Progress 07/01/22 to 06/30/23
Outputs
Target Audience:Food industries manufacturing low moisture foods and food ingredients, pasteurization equipment manufacturers for low-moisture foods Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? One doctoral student gained hands-on experience in the interdisciplinary fields of food engineering, microbiology, and chemistry. The collaboration with food industries through this project enabled the student to develop soft skills and build network with industry folks. Immediately after graduation, the doctoral student got a R&D scientist position in a global food company in the area of food safety. One master student was provided training on the operation of ozone gaseous system and bacterial enumeration of gas treated sample. Immediately after graduation, she was accepted into a doctoral program at another land-grant institution. Two graduate students were trained in conducting quality and byproduct analysis of gas treated low moisture foods. Two undergraduate students were trained in microbiological techniques, including the preparation of media, diluents, and operation of a biosafety cabinet. One graduate student was trained in analyzing the flow of gas through a bed of dried basil leaves and black peppercorn using micro-CT scanning of food samples. How have the results been disseminated to communities of interest?The results have been published in peer-reveiwed journals and presented at various international conferences. We also interacted with few companies including a large global food industry, who is the manufacturer of spices. What do you plan to do during the next reporting period to accomplish the goals?Obj. 1. The data collection for ozone inactivation of Salmonella in dried basil leaves, black peppercorns, chia seeds and walnuts is complete. Manuscripts for the same is under progress and will be published. The microbial inactivation data has been collected for vaporized hydrogen peroxide treatment of dried basil leaves, chia seeds and walnuts and is anticipated to be published by next reporting period. Obj. 3. The prepared surface mesh will be imported into a finite-element simulation software to generate a volumetric mesh, create a 3D geometry, and simulate the airflow inside the basil bed. To obtain the velocity distribution and pressure field, the Navier-Stokes equation, along with the continuity equation, will be applied. Having the velocity and pressure profiles in hand, dead-end zones and poorly connected regions where the gas flow cannot reach sufficiency can be identified. Obj. 4. In the next reporting period, the quality analysis for ozone treated dried basil leaves, black peppercorns, chia seeds and walnuts (fatty acid profile, residue/byproducts analysis) will be completed and published.
Impacts
What was accomplished under these goals?
Impact statement: Dr. Subbiah's team evaluated the efficacy of O3 gas against Salmonella in dried basil leaves, black peppercorns, chia seeds and walnuts. Ozone was found to be effective at high relative humidity conditions (90%) resulted in maximum log CFU/g reductions of 5.0 ± 0.4 for basil, 2.5 ± 0.2 for black pepper, 1.1 ± 0.1 for chia seeds, and 1.5 ± 0.2 for walnuts. Post-treatment mild heating at 40ºC for 4 h further significantly inactivated Salmonella by 1-1.5 log CFU/g for black pepper and basil, but not for walnuts and chia seeds. Dr. Ponder's lab evaluated the effect of different media and supplements on the recovery of multiple strains of S. enterica and Enterococcus faecium NRRL B2354, from chlorine dioxide and hydrogen peroxide treated low moisture foods (LMF). It was found that non-selective media provided better recovery of bacteria from treated samples as compared to selective media. Dr. Irmak provided guidance in the development of protocols for the quality analysis of ozone treated black peppercorns, chia seeds, walnuts and dried basil leaves. There was no significant impact of gaseous ozone treatment on color, antioxidants, and total phenolics of the four LMFs. However, 5 h ozone treatment caused significant loss in a few minor volatile compounds of dried basil leaves, and black peppercorn and increased the primary and secondary oxidation products in walnuts. To aid in the scale up of gaseous technologies, Dr. Takhar's lab worked on X-ray micro-computed tomography (X-ray micro-CT) imaging technique to visualize the dried basil leaves. Following the image acquisition, the reconstructed data was quantified to characterize the pore structure of the basil bed. Objective specific report: Obj. 1a. Design and fabricate precise treatment systems. The experimental apparatus to fluidize the black peppercorn in vaporized hydrogen peroxide was custom built in the lab from polyvinyl chloride pipes. The fluidized gas chamber was connected to the gas generator procured from Bioquell to control the gas concentration, temperature, air flow rate and exposure time precisely. In addition to the fluidized chamber, a static treatment chamber was designed to assess the inactivation efficacy of vaporized hydrogen peroxide for other low moisture foods. Ozone gas generator and analyzer was successfully set up and optimized in the lab in collaboration with Ozone Solutions to monitor and achieve stable ozone concentration in the treatment chamber. Obj. 1b. Develop gaseous inactivation kinetic models. Salmonella