Progress 08/09/04 to 06/14/09
Outputs
Progress Report Objectives (from AD-416) To develop new knowledge about natural antioxidants that affect the quality and inherent stability of vegetable oils by investigating effects of tocopherols, tocopheron oxidation products and phytosterols and evaluating alternative technologies of oil processing. Approach (from AD-416) We will conduct frying studies to evaluate the effects of various ratios of tocopherols for enhancing both the fry life of the oil and the shelf life of fried food. The effects of various phytosterols as antipolymerization agents will be investigated. Oxidation products from tocopherols such as quinones will be investigated as potential antioxidants. In addition, new cultivars of high gamma sunflower oil will be evaluated for frying stability in comparison with traditional low gamma/high alpha sunflower oil. We will use this information to recommend optimum levels and ratios of tocopherols in edible vegetable oils for both food manufacturers and plant geneticists. We will study alternative technologies such as pressing to retain better yields of natural antioxidants and produce oils with enhanced quality and oxidative stability. We will identify those inherent phytochemicals in pressed oils that positively affect oil quality and stability. Significant Activities that Support Special Target Populations To help food manufacturers and food service operations improve the oxidative stability of frying oils and fried foods, without the need for trans fat-containing hydrogenated oils, we have developed new knowledge about the effects of natural oil constituents such as tocopherols and phytosterols as well as a new antioxidant to inhibit deterioration of frying oils and fried foods. First, we found that the best profile of tocopherols in frying oils was a combination of three tocopherols--high gamma and delta tocopherols with low alpha tocopherol to keep frying oils and fried food from deteriorating. Adding the tocopherols individually was not as effective as all three tocopherols added together, indicating a possible synergistic effect. These results are of interest to oil processors and food manufacturers in determining the appropriate antioxidant composition of oils such as soybean, sunflower, cottonseed, canola, and corn oils to maximize their quality for the 8 billion pound/year frying oil industry so they can be used without hydrogenation. Second, we found that phytochemicals extracted from distillers dried grain (DDG) oil significantly improved the oxidative stability of soybean, sunflower, and high-oleic sunflower triacylglycerols. Tocopherols, tocotrienols, and ferulate phytosterol esters in the oil all contributed to the antioxidant activity, though there may be other components in the DDG extract that also contribute to antioxidant activity. We have also isolated ferulate phytosterol esters from DDG oil that help to prevent polymerization in oils heated to frying temperatures. This is of interest to ethanol producers searching for additional markets for DDG, as well as to food processors seeking antioxidants and phytochemical compounds to enhance the nutritional properties of their food products. We are also investigating structure-function relationships of phytosterols by analyzing extracts from various plant sources such as soybean, sunflower, canola, Vernonia galamensis, and evening primrose oils which contain different profiles of some less common phytosterols. The phytosterols have been identified, and isolation is continuing. We are determining if there are differences in the antipolymerization activity of phytosterols from different plant sources and if there are any differences in activity of phytosterols with delta-5 double bonds versus delta-7 double bonds. This data will assist plant breeders in determining the best phytosterol profile to breed for better oil stability. Third, we determined that a new citric acid-based antioxidant that is heat stable to frying oil temperatures inhibits the deterioration of soy oil and food fried in it. This additive inhibited the formation of free fatty acids and total polar compounds in the frying oil and the development of off-flavor compounds in the fried food. This additive can be used as an alternative to hydrogenated oil to increase the stability of frying oil and fried food. Technology Transfer Number of Invention Disclosures submitted: 1
Impacts
(N/A)
Publications
- Warner, K.A. 2007. Increasing gamma- and delta-tocopherols in oils improves oxidative stability. Lipid Technology. 19(10):229-231.
- Winkler, J.K., Warner, K.A., Glynn, M.T. 2007. Effect of deep-fat frying on phytosterol content in oils with differing fatty acid composition. Journal of the American Oil Chemists' Society. 84:1023-1030.
- Winkler, J.K., Warner, K.A. 2008. The effect of phytosterol concentration on oxidative stability and thermal polymerization of heated oils. European Journal of Lipid Science and Technology. 110:455-464.
