Progress 09/01/09 to 08/31/13
Outputs
Target Audience: The primary audience for our researech are food scientiests working in universities, the food industry, and government laboratories on understanding antioxidant efficiency and engineering antioxidants and food system to maximize the stabilization of food emulsions against peroxidationof polyunsaturated oils. Romsted teaches a graduate course in Supramolecules and Assembiles every other year in the Department of Chemistry and Chemical Biology. Two graduate students, a prior Post Doc and a Post Doctoral Fellow from Kashmir, India worked in Romsted's group on projects related to sntioxidant distributions in emulsions and to modeling chemical reactivity in mixed nonioinic/cationic micelles. Om Professor Qingrong Huang's group a post doctoral fellow and two graduate students worked on this project. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? In Romsted’s group, the two graduate students and two post doctoral fellows worked on this project last year and the current year, doing the major research work on this project. The graduate students, Xiang Gao and Qing Gu, give presentations from the current literature periodically throughout the year. They all have attended national meetings and presented posters and in some cases given a talk, including a Gordon Conference, an ACS Colloid and Surface Science meeting, and a Mid Atlantic ACS Meeting. All three have also been introduced to modern instrumentation, NMR, UV/VIS, electrochemistry, and, in particular, HPLC the mainstay of the group. I also teach a course call Supramolecules and Assemblies. In Professor Qingrong Huang’s group, a post doctoral fellow and two graduate students worked on this project during the final year of the project. How have the results been disseminated to communities of interest? The primary methods of dissemination have been by publication of papers in food and related journals and by attending meetings. Romsted’s Group Romsted’s students have also presented posters and in some cases given a talk at national meetings including Gordon Conferences, ACS Colloid and Surface Science meetings, and Mid Atlantic ACS Meetings. 1. “Harnessing Kinetics to Estimate Antioxidant Distributions in Emulsions Composed of Cationic and Anionic Surfactants and to Demonstrate a Surprisingly Modest Sensitivity of Observed Rate Constants on Emulsion Droplet Size from Micro to Nano,”Nineteenth Surfactants in Solution Symposium, University of Edmonton, Canada, June 24-29, 2012. 2. “Simultaneous Determination of Interfacial Molarities of Amide Bonds, Carboxylate Groups, and Water by Chemical Trapping in Micelles of Amphiphile Containing Peptide Bond Models,” Eminent Speaker, Workshop on Micelle Dynamics, Catalysis and Solublization, March 12, 2013, Dharmisinh Desai University, Nadiad, India. 3. “Determining Antioxidant Distributions between Oil, Water, and Interfacial Regions of Emulsions: Generalization of Pseudophase Kinetic Models,” Keynote Lecturer, International Conference on Emerging Trends in Chemical Sciences at Central University of Gujarat, Gandhinagar, India, on 14th-15th March, 2013. 4. “Applications of Pseudophase Kinetic Models to Surfactant Solutions: From Modeling Chemical Reactivity to Probing the Delicate Balance of Forces Governing Self-Assembly by Chemical Trapping,” Institute of Chemistry, University of Sao Paulo, Sao Paulo, Brazil, Friday, April 5, 2013. Part of a two-day program on Academic Opportunities at Rutgers and Ohio State. Professor Qingrong Huang’s group. (1) Zhao, Q.; Ho, C.-T.; and Huang, Q. R. (2013) Effect of ubiquinol-10 on citral stability and off-flavor formation in O/W nanoemulsions, Journal of Agricultural and Food Chemistry, 61, 7462-7469. (2) Liang, R.; Shoemaker, C.; Yang, X. Q.; Zhong, F.; and Huang, Q. R. (2013) Stability and bioaccessibility of beta-carotene in nanoemulsions stabilized with modified starches. Journal of Agricultural and Food Chemistry, 61, 1249-1257. (3) Yu, H. L.; and Huang, Q. R. (2013) Investigation of the cytotoxicity of food-grade nanoemulsions on Caco-2 cell monolayers and HepG2 cells. Food Chemistry, 141, 29-33. (4) Ting, Y. W.; Xia, Q. Y.; Li, S. M.; Ho. C. -T.; and Huang, Q. R. (2013) Development of high-loading and high-stability emulsions for polymethoxyflavones. Food Research International, 54, 633-640. (5) Karadag, A.; Yang, X. Q.; Ozcelik, B.; and Huang, Q. R. (2013) Optimization of conditions for the preparation of quercetin nanoemulsions using response surface methodology. Journal of Agricultural and Food Chemistry, 61, 2130-2139. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Significant progress was made in two major directions toward the goals of this project: (a) developing new strategies in encapsulating and stabilizing flavors in food emulsions; and (b) developing a powerful new method for determining antioxidant (AO) distributions in emulsions that works across a wide range of component types and concentrations. Professor Huang’s group completed a series of studies on the use of nanoemulsions and antioxidants to stabilize citral and other methods for stabilizing flavor components. For example, an optimal concentration of ubiquinol-10, which is also a functional ingredient to improve human health, in citral loaded oil/water nanoemulsions gave significant protection to citral, but higher or lower concentrations of ubiquinol-10 were less effective. Oil in water nanoemulsions prepared with modified starch emulsifiers were used to improve stability and bioaccessibility of ?