and E. faecium inoculated samples (dried basil leaves, black peppercorn, chia seeds, and walnuts) were treated simultaneously with gaseous ozone concentration of 900-930 ppm and RH of 90% over treatment time of 1-5 h and bacterial log reductions were fitted into primary models. The log-linear model therefore fitted the inactivation data better due to lower RMSE and AICc values in dried basil leaves, whereas non-linear inactivation was explained better by Weibull model in black peppercorn, chia seeds, and walnuts. With increase in treatment time from 1-5 h, the experimental Salmonella log reductions increased significantly from 1.73 to 5.29 log CFU/g for dried basil leaves and from 0.46 to 2.47 log CFU/g for black peppercorn (P<0.05). For chia seeds and walnuts, the maximum Salmonella reduction of 1.08 ± 0.03 and 1.52 ± 0.19 log CFU/g was achieved at 5 h treatment, which was not significantly different from the 1 h treatment (P<0.05). The effect of %RH on the antimicrobial efficacy of ozone was evaluated in dried basil leaves. Dried basil leaves were treated with gaseous ozone concentrations of 900-930 ppm at different RH levels of 70, 80, and 90% for 1-5 h. With the increase in RH from 70 to 90%, Salmonella log reduction increased significantly from 1.2 ± 0.2 to 4.9 ± 0.6 over 5 h exposure time (P<0.05). The substantial impact of RH on the bactericidal efficacy of ozone may be attributed to the formation of highly reactive hydroxyl radicals resulting from the reaction of ozone molecules and humidity. The D-value decreased significantly from 4.4 to 1 h for Salmonella and from 3.4 to 1.3 h for E. faecium (P<0.05) with an increase in RH from 70 to 90%. Obj. 2b. EvaluateEnterococcus faecium as a surrogate. Identifying a suitable surrogate for Salmonella is necessary to assist the food industries in conducting an in-plant validation study related to gaseous inactivation technologies. For vaporized hydrogen peroxide treatment of dried basil leaves and black peppercorns, E. faecium was shown to have higher reduction compared to Salmonella at all treatment conditions tested. Therefore, it can be concluded that it is not a suitable surrogate for Salmonella. In the case of ozone treatments, E. faecium demonstrated its suitability as a surrogate for Salmonella in dried basil leaves at conditions that gave >2.5 log reduction of Salmonella. E. faecium was not a good surrogate for chia seeds, black peppercorns, and walnuts rendering it unsuitable for in-plant validation. Obj. 3. Develop and validate a multiscale modeling framework. The X-ray micro-computed tomography (X-ray micro-CT) imaging technique was utilized to visualize the dried basil leaves. Initially, the basil leaves were placed in a Petri dish and scanned using a high-resolution X-ray micro-CT scanner (Rigaku CTLab HX) available in the Beckman Imaging Center at the University of Illinois at Urbana-Champaign. The collected data were then reconstructed into a series of 16-bit 2D images in TIFF format using the XMReconstructor software. The scanning process provided 1983 image slices with a voxel size of 10.5 μm×10.5 μm×10.5 μm and a total physical size of 30.1 mm × 14.1 mm × 20.8 mm. Following the image acquisition, the reconstructed data were imported, processed, and visualized using the 3D examination software Avizo. The purpose was to quantify and characterize the pore structure of the basil bed. In this stage, the original CT scanning images were subjected to various image processing steps, such as sub-volume selection, noise removal, and subgrouping procedure. As a result, a 3D binary image with a distinct pore and solid spaces was generated. The analysis indicated that pore space occupied 69 percent of the Petri dish content while the portion of solid space (basil leaves) was only 31 percent. After visualizing the sample and calculating its porosity, the image was further processed to prepare it for the CFD simulation objective. A surface mesh suitable for simulation was generated after resolving mesh issues, such as mesh intersection, closedness, orientation, and aspect ratio. Obj. 4. Evaluate food quality attributes. Quality analysis of chia seeds treated with chlorine dioxide either alone or followed by mild heating were completed. The water activity in chia seeds samples was significantly higher (p< 0.05) in ClO2 treated samples as compared to the control samples. The b* value representing the yellow to blue color, was significantly higher (p < 0.05) in chia seeds treated with ClO2 at 5 mg/L concentration under 80% RH for 2 h (6.03 ± 0.06) compared to the control samples (4.97 ± 0.51). The peroxide value for chia seeds significantly increased (p< 0.05) by more than 10 folds after exposure to ClO2 treatment compared to the untreated samples (8.34 ± 10.45). Chia seeds treated with ClO2 at 3 and 5 mg/L concentrations were analyzed for residues over different storage periods. Chlorate residues were significantly higher in the 5 mg/L treatment initially but showed no changes over time. Chloride residues differed significantly after 1 day of storage in the 5 mg/L treatment. Chlorite residues were mostly undetectable, except in one treatment after 1 and 3 days of storage, but all values remained below regulatory limits.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
