, that were similarly inoculated onto representative vegetables as withListeria monocytogenesand exposed to water blanching process.The level ofL. monocytogenesinactivation was correlated to peroxidase enzyme inactivation and detectability of BioTags by real time PCR. The experiments were performed at IFSH and repeated by Index BioSystems using fresh peas initially washed with 0.03% sodium hypochloride solution to reduce background microflora and further rinsed in fresh sterile water to remove residual sodium hypochloride. The peas were them immersed in a 10 ppm BioTag solution and allowed to dry before hot water blanching at 65ºC for up to 180 s. The project team found BioTags were consistently detected throughout the blanching process and there was a direct correlation (r2=0.83) toL. monocytogenesinactivation over time.At 65ºC, approximately 7 log cfu/g of L. monocytogenes were inactivated on fresh peas and the BioTag Cq values from real-time PCR increased with blanching duration, indicating reduction in BioTag signals with lower recovery ofL. monocytogenes. The experiment was similarly repeated with fresh corn and detection of BioTag signals correlated withL. monocytogenesrecovery.Index BioSystems and IFSH will further collaborate after the end of the grant to show efficacy on carrots and broccoli and correlate the information to data generated by FDA on modelling. The project team is confident the collaboration with Index BioSystems will provide industry with a novel way to verifyL. monocytogenesinactivation by hot water blanching. In collaboration with AFFI, the project team will be working on updating AFFI guidance documents and research manuscripts from the project. The project team will also seek industry funds to validate the use of BioTags in industry settings and have been discussing with Lamb Weston on the use of their pilot plant systems since BioTags are inert and non-infectious.
Publications
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Progress 05/01/23 to 04/30/24
Outputs
Target Audience:Current target audience is the scientific community, trade associations and companies that process blanched vegetables for frozen. The information generated will also interest academia and research community especially those who conduct validation studies and uses scientific information for prediction of microbial inactivation e.g. those who develops and uses predictive models to assess microbial safety.? Changes/Problems:Since Fall 2023, the project team has been trying to secure the use of a pilot scale equipment from a manufacturer so that we can conduct final validation studies using IFSH BioContainment Pilot Plant. A combination of events - availability of the pilot scale blancher and IFSH's effluent decontamination system failure had result in the project not being able to move forward to complete its remaining objectives. Therefore in discussing with the project team and stakeholders, we decided to take the approach of using modelling and also attempt to collect steam blanching inactivation data that was previously abandoned because of equipment reliability. However, if a small set of steam blanching data can be obtained, the project team could use the modelling approach to validate blanching conditions. We believe the modelling approach can still be used as validation of the blanching process and this decision was made in consultation with FDA SME on thermal inactivation. What opportunities for training and professional development has the project provided?The opportunity has brought training opportunities in food microbiology for graduate students especialy training in collecting thermal inactivation kinetics data to establish rate of inactivation. The data obtained also facilitate network and research discussion between FDA and AFFI and industry with further understanding of industry practices and issues. How have the results been disseminated to communities of interest?The data generated in the project was presented in a symposium presented by Dr. Samjay Gummalla during IAFP 2023 in Toronto, Canada.The symposium was entitled "Challenges and Opportunities Navigating Requirements to Ready-To-Eat and Not Ready-to-Eat fro Refrigerated and Frozen Foods".Dr. Sanjay Gummalla, American Frozen Foods Institute, presented on Risk-based Approaches to Ensure Safety Consumption of Frozen Foods.? What do you plan to do during the next reporting period to accomplish the goals?The work on identifying a suitable surrogate will be continuing and will complete the work on BioTags to correlate to enzyme and L. monocytogenes inactivation.We will attempt to collect steam blanching L. monocytogenes inactivation data and similarly correlate to enzyme inactivation and BioTags.
Impacts
What was accomplished under these goals?
