Source: RUTGERS UNIVERSITY submitted to
DEVELOPMENT OF NEW STRATEGIES TO ENCAPSULATE AND STABILIZE CITRUS FLAVORS (CITRAL)
 
PROJECT DIRECTOR: Romsted, L. S. Huang, Q. Ho, C. T.
 
PERFORMING ORGANIZATION
Food Science
RUTGERS UNIVERSITY
NEW BRUNSWICK,NJ 08903
 
NON TECHNICAL SUMMARY: Improving the stability of citrus flavors (i.e., citral) in low pH beverages has challenged food industry for decades, and is a long-standing industry need. We bring several unique approaches to the proposed research: (a) to use nanoemulsions for beverage applications; (b) to significantly enhance citral stability in emulsions, including nanoemulsions, by slowing the acid catalyzed rearrangements using cationic biopolymeric emulsifiers prepared from ε-poly(lysine); (c) to use a chemical reaction of a specially designed probe that reacts with antioxidants to determine the fraction of the antioxidant in the interfacial region and the relation between antioxidant distribution and efficiency; and (d) to use special nuclear magnetic resonance techniques to estimate the fraction of oil interfacial regions of emulsions composed of food-grade components. We plan to achieve the following objectives: (1) To encapsulate citral in micelles and nanoemulsions formed from cationic hydrophobically-modified ε-poly(lysine) as the emulsifier and to determine the distributions of antioxidants, such as polyphenols like black tea theaflavins by using a special chemical kinetic method to better understand how antioxidant structure affects its efficiency. (2) To characterized physical properties of nano and micro emulsions containing citral prepared by high-speed homogenization and to emulsify natural food oils with food grade emulsifiers. (3) To characterize the effect antioxidant distribution, emulsion sizes, emulsifiers and oils types on the total content of citrus flavor and off flavor products to develop the optimum conditions for citral emulsion preparation and stabilization. The results should provide more meaningful scales of antioxidant efficiency in emulsions composed of food grade components that will benefit not only the food/beverage industry, but also pharmaceutical and cosmetic industries, and provide added value by extending shelf life, preventing oxidation/hydrolysis, and improving handling characteristics.
 
OBJECTIVES: The overall goal of this proposal is to develop new strategies to encapsulate and stabilize flavors that have challenged food industry for decades, such as citrus flavor (citral). To achieve this goal, a novel approach that unites the use of antioxidants and nano- and micro-encapsulation technology is proposed. The pseudophase model will be 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 evaluated by gas chromatography. 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. We plan to accomplish the following objectives: (a) develop the optimal combination of encapsulation and stablization of citral in hydrophobized, cationic ε-poly(lysine) micelles using a variety of antioxidants; (b) formulate and prepare nano- and micro- O/W emulsions with a variety of oils, food emulsifiers, at pH 2-3 to determine their effectiveness at stabilizing citral; (c) characterize the physical properties of these emulsions by a number of physical methods; (d) determine the distributions of a variety of antioxidants using an established method based on the pseudophase kinetic model; and (e) characterize the stability of citral containing emulsions during storage at 45 ˚C. Effects of antioxidant distribution, emulsion sizes, emulsifiers and oils types on the total content of citral and off flavor products will be studied.
 
APPROACH: Our methods include: (1) Formulating the O/W emulsions with sizes ranging from nanometer to micrometer through a combination of high speed and high pressure homogenization processes. The oils selected include striped MCT, sunflower oil, and corn oil; whereas the emulsifiers selected will include Tween and Span series emulsifiers. When citral emulsions are prepared, ~100 ppm citral oil will be incorporated in the oil phase. The pH of the aqueous phase will be buffered at pH 2.0. (2) Measuring the physical properties of these emulsion systems by dynamic light scattering, rheology, pulsed-field gradient NMR. (3) Determining the fraction of theaflavins in the emulsions between the oil, aqueous and droplet surface by using an established kinetic method based on the pseudophase model that provides values of the partition constants for an antioxidant between the oil and emulsifier surface and aqueous and emulsifier surface regions from the changes in the rate of reaction of the antioxidant with an arenediazonium ion. These results will provide information on the relation between the distributions of theaflavins and their efficiencies. (4) Characterizing citral flavor profiles of citral emulsions during storage at 45 ˚C using gas chromatography. The effects of antioxidant distribution, emulsion sizes, emulsifiers and oils types on the total contents of citrus flavors and off flavor products will be investigated, and the optimum condition for citral emulsion will be identified.
 
CRIS NUMBER: 0219422 SUBFILE: CRIS
PROJECT NUMBER: NJ10906 SPONSOR AGENCY: NIFA
PROJECT TYPE: AFRI COMPETITIVE GRANT PROJECT STATUS: NEW MULTI-STATE PROJECT NUMBER: (N/A)
START DATE: Sep 1, 2009 TERMINATION DATE: Aug 31, 2012

GRANT PROGRAM: IMPROVING FOOD QUAILITY
GRANT PROGRAM AREA: Value Added Products

CLASSIFICATION
Knowledge Area (KA)Subject (S)Science (F)Objective (G)Percent
501501020002.1100%

CLASSIFICATION HEADINGS
KA501 - New and Improved Food Processing Technologies
S5010 - Food
F2000 - Chemistry
G2.1 - Expand Domestic Market Opportunities


RESEARCH EFFORT CATEGORIES
BASIC 60%
APPLIED 30%
DEVELOPMENTAL 10%

KEYWORDS: encapslating flavor~citral stabilization~beverage emulsions~micro encapsulation~poly(lysine)~nano emulsion~micro emulsion~antioxidant distributions~pseudophase kinetic model~electrochemistry~chemical kinetics~food antioxidants~polyphenols~pfgse-nmr~food oils~emulsifiers~arenediazonium ion~dynamic light scattering~rheology~gas chromotography

PROGRESS: Sep 1, 2009 TO Aug 31, 2010
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.

IMPACT: 2009-09-01 TO 2010-08-31 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.

PUBLICATION INFORMATION: 2009-09-01 TO 2010-08-31
(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.

PROJECT CONTACT INFORMATION
NAME: Romsted, L. S.
PHONE: 732-445-3639
FAX: 732-445-5312