University of Massachusetts Amherst ScholarWorks@UMass Amherst Masters Theses Dissertations and Theses February 2016 Fish Oil Nanoemulsions: Optimization of Physical and Chemical Stability for Food System Applications Rebecca M. Walker University of Massachusetts Amherst Follow this and additional works at: https://scholarworks.edu/masters_theses_2 Part of the Food Chemistry Commons Recommended Citation Walker, Rebecca M., "Fish Oil Nanoemulsions: Optimization of Physical and Chemical Stability for Food System Applications" (2016).edu/masters_theses_2/313 This Open Access Thesis is brought to you for free and open access by the Dissertations and Theses at ScholarWorks@UMass Amherst. It has been accepted for inclusion in Masters Theses by an authorized administrator of ScholarWorks@UMass Amherst. For more information, please contact scholarworks@library.
Fish Oil Nanoemulsions: Optimization of Physical and Chemical Stability for Food System Applications A Thesis Presented By REBECCA M. WALKER Submitted to the Graduate School of the University of Massachusetts Amherst in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE September 2015 Department of Food Science © Copyright by Rebecca M. Walker 2015 All Rights Reserved Fish Oil Nanoemulsions: Optimization of Physical and Chemical Stability for Food System Applications A Thesis Presented By REBECCA M. WALKER Approved as to style and content by: __________________________________ David Julian McClements, Chair __________________________________ Eric Decker, Member __________________________________ Guodong Zhang, Member __________________________________ Eric Decker, Department Head Department of Food Science ACKNOWLEDGMENTS I would like to thank my advisor, Dr.
McClements, for this wonderful opportunity and his guidance throughout my research. I would also like to thank Dr. Decker for his support and assistance as my research expanded into lipid oxidation. Additionally, I would like to thank Dr.
Zhang for being on my committee and for his input and encouragement. I am very appreciative of the assistance and support from my lab mates, especially Jennifer Komaiko, Cansu Gumus, Gabriel Davidov Prado, and Laura Salvia-Trujillo. A very special thank you to lab manager, Jean Alamad, who was constantly patient and always helpful throughout my research. Lastly, I would like to thank my family and friend for their unwavering love and support throughout my academic career.
iv ABSTRACT FISH OIL NANOEMULSIONS: OPTIMIZATION OF PHYSICAL AND CHEMICAL STABILITY FOR FOOD SYSTEM APPLICATIONS SEPTEMBER 2015 REBECCA M., OREGON STATE UNIVERSITY M., UNIVERSITY OF MASSACHUSETTS AMHERST Directed by: Professor David Julian McClements Emulsion-based delivery systems offer many potential benefits for incorporating omega-3 oils into foods and beverages. Nanoemulsions are emulsion-based delivery systems that are gaining popularity because of their ease of preparation, small particle size, relatively high stability, high bioavailability, and production of optically transparent emulsions. Fish oil (FO) nanoemulsions are potentially more susceptible to lipid oxidation because of their high degree of lipid unsaturation, high surface area of exposed lipids, and greater light penetration. In the first study, spontaneous emulsification, a low- energy method, was used to fabricate FO nanoemulsions.
The influence of surfactant-to- oil-ratio (SOR) on particle size, turbidity, and physical stability was evaluated. Furthermore, the oxidative stability of these nanoemulsions was compared to emulsions produced by microfluidizer, a high-energy method. The effect of particle size and SOR on oxidation was monitored by measuring lipid hydroperoxides and thiobarbituric acid reactive substances (TBARS). Optically transparent nanoemulsions were formed and v maintained physical stability after being held at 37 °C for 14 days.
FO nanoemulsions produced by high- and low-energy methods had similar oxidative stabilities at 55 °C for 14 days. These results demonstrate that spontaneous emulsification can produce fish oil nanoemulsion that are physically stable and oxidize at similar rates as traditionally prepared nanoemulsions, and are therefore potentially suitable for fortification of clear food systems. Additionally, carrier oils can also impact the physical and oxidative stability of FO nanoemulsions. Medium chain triglycerides, lemon oil, and thyme oil were chosen as carrier oils and added to the oil phase at different ratios of FO to carrier oil for emulsions produced by the microfluidizer.