The US frozen food economy is worth $56 billion with frozen vegetables and potato products accounting for approximately 14.3% market share.These products are blanched using hot water or steam, to inactivate enzymes, expel gases, soften tissues, remove off-flavor or enhance color prior to freezing but blanching was not intended as a microbial inactivation step to inactivate foodborne pathogensnor was it a validated process.Recent recalls, e.g. frozen corn and mixed vegetables in 2023, have heightened the significance of foodborne pathogens in this food category and the need to validate the mitigation strategies used by the industry. Major objectives of the project Development of appropriate surrogate(s), correlated to pathogen inactivation, for use in-plant blanching validation studies Correlation of end-point temperature measurement as verification for a 5-log reduction of pathogens Conduct in-plant pilot scale blanching process validation studies to validate surrogate(s), establish critical processing parameters and limits for blanching for seven vegetables (peas, corn, green beans, broccoli, spinach, potatoes, and carrots) Compare and list critical parameters for steam and water blanching for selected vegetables Update AFFI industry best practice guidance document for blanching validation The project team has completed the collection of thermal inactivation data forListeria monocytogenesfor four major vegetables (peas, corn, carrot and broccoli). These vegetables are representative vegetables with various geometric shapes, texture and hardness that would represent the seven vegetables originally described in the proposal.The search for an appropriate surrogate that has the similar thermal inactivation kinetics asL. monocytogenesis continuing.The project team has screen various strains ofEnterococcus faecium, commonly used in low moisture food toas a surrogate toSalmonellaspp,Lactococcus plantariumand otherLactococcusstrains andPediococcusstrains that were previously used as surrogates. The project team, now consisting of researchers from FDA, American Frozen Foods Institute (AFFI) and Lamb Weston, will extend the work by examining the heat transfer through vegetables surfaces, initially using broccoli, because of the complex geometry and concerns that buds forming the broccoli surface can create an environment that impede heat transfer.The approach is to measure the temperature during heating using thermocouples placed at two points along the center of the floret stalk near the base and neat the crown where the stalk gives rise to smaller stems leading to the buds.Thermal data collected will be used to model heat transfer for other vegetables based on geometry and can be used for validation and predict the effectiveness of blanching and predictL. monocytogenesinactivation. The project team undertook work to correlate peroxidase enzyme in representative vegetables to the amount ofL. monocytogenesinactivation and found that when peroxidase enzyme was inactivated, no detectableL. monocytogeneswas observed or that there was more than 5 log reduction ofL. monocytogenes.However, the observable visual quality loss of the representative vegetables.It was also difficult to correlate enzyme inactivation based on observed color change from the titration process and the use of optical density did offer some correlation toL. monocytogenesinactivation but equipment availability and user training could possibly be a limiting factor for industry implementation. The enzyme correlation objective has led to the project team searching for new methods to correlate and measure L. monocytogenes that could be implemented in industry. The led to the collaboration with Index BioSystems and the use of BioTags to correlateL. monocytogenes.Index BioSystems uses inert short DNA sequences known as BioTags to trace and verify the identity of foods and BioTags are measurable and inert in foods.BioTags are already been trialled by a number of food companies for tracebility and to track sources of contamination. During IAFP 2024, the project team had a good discussion with Index BioSystems and learn that BioTags responds to heat and could potentially be used to correlateL. monocytogenesinactivation and can also help industry comply with the new FDA Traceability Rule.If BioTags are correlated to enzyme andL. monocytogenesinactivation, BioTags could be spiked into fresh vegetables and measured.The current BioTags quantitation requires real-time PCR and samples could be send to an analytical lab for analysis.Index BioSystems indicated they are working on implementing an on-site reader for industry use. Since Fall 2023, the project team has been trying to secure the use of a pilot scale equipment from a manufacturer so that we can conduct final validation studies using IFSH BioContainment Pilot Plant.IFSH also had facilities issues involving our effluent decontamination system where failure resulting potentially large quantities ofL. monocytogenesinoculated water not being properly treated prior to disposal.The project team had previously scaled back on steam validation because it was difficult to achieve steam pressure and temperature so while waiting for equipment, the graduate student working on the project along with collaborators from Lamb Weston, American Frozen Foods Institute and FDA will attempt to collect steam blanching inactivation data for model construction by FDA scientists during Summer and Fall 2024.We will still be pursuing the large scale blancher but could be low on priority based on time lines.We believe the modelling approach can still be used as validation of the blanching process and this decision was made in consultation with FDA SME on thermal inactivation. In collaboration with AFFI, the project team has been working on collecting and curating industry blanching information on various vegetables and industry practices to prepare and update AFFI blanching guidelines.The project team plan to cascade the information at various meetings including AFFI meeting in later half of 2024 and towards 2025.