- Jham, G.N., Winkler, J.K., Berhow, M.A., Vaughn, S.F. 2007. Gamma- Tocopherol as a marker of Brazilian coffee (Coffea arabica L.) adulteration by corn. Journal of Agriculture and Food Chemistry. 55:5995- 5999.
- Warner, K.A., Fehr, W. 2008. Mid-Oleic/Ultra Low Linolenic Acid Soybean Oil: A Healthful New Alternative to Hydrogenated Oil for Frying. Journal of the American Oil Chemists' Society. 85:945-951.
- Warner, K.A. 2008. Food uses for soybean oil and alternatives to trans fatty acids in foods. In: Johnson, L.A., White, P.J., Galloway, R., editors. Soybeans: Chemistry, Production Processing and Utilization. Chapter 15. Urbana, IL: AOCS Press. p. 483-498.
- Warner, K.A., Miller, J.F. 2008. Oxidative Stability of Crude Mid-Oleic Sunflower Oils from Seeds with High Gamma- and Delta-Tocopherol Levels. Journal of the American Oil Chemists' Society. 85:529-533.
- Warner, K.A. 2009. High-Temperature Natural Antioxidant Improves Soy Oil for Frying. Journal of Food Science. 74(6):500-505.
- Lee, S., Inglett, G.E., Palmquist, D.E., Warner, K.A. 2008. Flavor and texture attributes of foods containing beta-glucan-rich hydrocolloids from oats. LWT - Food Science and Technology. 42(1):350-357.
- Warner, K.A. 2009. Flavor Changes During Frying. In: Sahin, S., Sumnu, S.G. , editors. Advances in Deep-Fat Frying of Foods. Boca Raton, FL: CRC Press. p. 201-213.
- Warner, K.A. 2009. Oxidative and Flavor Stability of Tortilla Chips Fried in Expeller Pressed Low Linolenic Acid Soybean Oil. Journal of Food Lipids. 16:133-147.
- Moser, J.K., Warner, K.A. 2008. Effect of Phytosterol Structure on Thermal Polymerization of Heated Soybean Oil. European Journal of Lipid Science and Technology. 110:1068-1077.
- Moser, J.K., Vaughn, S.F. 2009. Antioxidant Activity of Phytochemicals from Dried Distillers Grain Oil. Journal of the American Oil Chemists' Society. 86:1026-1035.
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Progress 10/01/06 to 09/30/07
Outputs
Progress Report Objectives (from AD-416) To develop new knowledge about natural antioxidants that affect the quality and inherent stability of vegetable oils by investigating effects of tocopherols, tocopheron oxidation products and phytosterols and evaluating alternative technologies of oil processing. Approach (from AD-416) We will conduct frying studies to evaluate the effects of various ratios of tocopherols for enhancing both the fry life of the oil and the shelf life of fried food. The effects of various phytosterols as antipolymerization agents will be investigated. Oxidation products from tocopherols such as quinones will be investigated as potential antioxidants. In addition, new cultivars of high gamma sunflower oil will be evaluated for frying stability in comparison with traditional low gamma/high alpha sunflower oil. We will use this information to recommend optimum levels and ratios of tocopherols in edible vegetable oils for both food manufacturers and plant geneticists. We will study alternative technologies such as pressing to retain better yields of natural antioxidants and produce oils with enhanced quality and oxidative stability. We will identify those inherent phytochemicals in pressed oils that positively affect oil quality and stability. Significant Activities that Support Special Target Populations We obtained new knowledge about which amounts of tocopherols inhibit oxidation and deterioration in purified frying oils using tortilla chips as a food system. We found that gamma and delta tocopherols inhibited oxidation of the aged tortilla chips fried in mid-oleic sunflower oil the best, followed by alpha tocopherol. None of the tocopherol homologues had an effect in extending the fry life of oil. We obtained new knowledge on the effects of various amounts of phytosterols in purified oils on enhancing oil stability during heating and frying. We found that the primary phytosterols existing in commodity oils such as soybean and sunflower did help to inhibit the deterioration of soybean oil heated at frying temperatures. Their addition extended the fry life of the oil. The additive combination of phytosterols to inhibit frying oil deterioration and tocopherols to inhibit oxidation in the fried food provides important information in the search for alternatives to hydrogenated oil for frying. We arranged with ARS plant geneticists in Fargo, ND, to grow out large quantities of mid-oleic with high levels of gamma and delta tocopherols as an alternative to traditional mid-oleic sunflower, which has low levels of gamma and delta tocopherols. Enough seeds were planted to yield 8 pounds of oil that is processed into refined, bleached, and deodorized oil for end-use performance testing of the oil. This has extended the research beyond just extracting the seeds to test the oxidative stability of the crude oil as we have done in the previous years. We evaluated the levels of Maillard reaction products formed in expeller pressed soybean oils and in traditional hexane extracted soybean oils and found few differences in the levels between the two types of oil processing. We evaluated the frying stability of mid-oleic/ultra low linolenic soybean oil and the retention of the tocopherols during frying. Mid-oleic/ultra low linolenic soybean oil had