Medium chain triglycerides and lemon oil produced stable FO nanoemulsions but the thyme oil only produced stable FO nanoemulsions at lower concentrations of carrier oil. On the other hand, at FO to carrier oil ratios of 75/25, lemon oil and thyme oil nanoemulsions had high oxidative stability because of natural of their antioxidants. These findings suggest that lemon oil and thyme oil can produce FO nanoemulsions that are physically and chemically stable and can be used for food system fortification. vi TABLE OF CONTENTS Page ACKNOWLEDGMENTS.
v LIST OF TABLES. x LIST OF FIGURES. DEVELOPMENT OF FOOD-GRADE NANOEMULSIONS AND EMULSIONS FOR DELIVERY OF OMEGA-3 FATTY ACIDS: OPPORTUNITIES AND OBSTACLES IN THE FOOD INDUSTRY. Omega-3 fatty acids.
Chemistry and health benefits. Dietary recommendations for LC-PUFA. Characteristics of nanoemulsions. Formulating safe nanoemulsions.
Formulating label-friendly nanoemulsions. Applications of nanoemulsions in foods and beverages. Obstacles to incorporating Omega-3 nanoemulsions in foods. Reaching the RDA.
PHYSICAL AND OXIDATIVE STABILITY OF FISH OIL NANOMEULSIONS PRODUCED BY SPONTANEOUS EMULSIFICATION. Materials and Methods. Low-energy method: Spontaneous emulsification. High-energy method: Microfluidizer.
Post-production alterations of emulsions. Particle size measurements. Thiobarbituric acid-reactive substances (TBARS). Experimental design and data analysis.
Results and discussion. Effect of surfactant concentration on physical stability. Effect of particle size and surfactant concentration on lipid oxidation. Physical stability of emulsions during oxidation.
Oxidative stability of emulsions. INFLUENCE OF CITRUS AND HERB OILS ON FISH OIL NANOEMULSION FORMATION AND OXIDATIVE STABILITY. Materials and Methods. Particle size measurements.
Thiobarbituric acid-reactive substances (TBARS). Total phenolic content. Extraction of phenolic compounds .2 Folin-Ciocatleu assay. Experimental design and data analysis.
Results and discussion. Determination of surfactant concentration. Mean particle diameter. Physical stability of emulsions during oxidation.
SUMMARY AND CONCLUSION. 100 ix LIST OF TABLES Table Page 1. Concentration of constituents in threefold (3x) lemon oil, provided by Citrus & Allied Essences (Lake Success, NY). Comparison of the composition and structure of different nanoemulsions used in the oxidation studies.
All of the emulsions contained the same final level of oil (1 wt%). Key: SE = spontaneous emulsification (Low-energy); MF = Microfluidization (High-energy). 57 x LIST OF FIGURES Figure Page 1. A schematic diagram comparing the appearance and particle size of emulsions and nanoemulsions.
Nanoemulsions appear transparent because the particle size is smaller than the wavelength of light and so they only scatter light weakly. Proposed mechanism of lipid oxidation in an oil-in-water emulsion or nanoemulsion. Key: PUFA, polyunsaturated fatty acid; ROOH, lipid hydroperoxide; RO, alkyl radicals; L·, lipid radical; LOO-, lipid radical. Comparison of lipid peroxide formation in salmon oil nanoemulsions (mean diameter = 200 nm) stabilized by Brij 76 and Brij 700.
Samples were stored at pH 7. Graph replotted from Silvestre, Chaiyasit, Brannan, McClements and Decker (92). Comparison of EPA and DHA absorption in the intestinal tract of rats when delivered as nanoemulsions (mean diameter = 82 nm) or conventional emulsions (mean diameter = 1580 nm). Volume percentage of the emulsion absorbed was measured at three time intervals.
*Mean values were significantly different (P<0. Graph replotted from Dey, Ghosh, Ghosh, Koley and Dhar (122). Comparison of the mean baseline adjusted percentage blood fatty acid levels for DHA after subjects consumed algal oil delivered in either nanoemulsions or bulk oil incorporated into yogurt. *Mean values were significantly different (P<0.
