Location: Functional Foods Research
2022 Annual Report
Objectives
Objective 1. Stabilize sensitive and bioactive food ingredients, improve shelf-life, and reduce food waste with optimized natural antioxidants and plant extracts.
Sub-Objective 1.A. Evaluate antioxidant activity of combinations of antioxidants in frying oils and fried foods.
Sub-objective 1.B. Evaluate antioxidants or natural antioxidant extracts for protection of polyunsaturated and omega-3 oils and bioactive lipids and to extend shelf-life of whole foods and food ingredients.
Objective 2. Enable oleogel applications to reduce saturated fats in foods.
Sub-Objective 2.A. Investigate and optimize the physical and sensory properties as well as the oxidative stability of edible oleogels.
Sub-objective 2.B. Evaluate interesterified natural waxes, waxes with vegetable oils, fatty alcohols or fatty acids, as potential new oleogelators.
Objective 3. Improve commercial value and sustainable food production through recovery of healthful bioactive ingredients from food processing by-products or waste.
Approach
Approximately 30% of the food supply in the United States is wasted and the worldwide problem is even larger. This waste represents a large strain on the environment and on the entire food production enterprise. According to the Food and Drug Administration (FDA), about 20% of the food waste in the United States is due to confusion about the meaning and safety of foods labeled with “best before” and “use by” dates. This means that extending shelf-stability of foods can have an impact in reducing food waste. There is also concern about the healthfulness of processed foods, including the high content of saturated fats, which consumers are advised to limit in the diet. However, reducing the saturated fat content of foods by substituting with healthier fats can influence product texture and mouthfeel, as well as the oxidative stability and shelf-life. The research of the next five years will enable the commercial development of natural antioxidants needed to improve the oxidative stability and shelf-life of foods formulated with a lower saturated fat content. Antioxidants will improve the stability of frying oils, fried foods, and high-value foods such as nuts and protein replacement bars. Oleogels will be developed with improved physical and melting properties for margarines and shortenings and other food applications that require hard fats and will have lower amounts of saturated fats and zero trans fats. New value-added ingredients such as antioxidants and bioactive lipids will be mined and characterized from low-value agricultural inputs. This research, together with complimentary technology and policy development strategies, will contribute to efforts to reduce food waste and improve the healthfulness of the food supply.
Progress Report
Sub-objective 1.A. is to evaluate the antioxidant activity of combinations of antioxidants in frying oils and fried foods. The overall goal of this sub-objective is to develop synergistic antioxidant combinations that can be used to improve frying oil life as well as the shelf-life of fried foods. The 24-month milestone was to have completed screening mixtures of antioxidants for shelf-life improvement. We started with screening tests using a small-scale protocol that we had previously developed. However, this was producing inconsistent results and could not be adapted to produce enough product for shelf-life analysis, so we altered the research flow to instead develop frying and shelf-life protocols for scaled up studies, originally scheduled as the 36-month milestone. These were found to be adaptable for screening studies as well. Sweet potato chips, which are a good source of beta-carotene, a pro-vitamin A carotenoid, were chosen as a model food product so that the effects of antioxidants on shelf-life can be evaluated wholistically to include texture, nutritional value, and changes due to co-oxidation of the oil, beta-carotene and carotenoids, as well as proteins. We performed shelf-life studies under moderate (35 degrees C) as well as accelerated conditions (45 degrees C), and headspace volatiles were measured to identify the key chemical compounds that either developed (oxidation products) or degraded (sweet potato flavor compounds) during storage. Procedures for testing the crispness of chips over time, color, near-infrared analysis, moisture content, total fat content, surface and penetrated oil content, chip tocopherol and carotenoid contents were all determined. This has driven progress towards large-scale studies forward and was found to be adaptable for the screening studies as well.
In addition, to develop improved natural antioxidants to replace synthetic antioxidants for frying oils, amino acids, which were previously found to have strong antioxidant activity, were modified by mixing with inorganic bases to produce amino acid salts. The modified versions of amino acids had stronger antioxidant activity than the corresponding amino acids. They were also effective in other vegetable oils including olive, high oleic soybean, canola, avocado, and corn oils. Thus, antioxidant activity of amino acids can be improved by the reaction with an inorganic base. For example, the modified version of phenylalanine at 0.12% more effectively prevented oil oxidation than tert-butyl hydroquinone (TBHQ), a synthetic antioxidant, at its legal concentration limit (0.02%) indicating potential as a new antioxidant for frying.
Sub-objective 1.B. is to evaluate antioxidants or natural antioxidants for protection of polyunsaturated and omega-3 oils and bioactive lipids and to extend shelf-life of whole foods and food ingredients. The goal for this research is to develop antioxidant systems to prevent oxidation and increase shelf-life of bulk oils, emulsions, peanuts and nuts, and/or other foods. Since amino acids had strong antioxidant activity in frying oil, preliminary studies were conducted to evaluate the effect of methionine on soybean oil oxidation and shelf-life under mildly accelerated storage conditions (35 degrees C). Methionine at 0.1, 0.2, and 0.3%, which had the strongest antioxidant activity among other amino acids at frying temperature, did not significantly reduce the oxidation of soybean oil or increase its shelf-life. Thus, it is considered that the mechanism of amino acid antioxidant activity may be related to high-temperature reactions of amino acid that do not occur at a storage temperature.
