Location: Functional Foods Research
2017 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 as an alternative to saturated fats or hydrogenated oils for structuring oils. For this objective, work conducted in fiscal year 2017 was aimed towards determining how the physical properties of organogels, such as crystal size, melting and crystallization temperatures, and texture, are affected by the use of different oil blends or blends of organogelators. To achieve these aims, experiments were conducted to improve the firmness of organogels by blending a fully hydrogenated oil and soybean oil and preparing organogels with the blends using sunflower wax as the organogelator. We found that the ratio of two oils significantly affected the firmness. For example, using 10% fully hydrogenated cottonseed oil increased the firmness tenfold. Increasing the level of sunflower wax from 2% to 5% did not significantly increase the firmness of the organogel. Thus, adding about 10% fully hydrogenated oil to vegetable oil is an effective method to adjust the texture of food products containing organogels while keeping the content of saturated fats relatively low. Future experiments will be conducted using fully hydrogenated soybean oil as well.
Experiments were also conducted that examined the physical properties of organogels prepared using oil and mixtures of two or more organogelators, as well as in combination with commonly used food emulsifiers. We found that the ratio and types of the ingredients used in combinations to produce organogels significantly influenced the melting and crystallization temperatures of organogels, as well as the texture. This information will enable processors to design organogels using combinations of materials to achieve desirable physical properties that can be modified depending on the needs of a particular food application.
Additional research that was conducted under this objective was aimed towards the development of an application of organogel structuring technology as a replacement for either hydrogenated oils or palm oil in an important consumer food product for the prevention of oil leakage and to improve the texture. Experiments were conducted to evaluate the impact of ingredient type and amount in preventing oil leakage both short term and over a six month period. In addition, a sensory panel has been trained to evaluate the texture and flavor of the food product, and the sensory analysis of twelve prototype products is currently underway. An invention disclosure was filed for this research.
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. Under this objective, ferulic acid: phytosterol conjugates, and ferulic acid: fatty acid conjugates were synthesized, and their thermal stability was evaluated by thermogravimetric analysis. These compounds will be used in experiments planned for the next fiscal year. The investigation of the antioxidant activity during heating and frying of twenty amino acids as well as amino acids combined with tocopherols was completed ahead of time and was published in 2017 (see the 1st publication below).
One of our hypotheses under the second objective was that wax organogels may slow the diffusion of oxygen into oils and prevent oxidation. To test this hypothesis four different natural waxes were incorporated in fish oil to form organogels, which were, in turn, subjected to oxidation at 35 and 50 °C. The effects of the cooling rate during the gelling process and the amount of wax were also investigated to find the most effective formulation and process conditions. We found that gelling fish oil with natural waxes effectively reduced the rate of oxidation, indicating that this new method can be used to prevent oxidation of omega-3 oil products and other food products containing omega-3 oils. A manuscript is in preparation.
For objective 3, blueberry pomace and spent coffee grounds were extracted with two different solvents, acetone and ethanol. In heating studies conducted at 180 °C (frying temperature), the blueberry pomace and coffee ground extracts did not demonstrate any antioxidant activity or prevent frying oil degradation. However, at a lower temperature (50 °C), they conferred excellent antioxidant protection. This indicates that valuable antioxidants can be obtained from waste products of the blueberry and coffee processing.
Accomplishments
1. Amino acids as new natural antioxidants. Frying oil degrades quickly due to the high temperatures used and rapid oxidation. Food companies would like to have natural, label-friendly antioxidants to replace synthetic antioxidants to extend oil fry-life. Certain amino acids, peptides, and protein hydrolysates are known to have antioxidant activity; however, the application of these materials as antioxidants in frying oils to replace synthetic antioxidants had never been systematically evaluated. Agricultural Research Service researchers in Peoria, Illinois, conducted studies to evaluate the antioxidant activity of 20 amino acids in soybean oil heated to frying temperature, as well as studies to evaluate the interaction between amino acids and tocopherols. The research revealed that amino acids containing a thiol, a thioether, or an extra amine group, such as arginine, cysteine, lysine, methionine, and tryptophan, had the stronger antioxidant activities than tert-butylhydroquinone (TBHQ), the synthetic antioxidant which is most commonly used in frying oils. Further studies indicated that a synergistic interaction between tocopherols, which were already present in the oil, and the added amino acids, is the most likely explanation for the strong antioxidant activity. This demonstrates that amino acids, which are inexpensive and widely available, may be used effectively as natural alternatives to synthetic antioxidants in frying oil.