Wason, S., J. Subbiah. 2023. Gaseous chlorine dioxide for inactivating Salmonella enterica and Enterococcus faecium NRRL B-2354 on chia seeds. Food Control, 150, 109736. https://doi.org/10.1016/j.foodcont.2023.109736
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
2. Wei, X., T. Verma, S. Irmak, J. Subbiah. 2023. Effect of storage on microbial reductions after gaseous chlorine dioxide treatment of black peppercorns, cumin seeds, and dried basil leaves. Food Control, 148, 109627. https://doi.org/10.1016/j.foodcont.2023.109627
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
5. Summers, E., S. Wason, J. Subbiah, J., R. Villa-Rojas. 2023. Inactivation of Salmonella enterica in black peppercorn by fluidization with hydrogen peroxide vapor. Frontiers in Food Science and Technology, 3, 1119715. https://doi.org/10.3389/frfst.2023.1119715
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2023
Citation:
Wason, S. (2023). Radiofrequency and Gaseous Technologies for Enhancing the Microbiological Safety of Low Moisture Food Ingredients. Graduate Theses and Dissertations Retrieved from https://scholarworks.uark.edu/etd/4940
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Wason, S. and Subbiah, J. (2023). Optimization of Vaporized Hydrogen Peroxide Inactivation of Salmonella in Dried Basil Leaves by Central Composite Design. International Association for Food Protection.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Khattra, A., Wason, S., Gowda, N., Subbiah, J., Acuff, J. (2023). Gaseous Ozone to Improve the Microbial Safety of Spices and Nuts. International Association for Food Protection.
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2023
Citation:
Khattra, A. (2023). Gaseous ozone to improve the microbial safety of spices and nuts. (Masters Thesis, University of Arkansas).
|
Progress 07/01/21 to 06/30/22
Outputs
Target Audience:Food industries manufacturing low moisture foods and food ingredients, pasteurization equipment manufacturers for low-moisture foods Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? One doctoral student gained hands-on experience in the interdisciplinary fields of food engineering, microbiology, and chemistry. The collaboration with food industries through this project enabled the student to develop soft skills and build network with industry folks. Four master's students were trained on microbiological techniques including operation of biosafety cabinet, plating and enumeration techniques. One master student was provided training on the operation of gaseous system and handling of treated sample. Two undergraduate students were trained on the microbiological techniques including preparation of media, diluents, and operation of biosafety cabinet. One masters student was trained on basics of different recovery media and their formulations to evaluate the best media and diluent for the study. One graduate student was guided on how breakdown products of ClO2 in black peppercorns, cumin seeds, and dried basil leaves could be determined. The student was trained on sample preparation for determination of the ion breakdown products (chlorate, chlorite and chloride ions) by ion chromatography. One graduate student was provided training in microCT scanning of food samples, sample preparation for loading on microCT machine, freeze drying, micro CT setting parameters and image interpretation. How have the results been disseminated to communities of interest?We have interacted with equipment manufacturers of gaseous technologies and shared the results. In addition, we presented results in peer-reviewed publications and scientific meetings. What do you plan to do during the next reporting period to accomplish the goals?Obj. 1. The data collection for chlorine dioxide inactivation of Salmonella in chia seeds and walnuts is complete. Manuscripts for the same will be prepared and published. The microbial inactivation data has been collected for vaporized hydrogen peroxide treatment of dried basil leaves and black peppercorns and is anticipated to be published by next reporting period. For the ozone system, a controller for precise and stable management of process parameters such as gas concentration, relative humidity and temperature will be optimized and evaluated for its microbial inactivation efficacy. Preliminary experiments with ozone gas inactivation of Salmonella will be conducted in black peppercorns and dried basil leaves thereafter. Obj. 2. Data collection has been complete. Manuscript will be submitted documenting the decreased recovery of Salmonella from chlorine dioxide and hydrogen peroxide treated spices when using highly selective media. Obj. 3. MicroCT images for a low moisture foods will be simplified, segmented, and a pore network model will be developed. The fluid mechanics equations will be solved for the reconstructed geometry using computational fluid mechanics techniques to determine the flow patterns of sanitizer fluid through the channels. This will help to determine the accessibility of channels, pores and low flow regions where the microbes could grow. Obj. 4. In the next reporting period, we will perform quality analysis for ClO2 and H2O2 treated chia seeds and walnuts (fatty acid profile, residue/byproducts analysis). We will perform quality analysis for H2O2 treated dried basil leaves (volatiles and H2O2 residue analysis). Ozone-treated samples will be analyzed.
Impacts
What was accomplished under these goals?