Publications
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Progress 05/01/22 to 04/30/23
Outputs
Target Audience:Current target audience is the scientific community, trade associations and companies that process blanched vegetables for frozen. The information generated will also interest academia and research community especially those who conduct validation studies and uses scientific information for prediction of microbial inactivation e.g. those who develops and uses predictive models to assess microbial safety.? Changes/Problems:Accurate and reproducuble thermal inactivation data had been difficult to obtain and repeated experiments were conducted to ensure reproducibility and accuracy of the data. This resulted in a considerable amount of time. Four vegetables were completed and represented vegetables of various geometric sizes, texture and complexicity of the vegetables. With the project team and advisory team, we feel the four currently completed vegetables will adequately represent all seven vegetables and probably the worst case scenerio. We will use the thermal inactivation data along with predictive modelling to complete the remaining three vegetables. This will allow the project team to move to correlation of enzyme inactivation with Listeria inactivation, evaluation of suitable surrogates and other objectives. What opportunities for training and professional development has the project provided?The project had provided the project team to attend IAFP 2022 that resulted in modification of the scientific plan to better obtain thermal inactivation data. The project facilitated the discussion with FDA, AFFI and Lamb Weston including other industry partners. How have the results been disseminated to communities of interest?A poster was presented at IAFP 2022 meeting at Pittsburgh.Discussions with AFFI, FDA and Lamb Weston to review scientific data is on-going in monthly calls. What do you plan to do during the next reporting period to accomplish the goals??The plan is to continue the work on identifying a suitable surrogate, complete thermal characterization of pathogen inactivation, correlate enzyme inactivation to pathogen inactivation, continued discussion for the use of pilot scale blanching equipment.
Impacts
What was accomplished under these goals?
Major objectives of the project Development of appropriate surrogate(s), correlated to pathogen inactivation, for use in-plant blanching validation studies Correlation of end-point temperature measurement as verification for a 5-log reduction of pathogens Conduct in-plant pilot scale blanching process validation studies to validate surrogate(s), establish critical processing parameters and limits for blanching for seven vegetables (peas, corn, green beans, broccoli, spinach, potatoes, and carrots) Compare and list critical parameters for steam and water blanching for selected vegetables Update AFFI industry best practice guidance document for blanching validation The project team has completed the collection of thermal inactivation data forListeria monocytogenesfor four major vegetables (peas, corn, carrot and broccoli). These vegetables are representative vegetables with various geometric shapes, texture and hardness that would represent the seven vegetables originally described in the proposal.The project team found the collection of reliable thermal inactivation data was variable and time consuming with repeated experiments for reproducibility and therefore, the modified approach of using data from the current four vegetables together with thermo-dynamic modelling, in collaboration with FDA, can be used to model heat transfer and blanching characteristics for other vegetables to predict pathogen inactivation. The project team, with collaboration with FDA, American Frozen Foods Institute (AFFI) and Lamb Weston, will extend the work by examining the heat transfer through vegetables surfaces, initially using broccoli, because of the complex geometry and concerns that buds forming the broccoli surface can create an environment that impede heat transfer.The approach is to measure the temperature during heating using thermocouples placed at two points along the center of the floret stalk near the base and neat the crown where the stalk gives rise to smaller stems leading to the buds.The rate of temperature increase during blanching, is simultaneously compared between the two thermocouples and in combination with thermal inactivation data already collected, the information can be used to predict the effectiveness of blanching and predictL. monocytogenesinactivation. The work on correlating end-point temperature measure with enzyme andL. monocytogenesinactivation is on-going.This part of the work is being conducted by a research student who started in Spring 2023 but had to leave the project due to academic load.The work will be continued by another research student in Fall 2023. In Fall 2022, project PD visited Lamb Weston to evaluate industry parameters used in hot water and steam blanching.The project team will use the parameters in a second attempt to design equipment for steam blanching and collect thermal inactivation data forL. monocytogenes. Previous attempts at steam blanching proved challenging due to pressures needed to attained during blanching. We are also using the current information on hot water blanching to translate from lab scale to pilot scale equipment and actively discussing with Lyco Manufacturing and AFFI on the possibility of use a pilot scale blancher that does both hot water and steam blanching to be either on-loan to the project team or used on-site at Lyco Manufacturing location in Columbus, Wisconsin. In collaboration with AFFI, the project team has been working with AFFI on collecting and curating industry blanching information on various vegetables and industry practices to prepare and update AFFI blanching guidelines.The project team plan to cascade the information at various meetings including AFFI meeting in early 2024.