2. Nuclear magnetic resonance (NMR) for rapid assessment of lipid oxidation. Lipid oxidation is a very complicated chemical process and a lack of consistency in results obtained from conventional analytical methods has been a serious problem in this research area. Hence, the development of methods that concomitantly detect different types of oxidation products is necessary for the consistent assessment of lipid oxidation. Agricultural Research Service researchers in Peoria, Illinois, developed a method for rapidly evaluating oil oxidation at frying temperatures using 1H NMR. The reliability of the new method was evaluated in several oils subjected to heating and frying. The results of the new method correlated strongly with conventional analytical methods used for the evaluation of frying oils. A slight modification was also developed to improve the reliability when oils rich in oleic acid are used. This study showed that the new NMR method can be a fast, convenient, and reliable analytical method to determine the oxidation state of frying oil which can be used by researchers or by large food companies with access to NMR for quality control.
3. An oleogel replacement for shortening in baked goods. Shortenings used in cakes are semi-solid at room temperature and contain high amounts of unhealthy saturated fats or trans unsaturated fats. Shortenings contribute significantly to the quality of aerated baked goods, they coat flour proteins and starch to provide a tender crumb, and they trap air during mixing to assist in the development and maintenance of the foam that provides the volume and aerated structure. However, advisory groups recommend that consumers lower their consumption of both saturated and trans fats, so there is a need to develop alternative technologies for replacing saturated and trans fats in shortenings, while maintaining their functional properties. Agricultural Research Service researchers in Peoria, Illinois, have developed wax-based oleogels, where liquid vegetable oils are converted to semi-solids through the addition of low levels of edible waxes, and collaborators from Sejong University, South Korea have evaluated these oleogels as replacements for shortening in cakes. Up to 25% of the shortening could be replaced with oleogel without significantly compromising the texture and cake volume, and reducing the saturated fat content of the cake by 13.3%. This research provides practical applications of oleogels as shortening replacements that can be implemented by food companies to reduce the content of unhealthy saturated fats in aerated baked goods.
Review Publications
Hwang, H.-S., Winkler-Moser, J.K. 2017. Antioxidant activity of amino acids in soybean oil at frying temperature: Structural effects and synergism with tocopherols. Food Chemistry. 221:1168-1177.
Lim, J., Hwang, H.-S., Lee, S. 2017. Oil-structuring characterization of natural waxes in canola oil oleogels: Rheological, thermal, and oxidative properties. Applied Biological Chemistry. 60:17-22.
Kim, J.Y., Lim, J., Lee, J., Hwang, H.-S., Lee, S. 2017. Utilization of oleogels as a replacement for solid fat in aerated baked goods: Physicochemical, rheological, and tomographic characterization. Journal of Food Science. 82:445-452.
Hwang, H.-S., Winkler-Moser, J.K., Liu, S.X. 2017. Reliability of ^1^H NMR analysis for assessment of lipid oxidation at frying temperatures. Journal of the American Oil Chemists' Society. 94:257-270.
Lubeckyj, R.A., Winkler-Moser, J.K., Fhaner, M.J. 2017. Application of differential pulse voltammetry to determine the efficiency of stripping tocopherols from commercial fish oil. Journal of the American Oil Chemists' Society. 94:527-536.
Bakota, E.L., Winkler-Moser, J.K. 2017. Differences in antioxidant activity between two rice protein concentrates in an oil-in-water emulsion. European Journal of Lipid Science and Technology. doi: 10.1002/ejlt.201600421.
Hwang, H.-S. 2017. Advances in NMR Spectroscopy for Lipid Oxidation Assessment. Cham, Switzerland: Springer International Publishing. 59 p.
