Progress 12/15/13 to 12/14/16
Outputs
Target Audience:
Nothing Reported
Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? CIRAD - Joint Research Unit for Agropolymer Research and Emerging Technologies (UMR IATE), Montpelier, France. University of Bologna (Italy) - This project provided support for the training of a visiting graduate student in food science from the University of Bologna. How have the results been disseminated to communities of interest?We have disseminated the results and major findings of our work through the peer review literature, as talks and posters in several interntional scientific meetings, and through short courses and public seminars. These are described in the previous section . What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
As we discussed in our previous interim progress reports, we were not able to complete the tasks associated with Objective 1 of the project. This objective focused on using electron paramagnetic resonance (EPR) spectroscopy to directly observe the partitioning behavior of an EPR-active (paramagnetic) spin probe in a model food oil-in-water (o/w) emulsion. Based on preliminary data from our lab and elsewhere, such an experiment seemed feasible, as partitioning kinetics could be calculated in micellar systems. Unfortunately, we quickly discovered that many aspects of the proposed experiment were confounded by the relatively complex system (o/w emulsion vs the more simple micelle system that was used in previous studies). Our project staff, in particular Dr. Erwann Durand (postdoc assigned to the project) spent at least 6 months during the first phase of the project in an attempt to modify the model system in order to make it amenable to our spin probe partitioning experiment with limited to no success. These modifications included the following: Removal of non-adsorbed, continuous phase surfactant in emulsions using ultra centrifugation and filtration to reduce/eliminate the confounding effects that these species have on spin probe partitioning between aqueous, lipid, and emulsion interfacial phases. Established a new collaboration with a Penn State chemistry faculty member with advanced EPR instrumentation with cryostat controlled cavities that allowed for low temperature experiments. Reformulation of our model emulsion systems Selected alternative spin probes other than 5-DSME, including both commercially available spin probes that could be argued were structurally analogous to tocopherol, as well as spin probes that we synthesized in-house by derivatizing the stable spin label (2,2,6,6-Tetramethylpiperidin-1-yl) oxyl (TEMPO) with various aliphatic chains. Once it became clear that the experiments supporting Objective 1 could not be completed within the project performance period, we decided to move on to Objective 2, which focused on understanding how emulsion design/parameters could influence antioxidant synergy. Specifically, this objective was designed to first test the hypothesis that lipid soluble antioxidants (e.g., tocopherol) could interact with - and potentially be regenerated by - aqueous phase constituents (e.g., ascorbic acid, phenolics). As hydrophobic antioxidants like tocopherol tend to partition deep within lipid droplet cores and are physically isolated from emulsion interfaces (which are known to be the sites of oxidation reactions), they are physically isolated from water soluble components (e.g., ascorbic acid) that could potentially regenerate them. Based on our preliminary data, and the results we obtained as part of Objective 2, we were able to determine that such interaction could be modulated in food emulsions by varying emulsion ingredients/preparation, but only to a limited degree and to an extent that was smaller than previously thought. We were also successful in developing a novel method for assessing these complex interactions in heterogeneous systems such as o/w emulsions. The bulk of this work was published (Durand, E., Zhao, Y., Coupland, J. N., & Elias, R. J. (2015). Assessing interactions between lipophilic and hydrophilic antioxidants in food emulsions.J. Agric. Food Chem. 63(49), 10655-61.DOI: 10.1021/acs.jafc.5b04152) and presented at a number of international meetings as both oral and poster presentations. We have submitted two other manuscripts based on this work to the peer review literature, both of which are currently under review.
Publications
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Progress 12/15/14 to 12/14/15
Outputs
Target Audience:
Nothing Reported
Changes/Problems:The only change we can report here is the additional experiment involving protein-stabilized emulsions (described in the final section of "Accomplishments"). What opportunities for training and professional development has the project provided? CIRAD - Joint Research Unit for Agropolymer Research and Emerging Technologies (UMR IATE), Montpelier, France. How have the results been disseminated to communities of interest?We have disseminated the results and major findings of our work through the peer review literature, as talks and posters in several interntional scientific meetings, and through short courses and public seminars. These are described in the previous section . What do you plan to do during the next reporting period to accomplish the goals?We aim to perform a follow-up study based on the work of MS student D'Amicis this spring and summer. This project will focus specifically on the effect that protein emulsifiers have on antioxidant interactions in oil-in-water emlusions. While this project is not explicitly described in the original proposal, it clearly relates to the overall theme of the project and, if successful, would yield interesting results in support of the project area.
Impacts
What was accomplished under these goals?
