1a. Objectives (from AD-416):
1) Investigate the mechanism of bacterial attachment and persistence on fresh produce; 2) Investigate the dynamic effect of organic loads on sanitizer concentration and efficacy to inactivate pathogens; 3) Improve food quality and safety via novel technologies including active and intelligent packaging, surfactant applications, and antimicrobial gas treatments.
1b. Approach (from AD-416):
Design and fabricate a bioimaging system coupled with a PDMS-glass micro fluidic device to investigate the mechanism of bacterial attachment, persistence, and internalization. The PDMS-glass micro fluidic device will be specifically designed and engineered to biomimic the surface of fresh produce both topographically and biochemically. State-of-the-art bio-imaging and sensing instruments (e.g. Confocal, SEM, TEM, MRI, QCM-D, etc.) will be used in mechanism study. Attachment and internalization of non-pathogenic E.coli O157:H7, Salmonella, and Listeria with GFP and antibiotic markers will be observed directly under the imaging system. The interactions among sanitizer, reducing compounds in organic load, and hydrophobic plant surface will be evaluated using combined charactization methods, including micro fluidic device, microscopy (e.g. Confocal, SEM, TEM), chromatography (e,g, HPLC, GC/MS), biosensing (e.g. QCM-D), and other analytical instruments (e.g. UV-Vis, FTIR, NMR). Lastly, the study will endeavor to find a solution to improve efficacy of sanitizers to inactivate bacterial cells lodged in the indentations in the surface of fresh and fresh-cut produce via surfactant, redox-cycle, and/or nanomaterials (e.g. ZnO, biopolymer). In addition, this study will closely monitor the factors that affect the changes in chlorine concentration during produce washing. The active ingredient of organic materials from various produce products that are responsible for the loss of sanitizer concentration will also be isolated and characterized. Food grade surfactants will be screened for their potential to improve sanitizer efficacy for pathogen inactivation without compromising produce quality. Functional biopolymers will also be incorporated into packaging films, or edible films/coatings for a controlled release. Laboratory testing will be augmented with pilot plant trials.
3. Progress Report:
The agreement was formalized by the recruitment of a visiting scientist to undertake the studies. Research studies are being conducted to develop an artificial surface that simulates the topography and physical-chemical characteristics of fresh produce.