Location: Functional Foods Research
2018 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
The first objective of this project plan is to develop organogels (also called oleogels) as alternatives to saturated fats or trans fat-containing partially hydrogenated oils for margarines, spreads, shortenings, and other food applications. In order for oleogels to serve as suitable replacements, it is critical to understand how the physical and sensory properties are influenced by the oleogelator as well as other food ingredients. As progress towards this objective, work conducted in fiscal year 2018 (FY18) was aimed to determine how oil fatty acid composition and other ingredients affect the physical properties of oleogels such as firmness, crystal size and morphology, and melting and crystallization behavior. Conducted experiments with oleogels made from high stearic soybean oils. The higher content of stearic acid created firmer oleogels at refrigeration temperature. However, the firmness of oleogels with high stearic soybean oil at room temperature was similar to regular soybean oil because the higher stearic acid soybean oils also had higher contents of polar components that negatively affected the oleogel firmness. A more detailed study using differential scanning calorimetry (DSC) and solid fat contents analysis (SFC) showed that this was caused by polar compounds interfering with oil crystallization. Wax crystals were shown to facilitate nucleation of oil crystals, so that fat crystals formed at a slightly higher temperature during cooling.
Completed studies on the properties of binary wax mixtures as well as 5% wax oleogels made with mixtures of sunflower wax, candelilla wax, and beeswax. Firmness and melting properties of oleogels were highly influenced by the ratio of the two waxes in the oleogels. In some cases, waxes were found to interfere with each other, and formed softer oleogels. However, several different ratios of waxes were found to result in lower melting properties, but firmer textures, indicating that these properties can be modified by careful selection of oleogelators.
Conducted experiments to evaluate the effect of two common food emulsifiers, glycerol monostearate and palm mono- and diacylglycerols, on wax oleogel gelling properties, firmness, and melting properties. The results of these experiments are still being analyzed and evaluated, and additional experiments will be conducted. In addition, based on the results of binary wax oleogels, several experiments were conducted using ternary wax oleogels with the aim of improving the firmness properties of oleogels while maintaining a lower melting point.
Hydrogenated oils or palm oil are added to commercial peanut butter at levels of = 5% as stabilizers to improve texture and to prevent oil leakage. Therefore, as an application of wax oleogel technology, scientists conducted experiments on the use of beeswax, candelilla wax, sunflower wax, or rice bran wax as a substitute for fully hydrogenated cottonseed oil or palm oil in peanut butter. The oil binding capacity, oil leakage over a six-month period, firmness, and viscosity were evaluated for four levels of each wax type (0.5%-3%). A sensory panel also evaluated the spreadability, mouthfeel, and flavor of the resulting peanut butters. The results indicated that peanut butter samples made with either rice bran wax or sunflower wax functioned similarly to the control in terms of oil binding capability, firmness, and rheology, and had a similar sensory profile to the control.
In order to be commercially viable as replacements for hydrogenated oils or saturated fats, oleogels must also have bland or non-objectionable sensory properties so that they do not cause or interfere with the flavor or aroma of the food product. Experiments were conducted to develop an understanding of the flavor and aroma properties of oleogels formed with waxes. Preliminary experiments with sensory evaluation panelists have indicated that a portion of testers detected objectionable flavors in some wax oleogels at the higher wax addition level. The headspace volatile components in different wax types is being studied to determine the components that contribute to the flavor and aroma of wax-based oleogels. These experiments are ongoing.
The second objective of this project is to develop natural antioxidant systems to protect polyunsaturated fats, including fish oils and frying oils, as well as other bioactive lipids, from oxidation and degradation in frying and in food systems. One of major discoveries last year was the strong antioxidant activity of amino acids during frying. Conducted a study to understand the antioxidant activity of dipeptides (two amino acids linked by a peptide bond). The dipeptides also showed significant antioxidant activity in bulk oil at frying temperatures. In general, the antioxidant activity of a dipeptide was weaker than the activities of the two constituent amino acids alone, although there were some exceptions. Protein hydrolysates are obtained by hydrolysis of animal or plant proteins, which are composed of a variety of peptides. Three different protein hydrolysates were tested under the same conditions and found to be effective antioxidants for frying.
Experiments were also conducted with extracts of spent coffee grounds, the waste material left after coffee brewing. A large amount of spent coffee grounds are produced in the commercial production of instant coffee and coffee flavored ingredients. The spent coffee grounds were extracted with several different solvents and their antioxidant activity was evaluated in soybean and fish oil at two different temperatures to mimic oxidative abuse during storage, transport, or heating. The results indicated that the extraction solvent and separation process influenced the antioxidant activities of the extracts, and that the best extracts had similar protective effect compared to a commercial synthetic antioxidant.
The third objective under this project is to 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. Quantitated antioxidant phenolic compounds and in vitro antioxidant activity of black bean flours that were jet-cooked using different pH conditions. In addition, the composition of bioactive lipid components, total phenolics, and antioxidant activity from oils extracted from distillers grains from corn-to-ethanol plants from 20 plants throughout the Midwest are being analyzed.