Our first major objective (i.e., monitoring TCP partitioning directlyusing electron paramagnetic resonance (EPR) spectroscopy) was not fully achieved. It quickly became clear that, due to the complex matrix involved and the relatively short half lives of the radical species in question, it would not be possible to probe our target system in the way described in our original proposal. Therefore, we decided to shift our focus and energies to objective #2, which we believed had a higher likelihood of success and, if completely successful, would serve to address objective #1. We were able to design a novel analytical method for assessing antioxidant interactions - specifically antioxidant regeneration mechanisms - between lipid phase solvated antioxidants (e.g., tocopherol) and aqueous phase antioxidants (e.g, ascorbic acid, catechin, epigallocatechin gallate). The method itself, along with the results of our interaction study that we had originally proposed in objective #2 of the proposal, was submitted to and accepted for publication by the Journal of Agricultural and Food Chemistry (an American Chemical Society publication) in 2015. In further support of objective #2 and, in part, objective #1, we completed a major study that investigated how emulsion composition and properties affect antioxidant interactions in that system. For this, we employed the novel analytical approach described above, as well asdirectly following tocopherol loss and lipid oxidation markers. This phase of the project was performed by a graduate student under the supervision of the project staff.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
Durand E., Zhao Y., Coupland J.N., Elias R.J. Assessing interactions between lipophilic and hydrophilic antioxidants in food emulsions. J. Agric. Food Chem., 2015, 63, 1065510661. DOI: 10.1021/acs.jafc.5b04152.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Elias R.J. Effect of lipophilization on the distribution and reactivity of emulsion ingredients. DOF 2015 - 6th International Symposium on Delivery of Functionality in Complex Food Systems, July 14-17, 2015. Paris, France.
- Type:
Other
Status:
Other
Year Published:
2015
Citation:
Elias R.J. Using EPR to understand oxidation reactions in multiphase systems. EPR in Food Science Shortcourse, ETH Zurich, February 1-6, 2015. Arona, Switzerland.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Durand E., Zhao Y., Coupland J.N., Elias R.J. Understanding the dynamic behavior of functional molecules: an electron paramagnetic resonance (EPR) spectroscopy approach. 13th Euro Fed Lipid Congress, September 27-30, 2015. Florence, Italy.
- Type:
Other
Status:
Published
Year Published:
2015
Citation:
Elias R.J. Solving problems in food chemistry using electron paramagnetic resonance spectroscopy. Department of Chemistry Seminar Series, Juniata College. April 14, 2015. Huntingdon, PA.
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Progress 12/15/13 to 12/14/14
Outputs
Target Audience:
Nothing Reported
Changes/Problems: As discussed in the previous section ("Accomplishments"), we did have to make some changes to our approach with respect to methodology; however, we do not consider these to be "major changes/problems", as we have been able to address some of our Year 1 aims using alternate protocols. What opportunities for training and professional development has the project provided? This project has created the opportunity for the training of two individuals: 1. Dr. Erwann Durand (Postdoctoral research associate) is the key staff member on this project. He is being fully supported by this grant. 2. Yu Zhao (PhD student) has assisted on key aspects of the projects. Dr. Durand has been an important mentor to him as a result of the project. How have the results been disseminated to communities of interest? Dr. Durand has presented some of the preliminary findings of the study at a postdoctoral research symposium (Penn State). As stated above, a manuscript will be submitted in the coming weeks. What do you plan to do during the next reporting period to accomplish the goals? As mentioned in the above section, we are exploring alternative methods (i.e., isotopic labeling of tocopherol) that will help us address our central hypotheses; this will be done in parallel to the approaches we outlined in our proposal. We will also begin our work towards subsequent aims (Year 2), specifically looking for tocopherol/reductant synergy in a more complex system (i.e., oil-in-water emulsion prepared with oxidative labile organic phase).
Impacts
What was accomplished under these goals?
We experienced some setbacks with our first objective, as direct observation of the tocopherol radical by electron paramagnetic resonance proved to be extremely difficult. We were able to observe this stable radical in a much simplified system; however, once we moved to a more relevant / generalizable system (i.e., a surfact-stabilized oil-in-water emulsion), the apparent half life of the tocopherol radical was greatly reduced. As a result of these technical challenges, we were forced to change tactics a bit and to attempt to address our key hypothesis (these are described below). 1. We designed experiments that could demonstrate (although not directly) tocopherol regeneration by aqueous phase reductants. Tocopherol concentrations were followed by normal phase HPLC. We are confident that we have demonstrated some degree of antioxidant synergy here, albeit indirectly. We have prepared a manuscript that describes these results, which will be submitted a peer-review journal in the coming weeks. 2. We are now exploring methodology that will allow us to follow tocopherol / reductant interactions directly using isotopically labelled (d2) tocopherol. The postdoc staffed on this project (Erwann Durand) has extensive experience in organic synthesis, and is currently conducting these experiments. 3. We have been in contact with Bruker BioSpin (EPR division) and will be traveling to their facilities in Billerica, MA in the coming months to re-attempt our direct tocopherol radical observation experiments using their equipment.
Publications
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