a fry life equal to hydrogenated soybean oil; however the mid-oleic/ultra low linolenic soybean oil retained more tocopherols than the hydrogenated soybean oil which helped to extend the shelf life of fried tortilla chips. These results are of interest to oil processors and food manufacturers in determining the appropriate antioxidant composition of oils such as soybean, sunflower, cottonseed, canola, and corn oils to maximize their quality for the 8 billion pound/year frying oil industry. Accomplishments Phytosterols may improve heat stability of oils. Vegetable oils from different sources naturally differ in content of phytosterols (for example, corn oil has twice as many phytosterols compared to soybean oil). The question investigated is whether the amount of phytosterols in a vegetable oil affects its stability to heat. We found that in soybean oil, adding phytosterols increased its heat stability, and that the higher the phytosterol content, the better the heat stability. In high- oleic sunflower oils, added phytosterols had no affect on heat stability, perhaps because the high-oleic sunflower oil is already inherently more stable. This will add to knowledge of the role of phytosterols in oil stability, and may be used by breeders for selecting plants with higher phytosterol content, or by vegetable oil processors, who may adjust their processing conditions to conserve phytosterols, or add back phytosterols lost during processing. The data was presented in May at the Annual Meeting of the American Oil Chemists' Society in Quebec City, Canada. This knowledge addresses Component I for "Quality Characterization, Preservation and Enhancement" for National Program 306 "Quality and Utilization of Agricultural Products." Mid-oleic/ultra low linolenic soybean oil is better than hydrogenated soybean oil for frying. Food manufacturers and restaurants are seeking alternatives to hydrogenated oil for frying because of problems with trans fatty acids. To determine if a new oil, mid-oleic/ultra low linolenic soybean oil has the fatty acid and tocopherol composition for enhanced frying stability, we compared the fry life and fried food stability of this oil compared to hydrogenated oil. The foods fried in mid-oleic/low linolenic soybean oil had better flavor, longer shelf life and more tocopherol retention than did the hydrogenated soybean oil. This new oil has the potential to replace hydrogenated oil for commercial frying because of enhanced stability from its fatty acid and tocopherol profiles. This new knowledge addresses Component I for "Quality Characterization, Preservation and Enhancement," for National Program 306. Investigation of phytosterol structure in relation to anti-polymerization activity in heated oils. Phytosterols are naturally occurring components in vegetable oils. There are hundreds of different phytosterols, but only five occur most commonly in vegetable oils. The question investigated is whether phytosterols with different structures, including the number and type of double bonds, affects their ability to prevent polymerization of vegetable oils heated to frying temperature. We found that phytosterols with no double bonds or with one double bond had little anti-polymerization activity. Phytosterols with two double bonds had slight anti-polymerization activity, but a phytosterol with three double bonds most significantly reduced the amount of polymers formed in heated soybean oil. This adds to the knowledge of the role of phytosterol structure on its function in heated oils. Eventually this knowledge will allow us to make recommendations to plant breeders in the selection of plants with optimum phytosterol compositions. The data was presented in May at the Annual Meeting of the American Oil Chemists� Society in Quebec City, Canada. This knowledge addresses Component I for "Quality Characterization, Preservation and Enhancement", for National Program 306. Corn dried distiller�s grain (DDG) extracts are high in phytosterols and antioxidants. Corn DDG is a by-product of the growing industry whereby ethanol is obtained from corn fermentation. It is currently sold at relatively low value as an animal feed. We found that oil extracted from DDG is high in naturally-occurring antioxidants, such as tocopherols, tocotrienols, and ferulate-phytosterol esters. It is also high in phytosterols, which are valued for their cholesterol-lowering properties. This knowledge provides a possibility for a value-added market for the DDG by-product. The valuable components could be initially extracted, leaving still a high protein and high fiber feed supplement. In addition, we are in the process of purifying some of these components to test their ability to stabilize oils during heating and frying. This knowledge addresses Component I for "Quality Characterization, Preservation and Enhancement", as well as Component II: �New Processes, New Uses, and Value-Added Foods and Biobased Products� for National Program 306. Technology Transfer Number of Non-Peer Reviewed Presentations and Proceedings: 9
Impacts
(N/A)
Publications
- Warner, K.A. 2007. Frying oil deterioration. In: Akoh, C., editor. Food Lipids: Chemistry, Nutrition and Biotechnology. Boca Raton, FL: Taylor and Francis Company. p. 71-82.