Impact statement: Low moisture food safety is a growing concern with recent cases of foodborne illness outbreaks and recalls of spices, nuts, chocolate, and other food ingredients. These outbreaks and associated food recalls pose huge economic burden on food industries. During the second year of the project, Dr. Subbiah's team evaluated the efficacy of ClO2 gas against Salmonella in commercial samples of chia seeds and walnuts. ClO2 was found to be fairly effective against Salmonella achieving a maximum of 3.5 log reduction in chia seeds and 2 log reduction in walnuts after exposure to ClO2 gas for 200- 300 min at a gas concentration of 10 mg/L and relative humidity of 80%-90%. Dr. Ponder's lab evaluated the effect of different media and supplements on the recovery of multiple strains of S. enterica and Enterococcus faecium NRRL B2354, from chlorine dioxide and hydrogen peroxide treated low moisture foods (LMF). It was found that non-selective media provided better recovery of bacteria from treated samples as compared to selective media. Furthermore, it is also imperative to study the quality of food post treatment during storage to ensure the applicability of the developed process/technology in commodity treatments. Therefore, Dr. Irmak developed protocols for the quality analysis of chlorine dioxide treated black peppercorns, cumin seeds, and dried basil leaves. The chlorine dioxide byproducts such as chlorate and chlorite contents in whole black peppercorn and cumin seeds were observed to be very low while dried basil leaves had considerable levels of byproducts which could be due to more retention of ClO2 gas by the leaves. The color of the treated samples were also determined and compared with untreated samples. To aid in the scale up of gaseous technologies, Dr. Takhar's lab worked on X-ray imaging of the food particles to understand the diffusion of different antimicrobial gases through them. MicroCT image of pepper was analyzed to determine the channels. The structure also showed several dead ends, which could cause stagnant flow thus reducing the efficacy of applied sanitizers. Objective-specific report: The overall goal will be achieved throughfour supporting objectivesand the associated tasks: Obj. 1a. Design and fabricate precise treatment systems. For hydrogen peroxide, the gas generator procured from Bioquell was used to control the gas concentration, temperature, air flow rate and exposure time precisely. Ozone gas generator and analyzer was successfully set up in the lab in collaboration with Ozone Solutions. Currently, treatment set up is being optimized to monitor and achieve stable ozone concentration in the chamber. Obj. 1b. Develop gaseous inactivation kinetic models. A five-serotype Salmonella cocktail was prepared from S. Agona 447,967, S. Montevideo 488,275, S. Mbandaka 698,538, S. Tennessee K4643, and S. Reading Moff 180,418 and used to inoculate chia seeds and walnuts. Bacterial inactivation on chia seeds was evaluated at three different gas concentrations (5, 7.5 and 10 mg/L), three RH levels (60, 70, and 80%), and five gas exposure times (1 - 5 h) at room temperature (25 ?C). Results indicated that D-value of chia seeds decreased with increasing gas concentration and RH. Maximum of 3.7 log reduction was achieved at a gas concentration of 10 mg/L and 80% RH with 300 min of exposure time. To improve the ClO2 efficacy, mild heating of samples was carried out at 40°C and 60°C following treatment to ClO2. It was found that mild heating at 60°C for 2 hours following ClO2 treatment further reduced Salmonella by 1 log. In addition, storage of treated samples for 5 days further reduced the Salmonella by 0.8 log. In case of walnuts, ClO2 treatment at gas concentration of 15 mg/L and 90 % RH exposed for 150 minutes achieved 1-2 log reduction of Salmonella while no significant log reduction was achieved by mild heating after the ClO2 treatment. Hydrogen peroxide treatment at gassing injection rate of 4 g/min for 55 min followed by dwell (no injection) for 15 min set at maximum temperature of 35°C achieved 2.6 log reduction of Salmonella on dried basil leaves. Storage time significantly affected the Salmonella inactivation in both the products. Storage for 48 h after the treatment further reduced the Salmonella by 0.5 and 2 log in black peppercorn and dried basil leaves, respectively. In case of chia seeds and walnuts, hydrogen peroxide treatment could only reduce Salmonella by less than one log and hence, was not effective in microbial inactivation. Obj. 2a. Develop recovery media and methodology. The effect of different recovery media and supplements on the recovery of multiple strains of S. enterica and E. faecium, from chlorine dioxide or hydrogen peroxide treated black peppercorns, dried basil leaves, and chia seeds was evaluated. On average, recovery of S. enterica was 3.43 log and 4.77 log CFU/g from ClO2 and H2O2 treated LMFs, respectively on the selective media Xylose Lysine Deoxycholate agar, while the average recovery on non-selective media was 