Graph replotted from Lane, Li, Smith and Derbyshire (81). Influence of surfactant-to-oil ratio (SOR) on the mean particle diameter of oil-in-water emulsions produced by spontaneous emulsification (SE) (A) after being held at 14 °C for 14 days and (B) on day 14 at all temperatures. All systems were made with a total oil phase content of 10% wt (50% fish oil (FO) and 50% lemon oil (LO)) and were diluted to 1% wt total oil phase before measurement. Particle sizes on day 0 were measured immediately after producing the emulsion.
Influence of SOR on the particle size distribution of oil-in-water emulsions produced by SE held at 20 °C on day 14. All systems were made with a total oil phase content of 10% wt (50% FO and 50% LO) and were diluted to 1% wt total oil phase before measurement. Influence of SOR on the turbidity of oil-in-water emulsions produced by SE (A) after being held at held at 20 °C for 14 days and (B) on day 14 at all temperatures. All systems were made with a total oil phase content of 10% wt (50% FO and 50% LO) and were diluted to 1% wt total oil phase before measurement.
Turbidity on day 0 was measured immediately after producing the emulsion. Influence of SOR on the appearance of oil-in-water emulsions produced by SE (A) on day 0 at 20 °C and (B) on day 14 held at 37 °C. All systems were made with a total oil phase content of 10% wt (50% FO and 50% LO) and were diluted to 1% wt total oil phase before measurement. Images on day 0 were taken immediately after producing the emulsion.
Effect of (A) SOR and (B) added surfactant on mean particle diameter for emulsions made by MF and SE and held at 55 °C with added iron. All emulsions were diluted to 1% wt total oil phase. Microscopic images of emulsions made by MF and SE methods and held at 55 °C with added iron at (A) day 0 and (B) day 14. (C) shows enlarged sections of abnormalities found in the emulsions on day 14.
All emulsions were diluted to 1% wt total oil phase. Images were taken at 60x magnification. The black bars at the bottom of each picture are the scales for 10 µm. Effect of (A) particle size and (B) surfactant on hydroperoxide values for emulsions made by MF and SE methods and held at 55 °C with added iron for 14 days.
All emulsions were diluted to 1% wt total oil phase. Effect of (A) particle size and (B) surfactant on TBARS for emulsions made by MF and SE methods and held at 55 °C with added iron for 14 days. All emulsions were diluted to 1% wt total oil phase. Effect of surfactant concentration on mean particle diameter of fish oil nanoemulsions with 5% wt total oil phase (50% wt FO and 50% wt medium chain triglyceride).
Effect of fish oil to carrier oil ratio on mean particle diameter after production (day 0). X/Y indicates the % Fish oil (FO)/% Carrier oil that made up the total oil phase. Key: MCT: medium chain triglyceride; LO: lemon oil; TO: thyme oil. Effect of fish oil to carrier oil ratio on polydispersity index (PDI) after production (day 0; A) and on day 28 (B).
No PDI data available for 0/100 TO as it was measured using static light scattering. X/Y indicates the % FO/% Carrier oil that made up the total oil phase. Key: MCT: medium chain triglyceride; LO: lemon oil; TO: thyme oil. Effect of fish oil to carrier oil ratio on particle size distribution after production (day 0) for MCT (A), LO (B), and TO (C).
X/Y indicates the % fish oil/% carrier oil that made up the total oil phase. Key: MCT: medium chain triglyceride; LO: lemon oil; TO: thyme oil. Images of emulsions made by microfluidization with different fish oil to carrier oil ratios on (A) day 0 (after production) and (B) day 28. X/Y indicates the % fish oil/% carrier oil that made up the total oil phase.
Key: MCT: medium chain triglyceride; LO: lemon oil; TO: thyme oil. Lipid hydroperoxides of fish oil nanoemulsions made with different carrier oils at a ratio of 75/25 fish oil to carrier oil after being held at 20 °C for 42 days. Key: MCT: medium chain triglyceride; LO: lemon oil; TO: thyme oil. TBARS of fish oil nanoemulsions made with different carrier oils at a ratio of 75/25 fish oil to carrier oil after being held at 20 °C for 42 days.
Key: MCT: medium chain triglyceride; LO: lemon oil; TO: thyme oil.