Research Project: Improving Quality, Stability, and Functionality of Oils and Bioactive Lipids

Location: Functional Foods Research

2020 Annual Report

Objectives
Objective 1. Enable new methods using organogels and alternative oil structuring agents to generate commercial zero trans fat, low saturated fat margarines, shortenings, confectionary fats, and other lipid ingredients. Sub-Objective 1.A. Investigate and optimize the physical, rheological, and sensory properties of edible organogels. Sub-objective 1.B. Evaluate the effect of organogels on the properties of structured fats composed of either modified fatty acid composition vegetable oils or fully hydrogenated soybean or cottonseed oil with vegetable oils. Objective 2. Enable new commercial delivery systems using natural antioxidant technologies to protect frying oils, polyunsaturated oils, and bioactive lipids. Sub-Objective 2.A. Evaluate the activity of naturally occurring antioxidants and antioxidant combinations for protection of frying oils and fried foods. Sub-objective 2.B. Evaluate antioxidants or natural antioxidant extracts for protection of polyunsaturated and omega-3 oils and bioactive lipids. Sub-objective 2.C. Investigate new delivery systems for antioxidants, omega-3 oils, and bioactive ingredients. Objective 3. Quantitate and evaluate bioactive ingredients including antioxidants and bioactive lipids in commodity and non-commodity crops as well as in food and agricultural waste processing streams.

Approach
In order to tackle health issues facing the nation including obesity, heart disease, and diabetes, nutritional experts are urging U.S. consumers to limit their consumption of both saturated fats and trans fats from hydrogenated oils, and to eat a diet high in fruits, vegetables, and whole grains, in order to obtain the added benefits of the bioactive food constituents found in these foods. Food manufacturers, restaurants and bakeries are looking for alternatives to hydrogenated vegetable oils or imported palm oil that have the stability necessary for frying, or the functionality needed for margarines and shortenings. U.S. commodity vegetable oils are low in saturated fats and high in healthy polyunsaturated and monounsaturated fats. However, without hydrogenation, the majority of these oils are not stable enough for frying and do not have the proper functionality for margarines and shortenings. The first objective of this project plan is to develop alternative methods of structuring oils in order to solve the problem of functionality for margarine and shortening applications. Low concentrations of natural, inexpensive ingredients, will be used to form organogels with liquid oils. Physical and rheological characteristics of organogels will be fully investigated and test margarines and shortenings will be developed from organogels with desirable physical and rheological properties. These will be further tested in food applications for creaming, aerating, and structuring ability, as well as sensory quality. The second objective of this plan is to develop natural antioxidant systems to protect polyunsaturated fats and bioactive lipids from oxidation and degradation in frying and in food systems, in order to extend the shelf-life and healthfulness of lipids and foods, and to replace synthetic antioxidants. Antioxidants will be tested for activity in commodity oils during frying, in order to extend the fry life and prevent oxidation products from forming. Potential antioxidants will also be tested for their ability to extend the oxidative stability and shelf life of model food systems, such as in oil-in-water emulsions, and in whole grain food products. The potential antioxidants will also be compared to synthetic antioxidants. The third objective of this research is to analyze byproducts of food and agricultural processing for valuable bioactive lipids and/or antioxidants, in order to develop new ingredients from these products, and to reduce waste. Spent coffee grounds, blueberry pomace, and various pulse processing fractions will be extracted and analyzed for bioactive lipids and water soluble antioxidants.