4.50 log CFU/g and 5.74 log CFU/g from ClO2 and H2O2 treated LMFs, respectively. The use of non-selective media was correlated with increased recovery compared to selective media. In further studies, addition of sodium pyruvate, ferrous sulfate, or 3'3'-thiodiproionate supplements to MTSAYE did not show increased recovery compared to MTSAYE (P>0.05). On each treatment and LMF combination tested, there was no significant difference between the log reduction of S. enterica and E. faecium NRRL B2354, indicating its suitability as a surrogate under the test conditions. Obj. 2b. EvaluateEnterococcus faecium as a surrogate. In case of chlorine dioxide treatment of chia seeds, E. faecium was shown to have higher reduction compared to Salmonella at few treatment conditions. However, the microbial reduction was higher for Salmonella than E. faecium at all treatment conditions that achieved more than 3-log reduction of Salmonella. Therefore, when E. faecium had at least 3 log reduction, Salmonella had higher than 3-log reduction indicating that E. faecium can be used as a suitable surrogate for Salmonella for conducting the process validation of ClO2 gas treatment. However, for vaporized hydrogen peroxide treatment of dried basil leaves, E. faecium was less resistant (4.4 log reduction) than Salmonella (2.6 log reduction) at the best treatment conditions rendering it unsuitable for in-plant validation. Obj. 3. Develop and validate a multiscale modeling framework. MicroCT image of pepper was analyzed to determine the channels. Channels were observed to form 6% of total volume. Tortuosity of the channels was determined to be 5.93. A value greater than 1 implies that the channel paths are significantly wavy. The structure also shows several dead ends, which could cause stagnant flow thus reducing the efficacy of applied sanitizers. Obj. 4. Evaluate food quality attributes. Quality analysis of chlorine dioxide treated black peppercorns, cumin seeds, and dried basil leaves were completed. The chlorate and chlorite contents of whole black peppercorn and cumin seeds were observed to be very low. The source of important portion of chloride ions in these samples could be steam-sterilization process applied prior to chlorine dioxide treatment. However, dried basil leaves had considerable amounts of chlorate, chloride, and chlorite ions that indicate these ions are most probably due to breakdown of chlorine dioxide. Another important point observed is dried basil leaves retain chlorine dioxide more than black peppercorns and cumin seeds, therefore, its breakdown products were found to be higher.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Nurul Ahmad, Ian M. Hildebrandt, Shannon R. Pickens, Sabrina Vasquez, Yuqiao Jin, Shuxiang Liu, Lindsay A. Halik, Hsieh-Chin Tsai, Soo Kiat Lau, Roshan C. D'Souza, Sanjay Kumar, Jeyamkondan Subbiah, Harshavardhan Thippareddi, Mei-Jun Zhu, Juming Tang, Nathan M. Anderson, Elizabeth M. Grasso-Kelley, Elliot T. Ryser, Bradley Marks. 2022. Interlaboratory Evaluation of Enterococcus faecium NRRL B-2354 as a Salmonella Surrogate for Validating Thermal Treatment of Multiple Low-Moisture Foods. J Food Prot. doi: https://doi.org/10.4315/JFP-22-054
- Type:
Journal Articles
Status:
Submitted
Year Published:
2022
Citation:
Jose O. Garcia, Surabhi Wason, Jeyamkondan Subbiah, Joseph Eifert, Laura K. Strawn, and Monica A. Ponder. The effect of different media on the recovery of Salmonella enterica and Enterococcus faecium NRRL B 2354 from whole black peppercorns, basil leaves, and chia seeds treated with antimicrobial gasses. Submitted to Frontiers in Food Microbiology.
- Type:
Journal Articles
Status:
Submitted
Year Published:
2022
Citation:
Xinyao Wei, Tushar Verma, Sibel Irmak, Jeyamkondan Subbiah. Evaluation of the microbial reduction during the storage of black peppercorns, cumin seeds, and dried basil leaves post gaseous chlorine dioxide treatment. Submitted to Food Control.
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2022
Citation:
Summers, Edel, "Inactivation of Salmonella in Black Peppercorn by Fluidization with Hydrogen Peroxide Vapor" (2022). Biological Systems Engineering M.S. Theses, University of Nebraska-Lincoln.
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2022
Citation:
Jose O. Garcia. Evaluating Methods of Improving Recovery of Sub-lethally Injured Salmonella in Low Moisture Foods Treated with Antimicrobial Gas. Masters of Science in Food Science. Virginia Tech, May 4, 2022.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Wason, S. and Subbiah J. (2022). Improvement of gaseous chlorine dioxide inactivation of Salmonella spp. in chia seeds assisted by mild heating and its effect during ambient storage. International Association for Food Protection Annual Meeting, Pittsburg.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Wason, S. and Subbiah J. (2022). Inactivation of Salmonella enterica and Enterococcus faecium NRRL B-2354 in chia seeds by gaseous chlorine dioxide. Institute of Food Technologists Annual Meeting, Chicago.
