Source: CORNELL UNIVERSITY submitted to
MICROFLUIDICS AND PHYSICS-BASED APPROACHES TO ELUCIDATE PHYSICAL MECHANISMS OF FRESH PRODUCE CONTAMINATION
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
AFRI COMPETITIVE GRANT
Reporting Frequency
Annual
Accession No.
1005449
Grant No.
2015-67017-23087
Project No.
NYC-123563
Proposal No.
2014-05773
Multistate No.
(N/A)
Program Code
A1331
Project Start Date
Feb 15, 2015
Project End Date
Feb 14, 2019
Grant Year
2015
Project Director
Datta, A.
Recipient Organization
CORNELL UNIVERSITY
(N/A)
ITHACA,NY 14853
Performing Department
Biological & Environmental Eng
Non Technical Summary
We will know how disease causing microorganisms attach, grow and internalize in fresh produce. Also, what factors (like water flow and its level contamination) affect the contamination processes? When we have comprehensive knowledge of how things happen and what factors are most important, it should be easier (more efficient)for us to come up with ways to prevent contamination.
Animal Health Component
0%
Research Effort Categories
Basic
100%
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
71250102020100%
Knowledge Area
712 - Protect Food from Contamination by Pathogenic Microorganisms, Parasites, and Naturally Occurring Toxins;

Subject Of Investigation
5010 - Food;

Field Of Science
2020 - Engineering;
Goals / Objectives
To understand bacterial attachment and internalization, we propose a three-pronged, interdisciplinary, mechanistic approach involving engineering modeling, microfluidics and microbiology validation to study active and passive attachment and internalization at produce surfaces during exposure to contaminated water during irrigation/washing as well as passive infiltration into produce from hydro- and vacuum cooling. Applications include leafy greens and whole fruit. Our experimental approach applies microfluidics to capture processes at the bacterial scale along with microbiological and physical experiments at the real produce scale. Computational simulations include complementary approaches at various scales--particle tracking in fluid flow, microbial ecology using individual-based diffusion-reaction models, and porous media transport models at the produce scale. Synergy arising between experimentation and modeling should yield unprecedented understanding of attachment and internalization.Our quantitative understanding based on first principles complements rather than replaces current biological and experimental understanding, clarifying what happens between exposure and contamination, thereby reducing experimentation, and improving predictability.ObjectivesWe plan to elucidate the physical mechanisms of attachment and internalization by iteratively developing synergy between: a) physics-based mathematical models, b) microbiological experiments in microfluidics, and c) microbiological experiments on real produce. We repeat these three approaches or parts of them in three general categories:1. Mechanisms of passive attachment or internalization at produce surface from contaminated wash water2. Mechanisms of active attachment and internalization at fresh produce3. Mechanisms of passive internalization in intact produce
Project Methods
We will reveal the mechanism of attachment and internalization of microorganisms into fresh produce using i) mathematical modeling to highlight significant parameters governing these phenomena, ii) experimental microfluidics to mimic plant tissues and verify the models under controlled conditions, and iii) microbiological analyses for validating the proposed mechanisms. Here is a summary of our approaches:Mechanisms of passive attachment or internalization at produce surface from contaminated wash water:Develop a fluid flow-based particle-tracking model with varying fluid velocities, pore size, bacterial size and surface charge. Develop a microfluidic device with varying fluid velocities and surface conditions to observe attachment as a function of flow velocities/bacterial and solution concentrations. Obtain experimental data on attachment of bacteria over actual produce (spinach leaves) and compare against microfluidic and model results.Mechanisms of active attachment and internalization at produce surface:Develop an individual-based model (IbM) to predict the behavior of attached bacteria related to growth and biofilm formation, death, and taxis to specific locations. Develop a microfluidic device to observe the effects of chemical gradients that drive chemotaxis, growth, and biofilm formation and how temperature affects them. Obtain experimental data on internalization of bacteria over actual produce (spinach leaves) and compare against microfluidic and model results.Mechanisms of passive internalization in intact produceDevelop a porous media-based model to predict water and bacterial infiltration from hydrocooling of tomatoes and vacuum cooling of spinach. Obtain experimental data on internalization of bacteria in produce (tomatoes in hydro- cooling and spinach in vacuum cooling) and compare against model predictions.