Sub-objective 2.A. is to investigate and optimize the physical and sensory properties as well as the oxidative stability of edible oleogels. The overall goal of this research is to develop prototype oleogel-based structured fats for use in margarines, shortenings, and nut/seed butters. The 24-month milestone was to develop prototype margarine, spread, shortening or other foods using oleogels, and to conduct preliminary evaluation of physical and functional properties. The milestone was met after 12-months when a paper was published in 2021 on the chemical and physical properties of margarines developed with binary wax combinations. In additional progress towards this objective, work was completed and published on the sensory (flavor and texture) properties of peanut butter stabilized with beeswax, candelilla wax, rice bran wax, and sunflower wax. Several wax types and levels were found to produce peanut butter with similar sensory properties to peanut butter made with conventional stabilizers, which use fully hydrogenated oils to bind the excess oil and alter the texture in peanut butter and other nut/seed spreads. A third study was completed under this sub-objective where margarines were developed with hempseed oil oleogels and the properties were evaluated. Also, in collaboration with scientists at Sejong University (Seoul, Korea), utilization of oleogels with binary oleogelator blends of candelilla wax and glycerol monostearate (GMS), a food-grade monoglyceride, were studied in confectionary fillings. These blends were previously shown to have improved melting and texture properties compared to oleogels with candelilla wax or GMS alone. Of the combinations studied, filling cream made with the 60% candelilla wax and 40% GMS oleogel had similar textural properties to filling cream made with conventional shortening, and the level of saturated fatty acids in the new filling creams was distinctly reduced from 36.2% to 10.3%.
Sub-objective 2.B. is to evaluate interesterified natural waxes, waxes with vegetable oils, fatty alcohols or fatty acids, as potential new oleogelators. The overall goal of this research is to develop new oleogelators with a wider profile of solid fat content, melting, and other physical properties.
The 24-month milestone for this objective was to complete preliminary reactions and composition analysis of reaction products. A preliminary study was conducted for the chemical interesterification of two waxes to improve the physical properties of wax-based oleogels. Chemical interesterification included six combinations of four waxes (beeswax, sunflower wax, rice bran wax, and candelilla wax). The interesterified product with rice bran wax and sunflower wax resulted in soybean oil oleogels with significantly higher firmness than that those with pure wax and with the mixture of two waxes. However, additional repeated experiments found inconsistent results, perhaps due to non-specificity of the chemical interesterification reactions. Therefore, the chemical reaction conditions are being modified to produce consistent products, and enzymatic interesterification methods are also being considered for future research.
Additional research under this sub-objective included a collaboration with ARS researchers in Wyndmoor, Pennsylvania, to evaluate the oleogelation properties of novel fatty alcohols. The preliminary investigations have determined the minimum gelation concentrations for oleogel formation, the thermal properties (melting and crystallization profiles), and microscopic evaluation of the oleogel microstructure.
The goal for Objective 3 is to develop new sources of antioxidants, bioactive lipids, or wax from agricultural processing fractions or coproducts. The 24-month milestones were to improve/optimize extraction of corn fiber and/or corn bran for phytosteryl ferulates and other phenolic antioxidants and to evaluate improved coffee retentate and/or fruit pomace extracts in bulk oils (frying and/or storage studies). As progress towards the first milestone, extractions of corn bran and corn fiber were carried out using different solvent types and temperatures using accelerated solvent extraction to determine best conditions for increasing yield, antioxidant activity, and ferulate phytosterol esters. In addition, wax was extracted from soybean hull crude lipid extracts, and characterized for its main chemical components, and upon scale-up the soybean hull wax will be tested for oleogelation properties.
Research was also conducted to develop methods to improve the antioxidant activity of spent coffee ground (SCG) extracts, which were previously shown to have stronger antioxidant activity than other commercial natural antioxidants in soybean oil and fish oil. We attempted to improve the activity of the SCG extracts by chemical modification, however, the modification only resulted in minor improvement to the antioxidant activity.
Essential oils often contain unique and effective antioxidants, but their strong flavor and odor limits how much that can be used in foods. ARS researchers in Peoria, Illinois collaborated with scientists from University of Putra, in Selangor, Malaysia, and Agricultural University in Faisalabad, Pakistan, to evaluate the antioxidant activity of fractionated and nanoencapsulated essential oils from Indian Blackberry (Syzygium cumini) leaves. By fractionating the essential oils, the chemicals that impart the strong flavor were removed. It was found that less aromatic fractions retained similar antioxidant activity to the volatile fractions. In addition, most of the fractions also maintained antioxidant activity when encapsulated in nanoparticles.