Accomplishments
1. Incorporating bioactive lipids into fried foods. Tocotrienols are members of the vitamin E family of lipid compounds, but they are not as well-known as the main vitamin E form: tocopherols. Interest in the benefits of tocotrienols has recently surged, as they have been shown to have antioxidant activity, cholesterol lowering and cardio-protective effects, neuroprotective effects, and to have anticancer and antitumor activities. However, tocotrienols are not prevalent in the typical western diet. ARS researchers in Peoria, Illinois, incorporated tocotrienols from a natural source into frying oil, and were able to show that the tocotrienols were absorbed by fried tortilla chips. In addition, due to their antioxidant effects, the fried tortilla chips with added tocotrienols had better shelf stability and had better flavor after storage. This research is of interest to oil processors and food manufacturers interested in incorporating tocotrienols into food products as functional food ingredients and for extending shelf-life of fried foods using natural ingredients.
2. Oleogels to prevent oil oxidation. Oleogels are liquid oils that are structured into semi-solids using gelators, which are small molecular weight compounds that form a crystalline network that entraps the liquid oil. The properties of oleogels are similar to hard fats such as palm oil and hydrogenated oils, thus oleogels are considered a promising alternative to harmful fats such as trans and saturated fats. One concern regarding replacement of saturated and trans fats with oleogels made with liquid oils, is that liquid oils generally have higher levels of polyunsaturated fatty acids that are more susceptible to oxidation than trans and saturated fats. ARS researchers in Peoria, Illinois, determined the effect of four different wax gelators on the oxidation of fish oil in oleogels stored at 35°C and 50°C to mimic temperature abuse. All waxes protected fish oil from oxidation compared to regular fish oil, although the waxes were less protective at higher temperatures. Higher cooling rates used when making the oleogels resulted in more stable gels, which is likely because of a more tightly packed crystalline network that reduced oxygen diffusion to the oil. Based on their results, the researchers recommend using the minimum amount of wax necessary and higher cooling rates in order to maximize the protective effect. This indicates that the oleogel technology can be used as a method to prevent oxidation of liquid oils, which is currently an especially serious problem during manufacturing, transportation, and storage of omega-3 oil supplements and food products such as fish oil.
3. Oleogels using high-stearic acid soybean oil. Stearic acid does not increase serum total cholesterol, LDL- and HDL-cholesterol levels unlike shorter chain saturated fatty acids such as lauric acid, myristic acid, and palmitic acid. Therefore, soybean breeders have been trying to develop soybean lines that have a higher stearic acid composition in order to replace partially hydrogenated soybean oil that contain harmful trans fatty acids. ARS researchers in Peoria, Illinois and Columbia, Missouri, studied the physical properties of oleogels from high stearic soybean oil, to understand the effect of fatty acid composition of oil and minor ingredients in oil such as polar compounds on the firmness, melting behavior, fluidity, and crystal microstructure. At room temperature, high stearic soybean oils had the same firmness as regular soybean oil oleogels. However, the firmness of high stearic oil oleogels at refrigeration temperature sharply increased due to the high content of stearic acid. It was also found that high stearic acid soybean oils had more polar compounds than regular soybean oil, which negatively affected the firmness of oleogels. This information is valuable for the practical application of oleogel technology to replace hydrogenated oils and tropical fats such as palm oil. It also provides valuable information about the potential applications for high stearic acid soybean oils.
Review Publications
Winkler-Moser, J.K., Bakota, E.L., Hwang, H.-S. 2018. Stability and antioxidant activity of annatto (Bixa orellana L.) tocotrienols during frying and in fried tortilla chips. Journal of Food Science. 83(2):266-274.
Hwang, H.-S., Gillman, J.D., Winkler-Moser, J.K., Kim, S., Singh, M., Byars, J.A., Evangelista, R.L. 2018. Properties of oleogels formed with high-stearic soybean oils and sunflower wax. Journal of the American Oil Chemists' Society. 95(5):557-569. https://doi.org/10.1002/aocs.12060.
Moreau, R.A., Nystrom, L., Whitaker, B.D., Moser, J.K., Baer, D.J., Gebauer, S.K., Hicks, K.B. 2018. Phystosterols and their derivatives: structural diversity, distribution, metabolism, analysis, and health promoting uses. Progress in Lipid Research. 70:35-61.
Tisserat, B., Hwang, H.-S., Vaughn, S.F., Berhow, M.A., Peterson, S.C., Joshee, N., Vaidya, B.N., Harry-O'kuru, R. 2018. Fiberboard created using the natural adhesive properties of distillers dried grains with solubles. BioResources. 13(2):2678-2701.
Kim, S., Biswas, A., Boddu, V.M., Hwang, H., Adkins, J.E. 2018. Solubilization of cashew gum from Anacardium Occidentale in aqueous medium. Carbohydrate Polymers. 199:205-209. https://doi.org/10.1016/j.carbpol.2018.07.022.
Hwang, H.-S., Fhaner, M., Winkler-Moser, J.K., Liu, S.X. 2018. Oxidation of fish oil oleogels formed by natural waxes in comparison with bulk oil. European Journal of Lipid Science and Technology. doi: 10.1002/ejlt.201700378.
Doll, K.M., Walter, E.L., Murray, R.E., Hwang, H.-S. 2018. Organogel polymers from 10-undecenoic acid and poly(vinyl acetate). Journal of Polymers and the Environment. 26:3670-3676. https://doi.org/10.1007/s10924-018-1241-4.