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Verma, T., X Wei, BD Chaves, T Howell Jr, J Subbiah. 2022. Antimicrobial efficacy of gaseous chlorine dioxide for inactivation of Salmonella and Enterococcus faecium NRRL B-2354 on dried basil leaves. LWT, 153: 112488.
|
Progress 07/01/20 to 06/30/21
Outputs
Target Audience:During this period, we interacted with manufacturers of ozone and hydrogen peroxide systems, a large spice company, and the California Walnut Board. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? One graduate student gained hands-on experience in the interdisciplinary fields of food engineering, microbiology, and chemistry. The collaboration with food industries through this project enabled the student to develop soft skills and build network with industry personnel. Three master's students were trained on microbiological techniques including operation of biosafety cabinet, plating and enumeration techniques. One master student was provided training on the operation of gaseous system and handling of treated samples. Two undergraduate students were trained on the microbiological techniques including the preparation of media, diluents and operation of biosafety cabinet. One graduate student was trained on the basics of different recovery media and their formulations to evaluate the best media and diluent for the study. The project provided preliminary training to one graduate student on microCT imaging, sample handling, data collection and image analysis. How have the results been disseminated to communities of interest?We have published several journal articles and conference presentations to disseminate the results. What do you plan to do during the next reporting period to accomplish the goals? The microbial inactivation data for chlorine dioxide treatment in chia seeds is currently in progress and is anticipated to be completed by next year. Walnut samples were procured from the walnut board of California and the optimization of inoculation protocols for the same will be initiated this year. The preliminary experiments with vaporized hydrogen peroxide treatment of dried basil leaves and black peppercorns are being carried out and we anticipate that the data collection will be completed by next reporting period. For the ozone system, a controller for precise and stable management of process parameters such as gas concentration, relative humidity and temperature will be built and evaluated for its microbial inactivation efficacy. Preliminary experiments with ozone gas inactivation of Salmonella will be conducted in black peppercorns and dried basil leaves thereafter. Currently the formulation of the recovery media is being evaluated and different combinations of antioxidants (3'3'- thiodipropionate or sodium pyruvate) or neutralizing agents (ferric sulfate) are being tested. We anticipate that the media formulation for improved recovery of Salmonella relative to selective media will be determined for ClO2 samples in 2021. Preliminary experiments have also begun with H2O2 and we anticipate additional testing in 2022. Pore size distribution, pore connectivity, and tortuosity will be determined from x-ray images. The porous structure will be utilized to model gas flow to identify its distribution in the material.
Impacts
What was accomplished under these goals?
The safety of low moisture foods (LMF) is a growing concern across US owing to repeated foodborne illness outbreaks linked to LMF such as spices, nuts, spreads, and other food ingredients. These outbreaks and associated food recalls pose huge economic burden on food industries. A multidisciplinary team comprising of food engineers, microbiologists and chemist was formulated to design and develop a safe and effective microbial inactivation process for LMFs without compromising on food quality. Gas generators and treatment chamber (ClO2) with precise controls of gas concentration and relative humidity were procured from equipment manufacturers while treatment chamber specific for H2O2 was designed at Dr. Subbiah's lab. During the first year of the project, Dr. Subbiah's team evaluated the efficacy of ClO2 gas against Salmonella in commercial samples of black peppercorns, cumin seeds and dried basil leaves obtained from food companies. We observed more than 4-5 log reduction of Salmonella in black peppercorns and cumin seeds and dried basil leaves after exposure to ClO2 gas for 200- 300 min at gas concentration of 15 mg/L and relative humidity of 80%. Dr. Ponder's lab worked on analysis and optimizing enumeration protocols to achieve better recovery of bacteria from the treated samples. Furthermore, it is also imperative to study the quality of food produce post treatment to ensure the applicability of the developed process/technology in commodity treatments. Dr. Irmak's lab formulated the methodologies and analyzed the treated samples for ClO2 byproducts. Color of the treated samples was also determined and compared with untreated samples. To aid in the scale up of gaseous technologies, Dr. Takhar's lab is working on X-ray imaging of the food particles to understand the diffusion of different antimicrobial gases through them. Obj. 1. Perform head-to-head comparisons of the antimicrobial efficacy of chlorine dioxide (ClO2), hydrogen peroxide (H2O2), and ozone (O3) in products representative of LMF categories. Obj. 1a. Design and fabricate a treatment system with precise controls for process parameters such as gas concentration, relative humidity, temperature, and gas velocity. ClO2 gas generator (Model Minidox-M) was procured and a treatment chamber was custom designed in collaboration with ClorDiSys Solutions, Inc., Lebanon, NJ. For hydrogen peroxide, a gas generator was procured from Bioquell and was used to control the gas