Progress 12/15/13 to 12/14/14
Outputs
Target Audience: - Academic scientists working in the area of food science -Industries looking to develop novel technologies to improve safety of fresh produce -Graduate and undergraduate students interested in food science related research Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? -A postdoc has been recently hired. How have the results been disseminated to communities of interest? -Research paper -Presentations in the upcoming conferences What do you plan to do during the next reporting period to accomplish the goals? -Develop more detailed understanding of oxidative species generated from photosensitiztaion of compounds -Evalaue the antimicrobial potential of UV-activated fructose -Explore new photosenitizers and evalaute their antmicrobial efficacy -Understand the impact of propsoed tehcnology on the quality offresh produce
Impacts
What was accomplished under these goals?
The overall goal of the proposed research is to investigate synergistic combination of novel, food-grade photosensitizers (fructose, gallic acid and others) and lightto improve the bacterial and viral inactivation rate in wash water and fresh produce.The underlying hypothesis of the proposed research is thatfood gradephotosensitizers dissolved in wash water will produce free radicals when exposedlight of various wavelengths. These free radicals will act synergistically with thelight (such as UV) to enhance microbial inactivation rate. This hypothesis is based on literature and our prior studies. UV processing is an attractive technology for bacterial and viral inactivation. However, its limited depth of penetration and non-homogeneous treatment due to rough and contoured shape of produce has impeded its use in produce industry. Conventional chlorine and hydrogen peroxide based sanitizers used for washing produce have significant limitations such as limited microbial inactivation and ineffectiveness in destroying internalized bacteria and viruses. The proposed approach addresses these limitations. Impact:Our results show thatfructose is capable of producing reactive oxidative species upon exposure to UV light. Research is underway to evaluate its effect on microbial inactivation. Several other safe, food grade compounds that can be sensitized by UV-visible light to inactivate bacteria and viruses are also being investigated and the results so far are promising with as much as 99.99% reduction in bacteria and viruses in model systems.Specific progress is discussed below: 1.Investigate free radicals generation from novel photosensitizers (fructose and gallic acid) upon exposure to UV light in aqueous solutions and a model 3-dimensional solid system We observed that fructose was able to generate reactive oxygen species including free radicalsupon exposure to UV light in a model system. This work was recently published in a scientific journal. Further research is underway to characterize the nature of these reactive oxygen species. So far, we have found that singlet oxygen and hydrogen peroxide were produced upon exposure of fructose to UV light. This is a promising result, as both these species are known to inactivate microorganisms. Preliminary experiments in a 3-dimensional system show that the reactive oxidative species were able to penetrate in a 3 dimensional matrix for up to 500 micrometer depth. These results are also promising as they indicate that the proposed approach may be able to inactivate microorganisms not only present on the surface of fresh produce but also localized inside the fresh produce. 2. Evaluate efficacy of simultaneous action of photosensitizers and UV exposure on bacterial and viral inactivation in aqueous medium and fresh produce (surface and internalized) In addition to fructose and gallic acid, we are currently evaluating zinc oxide, rose bengal and titanium dioxide as potential photosensitizers for inactivation of bacteria and viruses. Results in model systems show that both zinc oxide and rose bengal were able to inactivate at least 99.99% of bacteria and virusesupon activationUV-visiblelightin the presence of organic content.We observed that the rate of inactivation is affected by presence of organic matter and the physiologicalstate of bacteria. Despite the presence of high organic content, the food grade photosensitizers are able to inactivatemore than 3-4 log reduction in microbial content in less than 1 hour of light exposure. We expect to publish these results in coming months. In addition tolight basedsensitizationof food grade photosensitizers, we are also evaluating the role of ultrasound based photo activation approaches. These approaches are in the preliminary stages. We are alsoin conversation with an investment company to perform "technology capability" experiments for sanitization ofawhole chicken. 3. Measure the impact of proposed approach on quality of fresh produce We expecttoperform experiments related to this objective during the third year of the project.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Elsinghorst, A.; Tikekar R. 2014. Generation of oxidative species from ultraviolet light induced photolysis of fructose. Food Chemistry, 154, 276-281.
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