Progress Report
This is the final report for Project 5010-44000-052-00D which has been replaced by new Project 5010-44000-054-00D, "Increasing Food Shelf-Life, Reducing Food Waste, and Lowering Saturated Fats with Natural Antioxidants and Oleogels." Research under Objective 1 has focused on development and characterization (physical, chemical, and sensory) of oleogels as replacements for oils high in saturated fats or trans fats for use in margarines, shortenings, confectionary fats, and other ingredients. The minimum percentage of oleogelator needed for gelation, gel firmness, elasticity, melting and crystallization properties, solid fat content over a range of temperatures, and crystal morphology were determined for oleogels made with natural waxes such as beeswax, candelilla wax, carnauba wax, rice bran wax, and sunflower wax, for food-grade emulsifiers such as stearyl lactylate and monostearin, and for binary combinations of two waxes or wax-emulsifier mixtures. These properties were dependent on the concentration, composition, presence of impurities, and the interaction between chemical components upon crystallization. The impact of vegetable oil composition on properties of oleogels was also investigated using 2.5% to 10% oleogelator with a vegetable oils of varying fatty acid and polar lipid compositions, including modified composition high stearic acid soybean oil, in collaboration with ARS scientists in Columbia, Missouri. These studies provided valuable information about the compositional and concentration effects of oleogelators, oleogelator mixtures, and oil fatty acid and polar compounds on the physical properties of oleogels, allowing the tailoring of oleogel properties. Feasibility of oleogels as solid fat replacement were tested in test margarines and in baking applications as replacement for commercial margarines and shortenings. Cookies which used an oleogel instead of commercial margarine had similar texture and dough spread during baking, while reducing saturated fat content. Up to 25% of shortening was replaced with an oleogel without significantly compromising texture and cake volume and reducing the saturated fat content in the cakes by up to 13.3%. We found that 0.5 -1.5% of sunflower wax, rice bran wax, or candelilla wax could replace hydrogenated oils in peanut butter and other nut and seed-based spreads to bind excess oil. Sensory properties were investigated using a trained descriptive panel to determine wax types and concentrations that imparted texture and flavor similar to hydrogenated cottonseed oil. Oleogels with increasing wax concentration were shown to slow oxidation of encompassed fish oils, which was shown to be dependent on wax type and concentration. This demonstrated that oleogels have potential for delivery of fish oils and bioactive lipids (omega-3 fatty acids) in oxidatively unstable food environments. This fiscal year, research focused on further development and optimization of oleogel properties. After previously identifying binary wax (candelilla and beeswax) oleogels that displayed increased firmness but eutectic melting properties, margarines were made with these mixtures. Margarines (spreads) containing 3, 5, and 7% wax mixtures in place of conventional solid fats had lower melting point and higher gel strength. Spreads with firmness similar to commercial spreads could be achieved with less than 3% wax, but the firmness of commercial stick margarines could not be achieved with as much as 7% wax. The melting point of margarines can be tailored by changing the ratio of two waxes. The second objective of this plan is to develop natural antioxidant systems to protect polyunsaturated fats and bioactive lipid from oxidation and degradation in frying and in foods in order to replace synthetic antioxidants. It was demonstrated that sesamol, a natural lignin originating from sesame oil, prevented oxidation of fish oil during storage, offering an inexpensive, food label friendly alternative to synthetic antioxidants for the protection of omega-3 oils. Corn phytosteryl ferulates were found to protect soybean oil during frying and to improve the shelf-life of chips that absorbed the oil and antioxidant. We also found that corn fiber oil, which contains 10% phytosteryl ferulates, blended with soybean oil at a level of 1% could improve the frying life as well as shelf-life of the fried food. A sample of corn fiber extract was sent to a snack food manufacturer for testing in their pilot facility under a material transfer agreement. Amino acids and peptides are known to have antioxidant activity, but they had never been tested in frying oil. Hydrophobic amino acids, and those that include a thiol, thioether, or extra amine groups, such as arginine, cysteine, lysine, methionine, and tryptophan, had stronger antioxidant activity in frying oil than tert-butylhydroquinone (TBHQ), the most common synthetic antioxidant used in frying. The mechanism is partially due to synergism with tocopherols that are present in frying oils and correlated with radical scavenging activity. This fiscal year we focused on increasing commercial feasibility by combining with other natural antioxidants that are widely used in foods but are ineffective in frying oils. In addition, antioxidant activity of methionine was verified in six additional vegetable oils including sunflower, peanut, corn, canola, olive, and high oleic soybean oils. Spent coffee grounds (SCG) from a commercial flavor company were extracted using different solvents, and the antioxidant activity was evaluated in soybean and fish oil during storage at two temperatures. Acetone extract of de-oiled SPG had the best antioxidant activity, as effective as butylated hydroxytoluene (BHT), a commonly used synthetic antioxidant. Extracts from Osage orange fruit had stronger antioxidant activity than tocopherols and a commercial rosemary extract at 0.1% when tested in soybean oil and fish oil during storage at 25°C and 40°C. In addition, 0.1% extract showed comparable antioxidant activity to BHT at its legal limit, 0.02%. Frying is a simple potential vehicle for incorporating bioactive lipids into food products, but the stability of bioactive lipids during frying and storage needs to be tested. Tocotrienols are bioactive antioxidants that are low in the typical U.S. diet. Annatto tocotrienols were added to frying oil and absorbed by fried foods such as tortilla chips. The tocotrienols also protected the natural tocopherols in soybean oil and extended the shelf-stability of the fried product. In collaboration with researchers at the National Corn-to-Ethanol Research Center, Edwardsville, Illinois; University of Georgia, Athens, Georgia; and Tufts University, Medford, Massachusetts, we determined the effect of different levels of low- and full-fat dried distillers grains (DDGS) in layer hen feeds on layer hen production and egg yolk lipid components. At least 20% DDGS could safely be incorporated into the feed with no negative impact on layer hen health and egg production and DDGS incorporation increased the levels of tocopherols, tocotrienols, and carotenoids in the egg yolk, improving egg color and content of these bioactive lipids. The third research objective is to quantitate and evaluate bioactive ingredients including antioxidants and bioactive lipids in commodity and non-commodity crop and agricultural waste streams. We developed various solvent extracts of corn fiber, spent coffee grounds, blueberry pomace from a commercial blueberry juice processor, as well as Osage orange fruit extracts, which have been tested for application in frying and protection of vegetable oils and fish oils under Objective 2. Corn fiber hexane extracts showed the most promise for frying applications, and samples have been sent to several companies for testing frying performance at pilot scale. SCG and Osage orange extracts had comparable performance to BHT in storage studies to improve oxidative stability of soybean and fish oil. SCG are currently discarded in landfills. Osage orange trees grow extensively throughout the midwestern and southwestern regions of the United States, and the fruits from these trees are underutilized, despite high content of osajin and pomiferin, two potent antioxidants that also have potential pharmaceutical applications. In collaboration with ARS scientists in Peoria, Illinois, working on pulse processing, we demonstrated that antioxidant content notably increased in black bean flours subjected to jet-cooking under acidic conditions. Along with the goal of improving physical and sensory properties through different processing conditions, increasing the antioxidant activity of the flours may increase their value as food ingredients. In collaboration with ARS scientists in Peoria, Illinois, we developed a method for evaluating the odor-reducing properties of cat litters formulated with agricultural waste streams, including red cedar wood chips and soybean hulls. We also collaborated with an equipment manufacturer for the corn-ethanol industry to determine the average content and variability in phenolics, bioactive lipids including tocopherols, tocotrienols, carotenoids, phytosterols, as well as the antioxidant activity of distillers grain oil (DGO) samples from 50 corn ethanol plants. Knowledge of the content and variability of bioactive lipids in these oils can assist the industry in determining its nutritional value as a feed supplement and for other potential value-added applications, such as a supplemental source of lutein and zeaxanthin. The research conducted over the past five years has resulted in 33 peer-reviewed publications, book chapters, and review articles, as well as, one Cooperative Research and Development Agreement, one Cooperative Research Agreement (trust fund agreement), one incoming Material Transfer Research Agreement, two outgoing Material Transfer Agreements, and one invention disclosure.