- Winkler, J.K., Rennick, K.A., Eller, F.J., Vaughn, S.F. 2007. Phytosterol and tocopherol components in extracts of corn distiller's dried grain. Journal of Agricultural and Food Chemistry. 55:6482-6486.
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Progress 10/01/05 to 09/30/06
Outputs
Progress Report 1. What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? Why does it matter? Edible vegetable oils account for 75% of the U.S. production of vegetable oils or approximately 16 billion pounds each year. Vegetable oils intended for high stability uses such as frying currently need additional processing such as hydrogenation and chemical additives to be suitable for the 8 billion pounds/per year frying oil industry. Food manufacturers are currently looking for alternatives to hydrogenated oils because of trans fatty acids; however, oils that are processed without hydrogenation are not stable enough for frying oils. Most oils with fatty acid compositions modified to increase oleic and/or to decrease linoleic or linolenic acids are still not as stable for frying as hydrogenated oils. Naturally occurring minor oil constituents such as tocopherols and phytosterols
could further enhance the stability of modified oils to have equal or better stability than hydrogenated oils. However, not enough information is available on how these phytochemicals affect product quality, stability, and end use performance. Basic research is needed to determine the relationship between product composition and desired flavor quality and stability attributes in soybean, sunflower, corn and other oils. Technologies are also needed to process oils to have better yields of naturally occurring antioxidants. If not enough appropriate edible oils for high stability applications can be produced in the U.S., food manufacturers may look to imported tropical fats such as palm or coconut as alternatives. We are developing new knowledge about naturally occurring phytochemical antioxidants in vegetable oils that affect the quality and inherent stability of edible oils. We are using various approaches to enhancing the flavor quality and oxidative stabilities of vegetable oils
such as characterizing pressed oils to understand the sources of their enhanced stability. In other efforts to improve frying oil and fried food stability, we will add natural antioxidants to oils that lack the stability needed for high stability uses such as frying. We will make recommendations to food manufacturers, oil processors and plant geneticists to develop oils with enhanced stability using phytochemicals. This project is in National Program 306 under "Quality and Utilization of Agricultural Products." This research contributes new knowledge to understand the roles of product composition for optimum end-use performance and quality of edible vegetable oils (problem area 1a on factors and processes that affect quality and problem area 1c on definition and basis of quality). This research also contributes to meeting the ARS goal for genetic improvement of oilseeds for improved attributes for good quality products in which plant breeders target particular quality attributes
in the germplasm (problem area 1d on preservation and/or enhancement of quality). 2. List by year the currently approved milestones (indicators of research progress) Year 1: Evaluate high gamma tocopherol sunflower oils; determine levels of oxidation products in frying oils; and evaluate pressed oils for frying stability. Year 2: Optimize tocopherol ratios in vegetable oils; continue studies to determine levels of oxidation products in frying oils; continue to evaluate high gamma tocopherol sunflower oils; and continue studies to evaluate pressed oils for frying stability. Year 3: Conduct studies with phytosterols; continue to optimize tocopherol ratios in vegetable oils; continue to evaluate high gamma tocopherol sunflower oils; and continue studies to evaluate pressed oils for frying stability. Year 4: Continue to optimize tocopherol ratios in vegetable oils; continue to evaluate high gamma tocopherol sunflower oils; continue studies to evaluate pressed oils for frying