concentration, temperature, air flow rate and exposure time. In addition to a batch treatment chamber, an improved fluidized treatment chamber is currently being developed to fluidize the granular particles for better contact with the antimicrobial gas. Ozone gas generator and analyzer were successfully set up in the lab in collaboration with Ozone Solutions. Design and fabrication of a treatment chamber with precise control of process parameters are currently performed. Obj. 1b. Develop gaseous inactivation kinetic models forSalmonellaspp. in spices (black peppercorns), herbs (dried oregano leaves), nuts (walnut halves), and ingredients (chia seeds) as functions of gas type and process parameters. A five-serotype Salmonella cocktail was prepared from S. Agona 447,967, S. Montevideo 488,275, S. Mbandaka 698,538, S. Tennessee K4643, and S. Reading Moff 180,418 and used to inoculate black peppercorns, dried basil leaves or cumin seeds. Bacterial inactivation was evaluated at three different gas concentrations (5, 10, and 15 mg/L), three RH levels (60, 70, and 80%), and five gas exposure times (1 - 5 h) at room temperature (25 ?C). Treated sample (3 g) was serially diluted in neutralizing buffer and spread plated onto differential media. After incubation at 37 ?C for 24 ± 2 h, the D-value was calculated as the time taken for one log reduction of bacteria at a particular gas concentration. Results indicate that D-value of spices decreased with increasing gas concentration and RH. Greater than 5-log reduction was only achieved at a gas concentration of 15 mg/L and 80% RH with 300 min of exposure time. In case of dried basil leaves, D-value for Salmonella and E. faecium decreased from 68.5 to 46.5 min and 91.5 to 69.2 min, respectively, as the gas concentration increased from 5 to 15 mg/L at 70% relative humidity. Obj. 2: Investigate microbiological methods and an appropriate surrogate forSalmonellaspp. treated with GT treatments. Obj. 2a: Evaluate the suitability of different media formulations for recovery of Salmonella stresses by chlorine dioxide gas. Inoculated black pepper, dried basil leaves and chia seeds were treated with chlorine dioxide to achieve high lethality. The samples were sent to Virginia Tech where the recovery was compared using different formulations of media. Recovery was comparable if neutralizing buffer or if a sterile solution of 0.1% peptone was used as a diluent for the initial suspension of the products treated using chlorine dioxide. The use of the selective media XLD for recovery is associated with on average 1 log decrease in recovery of Salmonella from the ClO2 treated spices in comparison to a non-selective media containing tryptic soy agar, yeast extract and (mTSAYE). Obj. 2b: EvaluateEnterococcus faeciumNRRL B-2354 as aSalmonellaspp. surrogate for GT by comparing its inactivation kinetics. In black peppercorns and cumin seeds, population reduction was higher for Salmonella than E. faecium at all treatment conditions that achieved more than 4-log reduction of Salmonella. In case of dried basil leaves, E. faecium had higher D-values compared to Salmonella at all the conditions tested in this study. Therefore, E. faecium NRRL B-2354 was found to be a suitable surrogate for Salmonella and could be used for in-plant validation in the food industries. Obj. 3: Develop and validate a multiscale modeling framework for simulating the transport of gases in LMF under various process conditions to aid in industrial scale-up of GT technology. To identify the stagnant pores (with lower accessibility to diffusing gases), micro-Computed Tomography (microCT) experiments were conducted with three low moisture foods--chia seeds, peppercorn and basil leaves using Zeiss XMCT-400 scanner. The scan parameters were 40kV voltage, 200uA current with 901 total projections over 360-degree rotation. Single projection time for Chia seed and peppercorn was 5 s, and it was 3 s for basil leaves. The stack of images was collected at a voxel size of 4.5 micron for peppercorn and basil leaves, and 2.2 micron for chia seeds. Image rendering and contrast adjustment were performed using Avizo Fire (Thermal Fisher Scientific, Waltham, MA). Micro CT images showed that in chia seeds, porous channels are present under the seed coat and in the funicle. Major part of chia seed is composed of uniform porous structures formed from perisperm, endosperm and cotyledons. In basil leaves and peppercorn, porous channels of varying sizes are formed throughout the tissue. Obj. 4: Conduct chemical analyses for gaseous residues/byproducts and food quality attributes. An Ion Chromatography method (EPA Method 300) was used to analyze the inorganic byproducts of chlorine dioxide in treated samples that achieved >3 log reduction of Salmonella. At 80% relative humidity and 300 min exposure time, increasing the chlorine dioxide gas concentration from 5 to 15 mg/L the chlorate content increased from 0.31 to 0.63 mg/g in whole black peppercorn and 0.46 to 0.75 mg/g in cumin seeds. Even though the dried basil leaves were treated for a shorter time (125 to 200 min) at the same condition, the chlorate content (0.69 to 0.85 mg/g) was found to be greater than the other two spices.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Wason, S, Verma, T, Subbiah, J. Validation of process technologies for enhancing the safety of low-moisture foods: A review. Compr Rev Food Sci Food Saf, 2021; 1 43. https://doi.org/10.1111/1541-4337.12800
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Xinyao Wei, Tushar Verma, Mary-Grace C. Danao, Monica A. Ponder, Jeyamkondan Subbiah. Gaseous chlorine dioxide technology for improving microbial safety of spices, Innovative Food Science & Emerging Technologies,
Volume 73, 2021, 102783, https://doi.org/10.1016/j.ifset.2021.102783.