Accomplishments
1. Natural antioxidants to improve frying oil quality. Frying oil rapidly degrades due to the high temperatures used which accelerate lipid oxidation. ARS scientists in Peoria, Illinois, demonstrated that several amino acids might be effective replacements for synthetic antioxidants that are used to prevent or slow these reactions. These scientists studied the antioxidant interaction at frying temperatures of methionine with commercial natural antioxidants including rosemary extract, green tea extract, epigallocatechin (the major component of green tea extract) and ascorbic acid. While it was determined that the interaction of these two amino acids was either additive or antagonistic with the studied antioxidants, the studies reinforced previous findings that amino acids interact synergistically with natural tocopherols found in vegetable oils. In addition, antioxidant activity at frying temperature was verified in six other vegetable oils besides regular soybean oil, including sunflower, peanut, corn, canola, olive, and high oleic soybean oils. This knowledge will be used by ingredient suppliers and oil processors to formulate effective antioxidants for frying oil applications and frying oils with higher stability to frying. More effective antioxidants for frying will also result in healthier fried foods with longer shelf-life, while reducing saturated fat consumption, which can positively impact consumer health. This also benefits commodity oilseed (soybean, sunflower, canola) and corn growers and reduces cost and waste for restaurants and food manufacturers.

2. Identification of frying oil degradation compounds. During frying there are significant polymerization reactions in the oil, resulting in high levels of polymers that may be associated with adverse health effects, and which also require significant investment of time and cleaning to remove from frying equipment. The chemical bonds that form during polymerization have not been well understood. ARS scientists in Peoria, Illinois, used nuclear magnetic resonance (NMR) to discover ester bonds were responsible for the polymerization of soybean oil during frying and heating at 175°C. The reaction of oxidized oil with acetyl chloride followed by NMR study also verified there were no ether bonds and identified the formation of alcohols. This research helps to better understand oxidation products and oxidation mechanisms that occur during frying, which can assist in developing methods to mitigate these reactions to improve fry-life and reduce cleaning costs for restaurants and manufacturers. This research benefits commodity oilseed (soybean, sunflower, canola, cottonseed) and corn growers as well as vegetable oil processors.