Publications
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Progress 05/01/21 to 04/30/22
Outputs
Target Audience:Current target audience is the scientific community, trade associations and companies that process blanched vegetables for frozen. The informationgenerated will also interest academia and research community especially those who conduct validation studies and uses scientific information for prediction of microbial inactivation e.g. those who develops and uses predictive models to assess microbial safety.? Changes/Problems:No major issues but the project team is keeping a close eye on the time line because of lost productive time during COVID-19 shut down and having to restart all experiments. What opportunities for training and professional development has the project provided?The data generated can be utilized by industry for validation and to assist the American Frozen Food Institute (AFFI) supplement data AFFI has collected and published in their Validation of Blanchers guidance.Similarly, the data generated can be used for validation of blanching workshops or groups conducting validation studies. AFFI has previously conducted various workshops and training sessions for industry professionals in the area of food safety, food processing and packaging and various aspects pertaining to the frozen foods industry. The outcomes developed in the project can be easily assemiliated into AFFI current food safety workshop offerings e.g. Validation of Blanchers workshops and the thermal inactivation data, which is currently lacking, will compliment the workshop and training curriculum. The project team intends to work with FDA scientists to develop predictive modelling to predict heat distribution on various produce items in addition to ComBase activities and to collaborate with computational scientists located within Illinois Tech and with AFFI to utilize machine learning to predict blanching outcomes. A number of graduate students have expressed interest in the project and will work with the project team over the summer 2022 semester and anticipates two graduate students will be working with the project team.? How have the results been disseminated to communities of interest?A poster titled "Screening ofListeria monocytogenesstrains for blanching validation" has been accepted for presentation at IAFP 2022 Annual Meeting in Pittsburgh, PA. Some results from strain selection and blanching outcomes were incorporated into current teaching by the PI in FdSN505 Food Microbiology and also presented in industry based sessions at the Food Safety Summit. What do you plan to do during the next reporting period to accomplish the goals?The research team plans to continue blanching characterization of the remaining six produce items withL. monocytogenes.The analysis of the data will lead to more targeted studies withE.coliO157:H7 andSalmonellaspecies and the screening and characterization of potential surrogates.The identified surrogates will be used in a pilot plant trials in collaboration with blanching equipment company, Lyco Manufacturing and AFFI industry members.
Impacts
What was accomplished under these goals?
The project team was able to design an experimental setup for safe, reliable and robust blanching of inoculated produce without the need of constantly disinfecting the entire water bath after each experimental run.The use of a removable secondary vessel with submersible stirring allows for even distribution of water temperature.At the end of each experimental run, the secondary vessel is removed from water bath and replaced with a new sterile secondary vessel Two produce products (peas and corn) were completed with the new setup and new work on broccoli has started.With each produce item studied, inoculation procedures and recovery procedures were tested to ensure the stability of the inoculum on produce and the ability to reliably recover and detectL. monocytogenescultures from produce.IndividualL. monocytogenesstrains (n=5) were grown using Tryptic Soy Agar with Yeast Extract (TSAYE) with Modified Oxford Medium (MOX) overlay and approximately 7 log CFU/mL were inoculated onto various fresh peas and corn.Blanching was conducted various temperatures (up to 80ºC) and times to obtain inactivation curves and derivation of D- and z- values. L. monocytogenescocktail (L338, L303, L356, L357 and L358) was inoculated into peas (25g) and heat treated with D65ºC, D70ºCand D75ºCat 27.5s, 6.8s and 1.69s respectively and z-value of 8.26ºC.Fresh corn (25g) was similarly inoculated withL. monocytogenescocktail and heat treated.The D65ºC, D70ºCand D75ºCwere 39.4s, 11.0s and 6.22s with a z-value of 11.81ºC.
