Performing Department
(N/A)
Non Technical Summary
Effective post-harvest food cleaning and sanitation are critical to preserve food quality, reduce health risks, and prolong the food shelf life to reduce waste. Currently, low-temperature plasma (LTP) is an emerging technology in both pre-and post-harvest food treatment for its low environmental impact, high efficacy, and decentralized operation. However, current LTP technologies for water treatment, although being extensively studied on their sanitation performance, are typically not specifically designed for industrial applications where high-throughput continuous treatment and high energy efficiency are desired.This project aims to develop a new high-throughput LTP system to generate plasma-activated water (PAW) to address food safety inindustrial food processing facilities. Compared with current mainstream LTP technologies that adopt batch treatment with limited throughput, the proposed system features innovative Stack Wire Dielectric Barrier Discharge (SWDBD) reactor that can perform continuous water flow treatment. In addition, an energy-efficient high-frequency power supply with an energy harvest unit will be utilized to improve energy efficiency. Further, the proposed system can be easily scaled-up and deployed as an add-on system to the current water pipe to treat various food products.
Animal Health Component
0%
Research Effort Categories
Basic
40%
Applied
40%
Developmental
20%
Goals / Objectives
We aim to develop a novel low-temperature plasma system to generate Plasma Activated Water (PAW) for improved post-harvest produce sanitation to reduce food spoilage.Compared with current mainstream Chlorine-based treatment, the proposed system provides comparable or superior sanitation efficacy without hazardous chemical storage and with reduced environmental impact.
Project Methods
Task 1. Define RequirementsACT and NCSU will hold a kickoff meeting with USDA to review the project scope and establish the general guidelines for the program. A set of technical specifications for the bench-scale PAW generation system to be developed in the PI will be reviewed.Task 2. SWDBD Reactor and Gas Distribution System Optimization In this Task, we propose to conduct a parametric study to optimize the SWDBD reactor, specifically in 1) reactor design and geometry, 2) plasma power source and control 3) gas distribution system. For reactor design, the effect of ceramic coat thickness, ceramic material, and wire spacing on ozone generation and reactor temperature will be characterized. For power sources, a nanosecond pulse power source with duty cycle control will be tested for a suitable RONS production rate. The main hardware developed by ACT will be the plasma reactor. Other components (venturi injector, ozone destructor, etc.) are all commercially available.Task 3. Evaluating the Efficacy of PAW on Selected ProduceThe goal of this Task is to demonstrate the sanitation efficacy and reduction in losses in quality attributes (color and texture) using a PAW sanitation system and compared to a conventional chlorine-based sanitation system. The sanitation efficacy of PAW will be demonstrated on different classes of food produce, including food with smooth surfaces such as cherry tomatoes, and items with traditionally hard-to-sanitize surfaces, such as lettuce and kale. The microbial inactivation efficacy of PAW against representative gram-positive and gram-negative bacteria, including the common contaminants E. coli and L. innocua, will be demonstrated and compared to the conventional chlorine-based system. The changes in color and texture will monitored on the food surface post-treatment. The color characteristics of washed produce (L1*, a1*, and b1* ) will be compared to unwashed produce (L2*, a2*, and b2*) by calculating the total color difference (ΔE).The texture will analyzed using a texture analyzer (Stable Micro Systems, UK) by the maximum force required to fracture the produce sample. Details of the above tests can be found elsewhere.39Task 4. Bench-Scale System Integration and CharacterizationThe goal of this Task is to validate the proposed system design, including the controllable ozone/RONS generation with the SWDBD reactor. After the validation using the lab-scale system, a bench-scale (1 gallon/min) system will be built. The PAW property control, material compatibility, safety requirements, and overall system integration will be analyzed.Specifically, the effect of the gas flow rate, gas composition, feedwater quality, plasma power, and pulse frequency on the composition of the gaseous RONS and the properties of the generated PAW will be characterized. Optical emission spectroscopy measurements will be used for gas phase plasma characterization. The PAW samples will be analyzed by measuring the concentration of O3, H2O2, and nitrogen species (NO3-, NO2-) using ozone meter, colorimetric assays with UV-visible spectrophotometer,40 colorimetric assays based on modified Griess' reactions.41,42 The electrical conductivity and pH will also be measured. To evaluate the transient changes in PAW characteristics, the generated PAW samples will be stored in a controlled environment for 5-15 days and sampled intermittently. The results from this task will be used to explore the controllability and the uses of PAW with different properties.Task 5. Performance and Cost AnalysisThe performance and cost-effectiveness of the system will be analyzed considering the scalability of the system, integration with existing infrastructure, feasibility in replacement of current sanitation systems, material compatibility, and worker safety. The anticipated operational and capital costs, savings from both primary uses (post-harvest treatment of food) and secondary uses (surface sanitation around the facility) will be analyzed with regard to the anticipated sanitation efficacy, energy efficiency, and reduced water usage.Task 6. ReportingACT and NCSU will fulfill all required reporting requirements and accommodate any additional requirements preferred by the USDA NIFA Program Manager.