We also collaborated with scientists at University of Illinois in Urbana-Champaign, Illinois, to characterize the lipid content and compositional profile from oil recovered after simultaneous saccharification and co-fermentation of biomass for ethanol production. This research helps to develop methods for producing multiple biofuel feedstocks (biodiesel and ethanol) from a single biomass source.
Accomplishments
1. Demonstrated new natural antioxidants to enable the use of healthier frying oil. During deep fat frying, oil quality is deteriorated by lipid oxidation. Vegetable oils such as soybean oil are high in healthy polyunsaturated fatty acids including omega-3 fatty acids, but these oils quickly deteriorate during frying, reducing their usable fry-life and sometimes producing toxic substances. Therefore, more stable oils such as palm oil and other tropical oils are widely used by the food industry and in restaurants, which can cause many health problems for consumers due to their high content of saturated fats. ARS researchers in Peoria, Illinois, recently reported that certain amino acids can effectively prevent oxidation of vegetable oils such as soybean oil during frying. Their activity was shown to be significantly improved by converting the free amino acids to either sodium or potassium salts. Among the amino acid salts studied, phenylalanine potassium salt had the strongest antioxidant activity, which was demonstrated in oils including soybean, olive, high oleic soybean, canola, avocado, and corn oil. A frying study with potato cubes in soybean oil showed that phenylalanine potassium salt at 0.12% had significantly stronger antioxidant activity than tert-butyl hydroquinone, a widely used synthetic antioxidant for frying oils, at its legal limit (0.02%). This study demonstrated that simple amino acid salts could replace synthetic antioxidants used in frying oils, which would benefit consumers by enabling the use of healthier oils for frying, preventing production of toxic substances, and avoiding the use of potentially toxic synthetic antioxidants. This is of great interest to oil and food companies that seek natural and clean-label alternatives to synthetic antioxidants, and the ability to use U.S. produced vegetable oils rather than imported oils.
2. Utilized hemp seed oil oleogels for healthy margarines. Plant based spreads or so-called “plant butters” are currently surging in the marketplace, in conjunction with other plant-based food and proteins. Conventional solid fats used in margarines and other related products contain high levels of saturated fatty acids, which are known to have negative health effects. Hemp seed oil is high in healthy polyunsaturated fatty acids including omega-3 fatty acids, as well as other substances that have health benefits such as anti- inflammatory activities, blood lipid profile improvement, and protection from oxidative stress. To utilize hempseed oil as a major ingredient in margarine or spread, ARS researchers in Peoria, Illinois, made hemp seed oil oleogels by adding small amounts of melted natural waxes to the liquid oil, which then crystallized upon cooling to form a semisolid network that entrapped the liquid oil. The oleogels were demonstrated to be able to replace solid fats in spreadable margarines. Margarines with the same hardness of commercial margarine spreads were made by adding less than 3% wax. However, the firmness of a stick margarine could not be achieved with up to 7% wax. Depending on whether the desired product is a spreadable margarine or a stick margarine, hemp seed oil oleogels could be used to replace conventional solid fats fully or partially in formulations, thereby reducing the saturated fat content. This information is important for food companies that are seeking to develop healthier spreads by incorporating oils with low levels of saturated fats and healthful bioactive components.
Review Publications
Jia, Y., Kumar, D., Winkler-Moser, J.K., Dien, B.S., Rausch, K., Tumbleson, M.E., Singh, V. 2022. Coprocessing corn germ meal for oil recovery and ethanol production: a process model for lipid-producing energy crops. Processes. 10(4). Article 661. https://doi.org/10.3390/pr10040661.
Kim, M., Hwang, H., Jeong, S., Lee, S. 2021. Utilization of oleogels with binary oleogelator blends for filling creams low in saturated fat. LWT - Food Science and Technology. 155. Article e112972. https://doi.org/10.1016/j.lwt.2021.112972.
Shaheen, R., Hanif, M.A., Nisar, S., Rashid, U., Sajid, Z., Shehzad, M.R., Winkler-Moser, J.K., Alsalme, A. 2021. Seasonal variation, fractional isolation and nanoencapsulation of antioxidant compounds of indian blackberry (Syzygium cumini). Antioxidants. 2021; 10(12). Article 1900. https://doi.org/10.3390/antiox10121900.
Winkler-Moser, J.K., Anderson, J.A., Hwang, H. 2022. Texture and flavor evaluation of peanut butter stabilized with natural waxes. Journal of Food Science. 87(4):1851-1864. https://doi.org/10.1111/1750-3841.16118.
Hwang, H., Winkler-Moser, J.K., Liu, S.X. 2022. Antioxidant activity of amino acid sodium and potassium salts in vegetable oils at frying temperatures. Journal of the American Oil Chemists' Society. 99(5):407-419. https://doi.org/10.1002/aocs.12585.
Hwang, H., Kim, S., Moser, J.K., Lee, S.L., Liu, S.X. 2022. Feasibility of hemp seed oil oleogels structured with natural wax as solid fat replacement in margarine. Journal of the American Oil Chemists' Society. 99(11):1055-1070. https://doi.org/10.1002/aocs.12619.