-carotene. Modified starch with highly dispersed molecular density increased beta-carotene retention, but reduced bioacessibility in nanoemulsions. The results should aid in the creation of new protection and delivery systems for carotenoids. Similarly, results with quercetin loaded nanoemulsions showed that optimum formulations occurred with mixed tween/span emulsifiers at about 13%, with 17% limonene and at 70 MPa homogenization pressure. Particle size depended on the percentage of quercetin and that emulsion stability depended on the oil:emulsifier ratio. A careful investigation of the cytotoxicity of food-grade nanoemulsions showed that both nano- and micro-sized emulsions indicated no toxic effect on the small intestine. However, nanoemulsions affected cell viability and proliferation more than micron sized emulsions indicated the need for further in vivo study of possible hepatic toxicity of nanoemulsions. A new method for forming highly stable viscoelastic emulsions that encapsulate high loads of crystals of polymethoxyflavones (PMFs), which possess various biofunctionalities. The viscoelastic structures prevent sedimentation of the crystals and slow the dissolution of PMFs considerably. Together, this research suggests that nanemulsions may play an important role in stabilizing nutraceuticals. Romsted’s group developed a new chemical kinetic method, based the application of pseudophase models to emulsions, for using changes in the observed rate constant between a special hydrophobic arenediazonium ion probe and an AO, to estimate the AO’s distribution in three component emulsions, typically oil, emulsifier, and water. The data fitting provides estimates of AO distributions between the oil and interfacial and aqueous and interfacial regions of the emulsions over a range of oil to water ratios and stoichiometric emulsifier concentration. A review article was published in 2013 in Current Opinion in Colloid and Interface Science that described progress to date, including: (a) two methods for estimating the partition constants for substrates between the oil-interfacial, POI, and water-interfacial,PWI, regions of the emulsions; (b) methods for determining the rate constant in the interfacial region,kI; identifying the relative importance of various emulsion properties such as oil hydrophobicity, emulsifier structure and HLB. Representative results for antioxidants are included. Romsted and Faruk Nome were the section editors for this issue of COSIS. Romsted and coworkers published three papers on using the approach in new ways: (1) demonstrated specific anion effects on the reaction of the probe with t-butylhydroquinone (TBHQ) followed the Hofmiester series in zwitterionic emulsions; (2) that anionic and cationic surfactants had very different effects on the distribution of the AO and the pH at which the reaction could be monitored and that these effects fit the pH dependence of mechanism of the reaction of TBHQ with the probe; and (c) from changes in the measured rate constants as a function of temperature obtained the first estimates of the free energy, enthalpy, and entropy of AO distributions. The two most important papers demonstrate that the fraction of gallic acid and its esters with variable ester chain lengths (published) and caffeic acid and its esters (submitted) go through maxima with increasing ester chain length in emulsions. Hydrophilic AOs are mostly in the water, AOs of intermediate hydrophobicity are in the interfacial region and very hydrophobic AOs are primarily in the oil region. We found similar maxima at the same chain lengths in measurements of bulk antioxidant efficiency. This is a powerful support for the idea AOs are primarily active in the interfacial region and that the marked decrease in AO efficiency for hydrophobic AOs, the “cut-off” effect that has been reported multiple times, is attributable to the higher solubility of hydrophobic AOs in the oil region and reduced solubility in the interfacial region. Finally, Romsted’s edited book, “Surfactant Science and Technology: Retrospects and Prospects” appeared in May, 2014.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Modeling Chemical Reactivity in Emulsions, Laurence S. Romsted and Carlos Bravo-D�az, Current Opinion in Colloid and Interface Science, 2013, 18, 3-14.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Reactivity in Colloidal Systems and at Interfaces, Faruk Nome and Laurence S. Romsted Current Opinion in Colloid and Interface Science, 2013, 18, 1-2.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Using the pseudophase kinetic model to interpret chemical reactivity in ionic emulsions: determining antioxidant partition constants and interfacial rate constants, Qing Gu, Carlos Bravo-D�az, Laurence S. Romsted, Journal of Colloid and Interface Science, 2013, 400, 4148.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Interpreting Ion-Specific Effects on the Reduction of an Arenediazonium Ion by t?Butylhydroquinone (TBHQ) Using the Pseudophase Kinetic Model in Emulsions Prepared with a Zwitterionic Sulfobetaine Surfactant Xiang Gao, Carlos Bravo-D�az, and Laurence Stuart Romsted, Langmuir 2013, 29, 4928?4933.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Maxima in Antioxidant Distributions and Efficiencies with Increasing Hydrophobicity of Gallic Acid and its Alkyl Esters. The Pseudophase Model Interpretation of the Cut-off Effect. Sonia Losada Barreiro, Carlos Bravo-D�az, F�tima Paiva Martins, Laurence S. Romsted, Journal of Agricultural and Food Chemistry, 2013, 61, 6533-6543.