Progress 02/15/15 to 02/14/19

Outputs
Target Audience:Due to the highly multidisciplinary nature of this project, people with different backgrounds and interests, working in academic research, industry and government, have been among the target audience. We developed physics-based models of attachment and growth of human pathogenic bacteria to the surface of fresh produce (such as spinach leaves), and bacterial infiltration into the fresh produce (such as spinach leaves and tomato) from various pre- and post-harvest environmental and process conditions, such as changes in temperature, pressure, light exposure and evaporation of surface water.The work was at the cutting edge of engineering and science, making it attractive in various disciplines. We published the outcomes of this project in scientific journals in various disciplines that cover a wide number of audiences. These journals include the Journal of Food Engineering, Postharvest Biology and Technology, Chemical Engineering Science, Physics of Fluids (special issue in Foods and Fluids), and Journal of Colloid and Interface Science. In addition, we shared our outcome at several national and international conferences. By presenting at the annual meeting of the International Association of Food Protection (IAFP) 2018, we introduced our findings to food scientists and microbiologists working in food safety and protection. Every year, we attended the annual meeting of the Institute of Food Technologists (IFT) and presented the work to food technologists working in many industrial sectors and universities. At annual meetings of the American Society of Agricultural and Biological Engineers (ASABE), every year we presented the work to several agricultural engineers working in microbial safety of agricultural products. The work was also presented at the Conference of Food Engineers (CoFE), 2016 and 2018, and the International Union of Food Science and Technology (IUFoST) 2018. The novel modeling approach developed during this project was also presented to several students, studying in science and engineering, through several workshops and short courses held in the US, Italy, and India. Changes/Problems:No major changes. We added additional modes of contamination contributed by chemotaxis. What opportunities for training and professional development has the project provided?Two PhD students were trained on this project, making them experts on this highly multidisciplinary topic of mechanistic understanding of food safety at the interface of science and engineering. The students took courses in mechanical and chemical engineering as well as courses in food science and microbiology. The students attended various conferences (ASABE, IFT, IAFP, CoFE, COMSOL) to present the outcomes of this project where they communicated with scientists and technologists with very different preparations. Laboratory training included those at Cornell MRI facility on imaging and Cornell Nanoscale Fabrication center (CNF) on multiple steps of design, fabrication, and characterization of microfluidic devices (artificial plant leaves). Both students were also trained for conducting microbiological experiments to measure the amount of bacterial infiltration into plant leaves. They were also trained in the most powerful mathematical modeling tools and techniques. How have the results been disseminated to communities of interest?The results have been published in eight papers in scientific journals in a very wide range of disciplines to reach the national and international community. These journals include the Journal of Food Engineering, Postharvest Biology and Technology, Chemical Engineering Science, Physics of Fluids (special issue in Foods and Fluids), and Journal of Colloid and Interface Science. The students and the PI attended several conferences to transfer the knowledge, such as ASABE, IFT, IAFP, CoFE, and COMSOL. Also, the work was presented to large groups of students, studying in science and engineering, through several workshops and short courses held in the US, Italy, and India, and to food companies. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? We developed physics-based models for: 1) passive attachment at produce surface from the contaminated wash water. The model is a fluid flow-based particle-tracking model with varying fluid velocities, pore size, bacterial size, and surface charge. 2) active attachment and growth at produce surface. The model is an individual-based model (IbM) for predicting behavior of the attached bacteria related to their growth and biofilm formation, death, motility, and taxis toward nutrient gradients. 3) passive internalization in intact produce. These are two porous media-based models to predict water and bacterial infiltration from hydrocooling of tomatoes and vacuum cooling of spinach and lettuce leaves. 4) active internalization into leafy greens. This is a porous media-based model that predicts the amount of light-driven chemotactic infiltration of bacteria toward photosynthetic products inside spinach leaves.5) retention and infiltration of bacteria on a plant surface during sessile droplet evaporation. This is a fluid flow-based model that explains how evaporation-driven internal flow within a sessile droplet at the surface of plant leaves can transport bacteria close to the surface and promote their infiltration into the leaf tissue. To support our findings related to this model, we also fabricated artificial plant leaf surfaces with known surface chemistry and roughness. With both the modeling and microfluidics approaches, we revealed the effect of various primary and secondary factors on bacterial infiltration during the droplet evaporation process that can take place in various pre- and post-harvest processing occasions.

Publications

  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Datta, A. K. 2016. Toward computer-aided food engineering: Mechanistic frameworks for evolution of product, quality and safety during processing. Journal of Food Engineering 176: 9-27.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Warning, A., Bartz, J.A, and A. K. Datta. 2016. Mechanistic understanding of temperature driven water and bacterial infiltration during hydrocooling of fresh produce. Postharvest Biology & Technology. 118:159-174.
  • Type: Journal Articles Status: Submitted Year Published: 2019 Citation: Ranjbaran, M., M. Solhtalab, A. Datta and L. Aristilde. 2019. Mechanistic modeling of light-induced chemotactic infiltration of bacteria into leaf stomata. Submitted to Plant, Cell & Environment.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Ranjbaran, M. and A. K. Datta. 2018. Pressure-driven infiltration of water and bacteria into plant leaves during vacuum cooling: A mechanistic model. Journal of Food Engineering, 246:209-223.
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Warning, A. D. and A. K. Datta. 2017. Mechanistic understanding of non-spherical bacterial attachment and deposition on plant surface structures. Chemical Engineering Science, 160: 396-418.