3. Wax combinations to replace saturated fats in food. Using relatively low concentrations (0.5-5%), melted waxes can cool in vegetable oil to form crystalline networks, or oleogels, which bind liquid oil to form continuous semi-solids that are similar to palm oil or hydrogenated oils. There is increased interest in using oleogels as alternatives to partially hydrogenated oils and saturated fats in foods. While much is known about the properties of oleogels made with a single wax component, there is little information about how waxes with different compositions will interact and how the interaction between waxes in oleogels will affect their physical properties. ARS scientists in Peoria, Illinois, characterized the melting and crystallization properties of 30 binary mixtures of beeswax, sunflower wax, and candelilla wax, along with the physical properties of oleogels made with the wax mixtures. Each wax combination had unique melting and crystal size and shape in the oleogels, and some combinations were found to have lower melting point yet a firmer texture, which is desirable for some food applications such as margarines and shortenings. This research will assist in developing healthier food products that are lower in saturated fats using commodity oils grown by U.S. commodity oilseed (soybean, sunflower, canola) growers.

Review Publications
Hwang, H., Winkler-Moser, J.K., Liu, S.X. 2019. Study on antioxidant activity of amino acids at frying temperatures and their interaction with rosemary extract, green tea extract, and ascorbic acid. Journal of Food Science. 84(12):3614-3623. https://doi.org/10.1111/1750-3841.14963.
Winkler-Moser, J.K., Hwang, H.-S., Kerr, B.J. 2020. Changes in markers of lipid oxidation and thermal treatment in feed-grade fats and oils. Journal of the Science of Food and Agriculture. 100(8):3328-3340. https://doi.org/10.1002/jsfa.10364.
Winkler-Moser, J.K., Anderson, J.A., Byars, J.A., Singh, M., Hwang, H. 2019. Evaluation of beeswax, candelilla wax, rice bran wax, and sunflower wax as alternative stabilizers for peanut butter. Journal of the American Oil Chemists' Society. 96(11):1235-1248. https://doi.org/10.1002/aocs.12276.
Vaughn, S.F., Moser, J.K., Berhow, M.A., Byars, J.A., Liu, S.X., Jackson, M.A., Peterson, S.C., Eller, F.J. 2020. An odor-reducing, low dust-forming, clumping cat litter produced from Eastern red cedar (Juniperus virginiana L.) wood fibers and biochar. Industrial Crops and Products. 147. Article 112224. https://doi.org/10.1016/j.indcrop.2020.112224.
Winkler-Moser, J.K., Anderson, J., Felker, F.C., Hwang, H.-S. 2019. Physical properties of beeswax, sunflower wax, and candelilla wax mixtures and oleogels. Journal of the American Oil Chemists' Society. 96(10):1125-1142. https://doi.org/10.1002/aocs.12280.
Hwang, H.-S. 2020. A critical review on structures, health effects, oxidative stability, and sensory properties of oleogels. Biocatalysis and Agricultural Biotechnology. 26:101657. https://doi.org/10.1016/j.bcab.2020.101657.
Hwang, H.-S., Ball, J.C., Doll, K.M., Anderson, J.E., Vermillion, K. 2020. Investigation of polymers and alcohols produced in oxidized soybean oil at frying temperatures. Food Chemistry. 317:126379. https://doi.org/10.1016/j.foodchem.2020.126379.
Chrysan, M.M., Hwang, H.-S. 2020. Margarines and spreads. In: Shahidi F., editor. Bailey’s Industrial Oil and Fat Products. 7th Edition. Hoboken, NJ: Wiley Publishers. https://doi.org/10.1002/047167849X.bio036.pub2.
Malcolmson, L.J., Winkler-Moser, J.K. 2020. Flavor and sensory aspects. In: Shahidi, F., editor. Bailey’s Industrial Oil and Fat Products. 7th Edition. Hoboken, NJ: Wiley Publishers. https://doi.org/10.1002/047167849X.bio032.pub2.
Kenar, J.A., Felker, F.C., Singh, M., Byars, J.A., Berhow, M.A., Bowman, M.J., Moser, J.K. 2020. Comparison of composition and physical properties of soluble and insoluble navy bean flour components after jet-cooking, soaking, and cooking. LWT - Food Science and Technology. 130. Article 109765. https://doi.org/10.1016/j.lwt.2020.109765.