- Type:
Books
Status:
Published
Year Published:
2014
Citation:
Surfactant Science and Technology: Retrospects and Prospects, Laurence S. Romsted, editor, CRC Press, Taylor & Francis group, Boca Raton, 2014, in press. 20 chapters, by research groups from around the globe, ca. 600 pages. Publication May 8, 2014.
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Influence of Temperature on the Distribution of Catechin in Corn Oil-in-Water Emulsions and Some Relevant Thermodynamic Parameters. Nuria Mart�nez-Aranda, Sonia Losada-Barreiro, Carlos Bravo-D�az and Laurence S. Romsted Food Biophysics, 2014, DOI 10.1007/s11483-014-9332-9.
- Type:
Journal Articles
Status:
Under Review
Year Published:
2014
Citation:
A direct correlation between the efficiencies of caffeic acid alkyl esters and their mole fractions in the interfacial region of olive oil emulsions. The pseudophase model interpretation of the cut-off effect. Marlene Costa, Sonia Losada-Barreiro, F�tima Paiva-Martins, Carlos Bravo-D�az, Laurence S. Romsted, Food Chemistry,
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Zhao, Q.; Ho, C.-T.; and Huang, Q. R. (2013) Effect of ubiquinol-10 on citral stability and off-flavor formation in O/W nanoemulsions, Journal of Agricultural and Food Chemistry, 61, 7462-7469.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Liang, R.; Shoemaker, C.; Yang, X. Q.; Zhong, F.; and Huang, Q. R. (2013) Stability and bioaccessibility of beta-carotene in nanoemulsions stabilized with modified starches. Journal of Agricultural and Food Chemistry, 61, 1249-1257.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Yu, H. L.; and Huang, Q. R. (2013) Investigation of the cytotoxicity of food-grade nanoemulsions on Caco-2 cell monolayers and HepG2 cells. Food Chemistry, 141, 29-33.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Ting, Y. W.; Xia, Q. Y.; Li, S. M.; Ho. C. -T.; and Huang, Q. R. (2013) Development of high-loading and high-stability emulsions for polymethoxyflavones. Food Research International, 54, 633-640.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Karadag, A.; Yang, X. Q.; Ozcelik, B.; and Huang, Q. R. (2013) Optimization of conditions for the preparation of quercetin nanoemulsions using response surface methodology. Journal of Agricultural and Food Chemistry, 61, 2130-2139.