Publications
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2022
Citation:
Screening of Listeria monocytogenes strains for blanching validation
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Progress 05/01/20 to 04/30/21
Outputs
Target Audience:Current target audience is the scientific community, trade associations and companies that process blanched vegetables for frozen. The informationgenerated will also interest academia and research community especially those who conduct validation studies and uses scientific information for prediction of microbial inactivation e.g. those who develops and uses predictive models to assess microbial safety. Changes/Problems:There was only two major changes - procedures for inoculating vegetables and conducting blanching studies in a contained fashion that minimise contamination to heating equipment. There were a number of inoculation procedures in published literature but, in our hands, we were not able to achieve a high inoculation level that allows for accurate quantification of 5-log reduction. Similarly, blanching studies previously conducted by other researchers used water bath with very limited quantity of produce and blanching was not conducted in a contained fashion and therefore limiting the number of trials that could be conducted before decontamination of heating equipment was needed. We had developed a system similar to a double boiler where large quantites of produce could be blanched at the same time and the vessel used to contain the blanched vegetable can be individually decontaminated prior to next blanching run. What opportunities for training and professional development has the project provided?The data generated can be used for validation of blanching workshops or groups conducting validation studies. AFFI has previously conducted various workshops and training sessions for industry professionals in the area of food safety, food processing and packaging and various aspects pertaining to the frozen foods industry. The outcomes developed in the project can be easily assemiliated into AFFI current food safety workshop offerings e.g. Validation of Blanchers workshops and the thermal inactivation data, which is currently lacking, will compliment the workshop and training curriculum. Also, the data generated could be used by academia who teaches predictive modelling and that students will be exposed to the various data sets and predictive models. The project team believes the generated data will be suitable for contribution to USDA funded ComBase and so the models developed will be made available to the wider scientific audience. There are also othter outreach and professional development could be developed from the generated information and will work with AFFI and other industry companies to develop training materials, information and supplement guidance with scientific data e.g. Validation of Blanchers guidance by AFFI. How have the results been disseminated to communities of interest?The current results have been discussed within the research team, AFFI scientific team and selected industry companies. We believe when mroe data is generated, we will collate the information and disseminate to interested communities. What do you plan to do during the next reporting period to accomplish the goals?The research team plans to use the developed microbial inoculation protocol and blanching protocol to conduct studies with various vegetables after studies conducted with peas and corn are complete. This will allow better comparison of data across the different vegetables. Also, the research team will be working to select and qualify a suitable surrogate for large scale work and to work with industry partners to design the steam blancher protocol and also discuss with equipment manufacturer for possible loan of blanching equipment to conduct pilot scale studies.
Impacts
What was accomplished under these goals?
The initial work started with screening of various outbreak releated Listeria monocytogenes (Lm) strains for thermal inactivation at various temperatures. The goal was to determine which strains of Listeria monocytogenes would be the most robust in thermal inactivation studies and to select strains that would form the final cocktail of Listeria monocytogenes for use in studies using various vegetables. The other objective of the current goals were to established a reproducible and reliable method for blanching vegetables and conduct inoculation studies as recommended by NACMCF. The final cocktail of Lm strains were selected and a reliable method for inoculation of produce items with Lm was also developed. Similarly, the method of blanching vegetables with minimal variation in temperature and blanch time were also established. Studied using this new Lm cocktail was conducted with fresh peas during fresh peas harvesting and the method will be applied to other vegetables as well. The next vegetable will be fresh corn which is the next crop for harvesting. Blanch times and temperatures were also developed in consultation with industry companies and with the American Frozen Food Institute (AFFI). This is to ensure the outcomes of the blanching results will stay relevant to industry conditions. The project team will look into presenting the findings at the next AFFI conference and at various scientific meetings e.g. IAFP.
Publications
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