Performing Department
(N/A)
Non Technical Summary
Sanitation within dry food processing settings to prevent environmental cross-contamination and ensure the food safety of low moisture foods(LMF) has been recognized as a challenge for more than a decade. Specifically, environmentalSalmonellaposes a nationally significant public health risk, causing industry recalls, economic burden, and consumer morbidity/mortality.Recent outbreaks of Salmonella associated with environmental cross-contamination highlight the importance of dry surface sanitization controls to eliminate persistent pathogens. Despite the existing thermal technologies, limited studies assess microbial lethality on food processing surfaces, nor identify a suitable surrogate and surface inoculation protocol for thermal surface sanitization studies. Similarly, "hard-to-clean" locations in food processing equipment, which may include close-fitting metal-to-metal parts (e.g., rivet, joints), wheel casters, or interlocking mesh in conveyor belts, may shelter pathogens and further inhibit the efficacy of sanitation approaches. Thus, hard-to-clean locations are a significant barrier for effective environmental sanitation regimens, confirming the need for methods to conduct effective thermal surface sanitization to inactivate pathogens within hard-to-clean locations.The goal of this project is to develop strategies to eliminate pathogens within hard-to-clean locations of food production equipment. This includes developing protocols for surface inoculation and thermal surface sanitization interventions (i.e., hot air, saturated steam, and superheated steam) forSalmonellaand suitable bacterial surrogates. Secondly, developing and validating a predictive model for thermal surface inactivation of Salmonelllafrom superheated steam within hard-to-clean locations of variable dimensionswithin food processing facilities. Lastly, steam "tenting" will be assessed as a thermal surface sanitization intervention to improve microbial lethality within these locations. These findings will optimize the thermal surface sanitization approaches for hard-to-clean locations in food processing equipment by providing the industry evidence-based guidelines and novel strategies for thermal inactivation of Salmonella within LMF settings.
Animal Health Component
0%
Research Effort Categories
Basic
30%
Applied
30%
Developmental
40%
Goals / Objectives
The goal of this project is to develop strategies to eliminate pathogens within hard-to-clean locations on the surface of food production equipment.Objective 1: Develop methods for surface inoculation and thermal surface sanitization research.Objective 2: Develop and validate a model for surface thermal inactivation to predict microbial lethality from superheated steam within "hard-to-clean" locations.Objective 3: Evaluate the efficacy of steam "tenting" for thermal surface sanitization within "hard-to-clean" locations.
Project Methods
Objective 1:Experiement 1.1: I will initially assess a suitable protocol for surface-inoculation and surrogate selection (Enterococcusfaecium NRRL B-2354, Escherichia coliATCC 25922,Pediococcus acidilacticiATCC 8042) for thermal surface inactivation studies withSalmonella entericaEnteritidis PT30 on stainless steel surfaces. Microbial survival and recovery will be quantified for different inoculation methods: (1) immersion, (2) spray, and (3) spot surface inoculation followed by air dry-down. For method (1), the surface will be submerged into gently agitated liquid inoculum. For method (2), liquid inoculum will be administered to the target surface via a spray bottle. For method (3), liquid inoculum will be surface spot in the geometric center of the coupon and dried for different time intervals. Inoculated surfaces will be hand massaged within a Whirl-Pak bag to recover microbial populations.Experiment 1.2:Next, I will characterize the come-up time and surface temperatures on stainless steel surfaces during isothermal interventions of (1) saturated steam, (2) superheated steam, and (3) hot air. Target surface temperatures will include 100, 125, 150, 175, and 200°C. For methods (1) and (2), I will use a superheated steam HGA-S-01 bench-scale sanitizing unit to treat surfaces in an enclosed, steam chamber. For method (3), I will leverage forced hot air within the same processing chamber at a constant flow rate. I will measure the surface temperatures at the geometric center and corners (both sides) and the ambient temperature over time.Experiment 1.3:Thermal destruction curves will be constructed from surviving microbial population data. After thermal treatment, surfaces will immediately be transferred to a Whirl-Pak, then submerged in an ice ethanol bath. Inactivation kinetics (i.e., decimal reduction value and temperature sensitivity) for surrogates andSalmonella will be estimated by fitting log-linear and Weibull models with the experimental results. Goodness of fit will be estimated through the coefficient of determination (R2) and root mean square error (RMSE). Selection criteria of the surrogate for thermal surface inactivation