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Progress 09/01/10 to 08/31/11
Outputs
OUTPUTS: Key results to date: Hydrophobically modified polylysine graft copolymers were synthesized by reacting EPL with octenyl succinic anhydride (OSA). The success of the synthesis was confirmed by 1H NMR and FT-IR spectroscopy. OSA-g-EPL(s) had glass transition temperatures lower than EPL. They polymer micelles in water and lower the surface tension of water, confirming their amphiphilic properties. The antimicrobial activities of OSA-g-EPL(s) were examined and the minimum inhibitory concentrations of OSA-g-EPL(s) against Escherichia coli (E.coli) O157:H7 are the same as EPL. Therefore, OSA-g-EPL(s) are potentially bi-functional molecules for the encapsulation of nutraceuticals/drugs or as antimicrobial agents. The effects of oil-in-water (O/W) nanoemulsions, containing six different natural antioxidants, on the stability of citral were investigated. Acidic emulsions (lecithin stabilized palm kernel lipid in pH 3 buffer) containing 1000 ppm citral and 1000 ppm antioxidants (black tea extract, ascorbic acid, naringenin, tangeretin, beta-carotene and tanshinone) were stored at 25 oC and 50 oC, respectively. The emulsions, with and without antioxidants, were analyzed by solid phase microextraction gas chromatography (SPME-GC) to monitor the degradation process of citral and the formation of different off-flavor compounds, such as alpha,p-dimethylstyrene and p-methylacetophenone. The results suggested that encapsulation of citral in emulsions and the addition of the appropriate antioxidants (beta-carotene, tanshinone and black tea extract) could greatly enhance citral's chemical stability during storage. The pseudophase kinetic model was used to obtain new insight into the effect of antioxidant, oil, and emulsifier type on the distributions of antioxidants in emulsions. Correct characterization of antioxidant distributions in emulsions will aid in stabilizing citral in nano and larger emulsions. The summary below is organized by the papers listed in outcomes/impact or in press/published. (a) The method was used to determine the distributions of gallic acid, in a Tween 20/corn oil/acidic water emulsion with values for water to interfacial partition constant, the interfacial second-order rate constant and the enthalpy, entropy and free energy of transfer for gallic acid (ref 4, in press). (b) Determined partition constants between the aqueous and interfacial and oil and interfacial regions of an emulsion, gallic acid and some of its esters in the decreasing order: propyl gallate, gallic acid, octyl gallate, lauryl gallate. Measurements of oil oxidation inhibition in these emulsions showed that efficiencies correlate directly decreasing partition constants (ref a, in preparation). (c) Changes in kobs with increasing surfactant volume fraction and the effect of added salt on kobs are correctly described by the pseudphase model (ref b, in preparation). (d) Values of kobs for the reaction of the arenediazonium probe with TBHQ in MCT/aqueous acid/C12E6 emulsions at constant concentrations are independent of droplet sizes above 300 nm, but 2-3 fold larger for droplets between 100-300 nm (ref. c, in preparation). PARTICIPANTS: Qingrong Huang's Group and Chi-Tang Ho's groups: Drs. Xiaoqing Yang, Yuwen Wang, Huaixiang Tian, and Hailong Yu Laurence Romsted's Group: Dr. Tarek Awad and graduate students: Qing Gu and Xiang Gao. Unfunded collaboration with Carlos Bravo-Diaz at the University of Vigo, Spain. TARGET AUDIENCES: Researchers in universities, food industry, and government laboratories. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Losada-Barreiro, S.; Bravo-Diaz, C.; Romsted, L. S. Correlations between the efficiencies and distributions of gallic acid and gallic acid esters in olive and corn oil emulsions." Manuscript in final stages for Langmuir. Qing, G.; Bravo-Diaz, C; Romsted, L. S. "Effect of Emulsifier Charge and Acidity on the Distributions and Reactivities of the antioxidant of t-Butyl-hydroquinone in MCT,H2O,CTAB and MCT,H2O,SDS emulsions, Manuscript in final stages for Langmuir. Qing, G.; Bravo-Diaz, C; Romsted, L. S., "Dependence of Chemical Reactivity on Emulsion Droplet Size; from Nano to Micro Emulsions." In preparation for J. Agricultural and Food Chemistry. Romsted wrote a chapter for a new Encyclopedia of Supramolecular Chemistry on surfactant self-assembly, i.e., the spontaneous formation of micelles, microemulsions and vesicles. The common properties of surfactant aggregates were introduced, cmc, aggregation number, dynamic equilibrium, packing parameter, etc., and also a section on modeling chemical reactivity in association colloids. Volume 1 appeared in March, 2012.
Publications
- Yang, X. Q.; Tian, H. X.; Ho, C. T.; and Huang, Q. R. "Inhibition of Citral Degradation by Oil-in-Water. 2. Nanoemulsions Combined with Antioxidants." Journal of Agricultural and Food Chemistry, 2010, 59, 6113-6119.
- Yu, H. L., Li, J.; Shi, K.; Huang, Q. R. 2011 "Structure of Modified epislon-Polylysine Micelles and Their Application in Improving Cellular Antioxidant Activity of Curcuminoids." Food and Function, 2011, 2, 373-380.