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Xinyao Wei, Sabrina Vasquez, Harshavardhan Thippareddi, Jeyamkondan Subbiah, Evaluation of Enterococcus faecium NRRL B-2354 as a surrogate for Salmonella in ground black pepper at different water activities,
International Journal of Food Microbiology, Volume 344, 2021, 109114, https://doi.org/10.1016/j.ijfoodmicro.2021.109114.
- Type:
Journal Articles
Status:
Accepted
Year Published:
2021
Citation:
Tushar Verma, Xinyao Wei, Byron D. Chaves, Terry Howell Jr., Jeyamkondan Subbiah. Antimicrobial efficacy of gaseous chlorine dioxide for inactivation of Salmonella and Enterococcus faecium NRRL B-2354 on dried basil leaves. LWT. Accepted.
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Xinyao Wei, Long Chen, Byron D. Chaves, Monica A. Ponder, Jeyamkondan Subbiah. Modeling the effect of temperature and relative humidity on the ethylene oxide fumigation of Salmonella and Enterococcus faecium in whole black peppercorn, LWT, Volume 140, 2021, 110742, https://doi.org/10.1016/j.lwt.2020.110742.
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Long Chen, Xinyao Wei, Byron D. Chaves, David Jones, Monica A. Ponder, Jeyamkondan Subbiah, Inactivation of Salmonella enterica and Enterococcus faecium NRRL B2354 on cumin seeds using gaseous ethylene oxide, Food Microbiology, Volume 94, 2021, 103656, https://doi.org/10.1016/j.fm.2020.103656.
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Soon Kiat Lau, Jeyamkondan Subbiah, HumidOSH: A self-contained environmental chamber with controls for relative humidity and fan speed, HardwareX, Volume 8, 2020, e00141, https://doi.org/10.1016/j.ohx.2020.e00141
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Wason, S. and J. Subbiah. 2021. Efficacy of gaseous chlorine dioxide on Salmonella enterica and Enterococcus faecium NRRL B-2354 in chia seeds (Salvia hispanica L.) . International Association for Food Protection Annual Meeting. July 18-21. Phoenix, Arizona.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Xinyao Wei, Sibel Irmak, Monica A. Ponder, Jennifer C. Acuff, Jeyamkondan Subbiah. Inactivation of Salmonella and Enterococcus faecium NRRL B-2354 in black peppercorn and cumin seeds using gaseous chlorine dioxide technology. International Association for Food Protection Annual Meeting. July 18-21. Phoenix, Arizona.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Xinyao Wei, Long Chen, Soon Kiat Lau, Sibel Irmak, Byron D. Chaves, Mary-Grace C. Danao, Jeyamkondan Subbiah. Inactivation of Salmonella and Enterococcus faecium NRRL B-2354 in black peppercorn and cumin seeds using gaseous chlorine dioxide technology. ASABE virtual meeting. July 12-16.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Wason, S. and J. Subbiah (2021). Modelling the thermal inactivation of Salmonella enterica in fine ground black pepper at different water activities . Institute of Food Technologists Annual Meeting (Virtual). July 19-23.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Tushar Verma, Monica A. Ponder, Jennifer Acuff, Sibel Irmak, Jeyamkondan Subbiah. Antimicrobial efficicay of gaseous chlorine dioxide technology for inactivation of Salmonella and E. faecium NRRL B-2354 on dried basil leaves, International Association for Food Protection Annual Meeting. July 18-21. Phoenix, Arizona.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Tushar Verma, Soon Kiat Lau, Terry Howell Jr., Jeyamkondan Subbiah. Thermal Inactivation Kinetics of Salmonella spp. and Enterococcus faecium NRRL B-2354 in Dried Basil Leaves. Institute of Food Technologists Annual Meeting (Virtual). July 19-23.
|
|