studies will be based on thermal resistance under standardized processing conditions, in which the survival rate of the surrogate will be comparable, yet more conservative (i.e., heat stable) thanSalmonella.Objective 2: Experiment 2.1:I will characterize the structural dimensions of hard-to-clean locations via depth and width. A custom frame will befabricated to simulate hard-to-clean locationsbypositioning 2 stainless steel surfaces in an acute angle, subsequently forming custom structures of various depths and widths. The width will beaugmented to calibratethe distance at the opening of the structures.Experiment 2.2:Next, I will characterize the surface temperature gradients within these variable structural dimensions by conducting experiments with a pilot-scale superheated steamunit. I will position the steam nozzle at the geometric centerline of the fixed surface and determine the come-up times to achieve steady-state surface temperatures. Flow rate will regulate surface temperature. I will measure temperature at the (i) nozzle outlet, as well as on the surface of the structure at the (ii) opening, (iii) half-way between the opening and terminus, (iv) terminus, and (v) perpendicular (1 and 2 cm) from steam centerline. Distance between the steam nozzle and structure opening will be augmented.Contour plots will be used to visualize surface temperature throughout the structures.Experiment 2.3:I will develop a cumulative lethality-time model to estimate microbial inactivation on the surface of the structures based on the recorded surface temperature. I will use the inactivation kinetic data from Obj. 1 to build the model, and estimate microbial death within the structures based on the surface temperature gradients recorded in Exp. 2.1. To validate this predictive model, I will compare the estimations to experimental microbial inactivation achieved by the pilot-scale superheated steamunit. Microbial challenge studies will be conducted with the structural dimensions that most limit the come-up time and surface temperatures in Exp. 2.2.Objective 3: Experiment 3.1:I will characterize the surface temperature gradients and come-up times within the structures fabricated in Experiment 2.2. I will enclose the structures with polysheet and secure it with zip ties as in industrial settings. The temperature within the steam tent will be recorded, as well as the surface temperatures at locations (ii) to (v) as described in Obj. 2. The steam nozzle will be aligned within the poly sheet at the geometric centerline of the structure. Quantitative and quantitative observations will determine if any moisture collects within the tent.Experiment 3.2:Next, I will assess the efficacy of microbial inactivation within the structures during steam tenting, as a function of time. I will utilize approaches described above to inoculate select locations on the structure and implement the protocol for steam tenting, temperature recording, and moisture quantification denoted in Exp. 3.1. A Response Surface Methodology model using central composite design will be fit for microbial reductions based on surface temperature, time, moisture introduction, depth, and distance on the surface from steam centerline. A final model will be fitted with the highest order terms, R2, and RMSE. Acontour plot willvisualize the findings.Experiment 3.3:Finally, I will assess the efficacy of microbial inactivation during steam tenting for at least two pilot-scale examples, including a conveyor roller and fastener (e.g., rivet). I will measure the structural dimensions of the examples and implement the protocols for a microbial challenge study as denoted in Exp. 3.1.Evaluation Plan: Research:I will disseminate my research results at least twice per year to my lab and the Cornell graduate community. I will annually present my findings at least once at conferences, including International Association of Food Protection. I will publish my findings after each objective as first author to peer-reviewed accredited journals (at least 3 publications) to disseminate research to the scientific community.ProfessionalDevelopment:I will annually attend at least 2workshops directed by Cornell's Statistical Consulting Unit, and Graduate Writing Service. I will complete at least 1workshop through Cornell GET SET program to develop strategies for inclusive teaching and active learning. I will communicate with at least three industry affiliates at conferences to assess practical relevance of these objectives. I will document my research progression on LinkedIn, OrcID, and Research Gate.Mentorship:I will coordinate weekly meetings with Dr. Snyder for research feedback and assess professional development during an annual progress review. I will communicate with my collaborating mentors several times per year. I will mentor three students and assess their growth through progress reports. I will communicate with industry personnel through IAFP, Cornell Agritech, and the Cornell Advisory Councils (Food Science and Architecture) for insight about steam tenting and thermal processing of "hard-to-clean" locations.