- Yang, X. Q.; Tian, H. X.; Ho, C. T.; and Huang, Q. R. 2012 "Inhibition of Citral Degradation by Oil-in-Water Nanoemulsions Combined with Antioxidants, Journal of Agricultural and Food Chemistry," 59, 6113-6119.
- Yang, X. Q.; Tian, H. X.; Ho, C. T.; and Huang, Q. R. "Stability of Citral in Emulsions Coated with Cationic Biopolymer Layers, Journal of Agricultural and Food Chemistry," 2012, 60, 402-409.
- Losada-Barreiro, S.; Paz, V. S., Bravo-Diaz, C., Martins, F. P., Romsted, L. S. 2012 "Temperature and Emulsifier Concentration Effects on Gallic Acid Distribution in a Model Food Emulsion." Journal of Colloid and Interface Science, in press.
- Romsted, L. S. "Introduction to Surfactant Self-Assembly," in Supramoleular Chemistry from Molecules to Nanomaterials, Gale, P. A., Steed, J. W., Eds., John Wiley & Sons, Chichester, UK, Vol. 1, 2012, pp. 181-204.
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Progress 09/01/09 to 08/31/10
Outputs
OUTPUTS: Hydrophobically modified -polylysine graft copolymers, which were amphiphilic molecules from EPL and denoted as OSA-g-EPL(s), were synthesized by reacting EPL with octenyl succinic anhydride (OSA). The success of synthesis was confirmed by 1H NMR and FT-IR spectroscopy. It was found that OSA-g-EPL(s) had glass transition temperatures lower than EPL. Furthermore, they were able to form polymer micelles in water and to lower the surface tension of water, confirming their amphiphilic properties. The antimicrobial activities of OSA-g-EPL(s) were also examined, and the minimum inhibitory concentrations of OSA-g-EPL(s) against Escherichia coli (E.coli) O157:H7 remained the same as that of EPL. Therefore, OSA-g-EPL(s) have the potential of becoming bi-functional molecules, which can be used either as surfactants/emulsifiers in the encapsulation of nutraceuticals/drugs or as antimicrobial agents. A new chitosan-based amphiphile, octanoyl-chitosan-polyethylene glycol monomethyl ether (acylChitoMPEG), was also prepared using both hydrophobic octanoyl and hydrophilic polyethylene glycol monomethyl ether (MPEG) substitutions. The success of synthesis was confirmed by FT-IR and 1H NMR spectroscopy. The synthesized acylChitoMPEG exhibited good solubility in either aqueous solution or common organic solvents such as ethanol, acetone, and CHCl3. The self-aggregation behavior of acylChitoMPEG in solutions was studied by a combination of pyrene fluorescence technique, dynamic light scattering, atomic force microscopy, and small-angle x-ray scattering (SAXS). The critical aggregation concentration (CAC) and hydrodynamic diameter were found to be 0.066 mg/mL and 24.4 nm, respectively. SAXS results suggested a coiled structure of the triple helical acylChitoMPEG backbone with the hydrophobic moieties hiding in the center of the backbone, and the hydrophilic MPEG chains surrounding the acylChitoMPEG backbone in a random Gaussian chain conformation. Cytotoxicity results showed that acylChitoMPEG exhibited negligible cytotoxicity even at the concentration as high as 1.0 mg/mL. PARTICIPANTS: People involved in this project: Xiaoqing Yang, Huaixiang Tian, Hailong Y TARGET AUDIENCES: Researchers in universities, food industry, and government laboratories. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Improving the stability of citrus flavors (i.e., citral) in low pH beverages has challenged food industry for decades, and is a long-standihang industry need. To address this problem, a novel approach combining the use of antioxidants and nano- and micro-encapsulation technology has been developed. The pseudophase model has been combined with electrochemical and spectrometric methods, as well as PFGSE-NMR to investigate antioxidant distribution in biopolymer micelles, nano- and micro-emulsions. The effects of antioxidant distribution on citral stability will be obtained. This multidisciplinary project will benefit not only the food/beverage, but also the pharmaceutical and cosmetic industries, and provide added value by extending shelf life and preventing oxidation/hydrolysis.
Publications
- (1) Yu, H. L.; Huang, Y. P.; Huang, Q. R. (2010) Synthesis and Characterization of Novel Antimicrobial Emulsifiers, J. Agr. Food Chem., 58, 1290-1295. (2) Huang, Y. P.; Yu, H. L.; Guo, L.; and Huang, Q. R. (2010) Structure and Self-Assembly of a New Chitosan-Based Amphiphile, J. Phys. Chem. B., 114, 7719-7726.
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