stability; and continue to conduct studies with phytosterols. Year 5: Continue to optimize tocopherol ratios in vegetable oils; continue to evaluate high gamma tocopherol sunflower oils; continue studies to evaluate pressed oils for frying stability; and continue to conduct studies with phytosterols. 4a List the single most significant research accomplishment during FY 2006. Expeller pressed low linolenic acid soybean oil--a trans-free alternative to hydrogenated oils. In continuing studies on expeller pressed oils as an alternative to hydrogenated oils for frying, we found that if low linolenic acid soybean oil is expeller pressed rather than processed conventionally by hexane extraction, the stability of the oil during frying is similar to that of hydrogenated soybean oil. The combination of expeller pressing and low linolenic acid soybean oil produced a better frying oil than either expeller pressed soybean oil or low linolenic acid soybean oil individually. This project is in
National Program 306 under Component I for "Quality Characterization, Preservation and Enhancement." This research contributes new knowledge to understand the roles of product composition for optimum end-use performance and quality of edible vegetable oils (problem area 1a on factors and processes that affect quality and problem area 1c on definition and basis of quality). Currently, food manufacturers and commercial users of frying oils such as restaurants are in need of alternatives to hydrogenated oils for frying because of the trans fatty acid content imparted by hydrogenation. In pilot plant frying studies conducted by the ARS Potato Research Worksite in East Grand Forks, MN and in batch frying tests conducted at our research center, we found that low linolenic acid soybean oil that had been expeller pressed was superior to regular soybean oil that had been expeller pressed. Oil processors and food manufacturers now have new oil- -expeller pressed low linolenic acid soybean
oil--as a trans-free alternative to hydrogenation or added antioxidants in edible oils. 4d Progress report. In studies on the effects of expeller pressing of oils to enhance frying stability, we conducted pilot-plant continuous frying trials of potato chips and non-continuous batch frying trials of tortilla chips using oils including expeller pressed soybean oil, expeller pressed low linolenic soybean oil, partially hydrogenated soybean oil, high oleic sunflower oil, and corn oil. We found that the expeller pressed low linolenic acid soybean oil had better stability than the expeller pressed soybean oil. In most tests, the expeller pressed low linolenic acid soybean oil was as stable as hydrogenated soybean oil or high oleic sunflower oil. In studies to measure the phytosterols content of the frying oils, we found that corn oil had 2-3 times higher content than the other oils. Phytosterol content of the expeller pressed soybean oil was not higher than that of regular soybean oil.
However, the phytosterol content of expeller pressed low linolenic soybean oil was higher than both expeller pressed regular, and hydrogenated soybean oil, indicating that there may be environmental or varietal influences on phytosterol content. Phytosterols were not susceptible to much loss in any of the oils during the continuous frying process. Corn oil had the highest loss at 5%. More phytosterols were lost during the batch frying process, most likely because the oil was used for a longer period of time. The formation of degradation products called polymers was lower during continuous frying than batch frying. During batch frying, the formation of polymers was highest in the regular soybean oil and expeller pressed soybean oil, probably because of their higher content of polyunsaturated fatty acids. The expeller pressed low linolenic soybean oil and the high oleic sunflower oil both had slightly less polymer formation than corn oil, while the hydrogenated soybean oil still had
the lowest formation. We conducted studies to determine the fate of tocopherol oxidation products in oil heated to frying temperatures. Some of our previous results have shown that tocopherols volatilize or disappear rapidly during frying. As tocopherols decompose during this process, they form breakdown products such as quinones also can have antioxidant properties. Since some quinones can act as antioxidants even after the tocopherols have decomposed, we conducted studies on oils heated to frying temperature and found that alpha tocopherol quinones levels increased as alpha tocopherol levels decreased in soybean and sunflower oils. The quinones themselves then decrease over time. This study showed that alpha tocopherol quinones are present in frying oils and may help to inhibit oxidation in frying oils and fried foods. These results could also help explain why oils that lose all of their tocopherol content still have some inhibition to oxidation. We recommended that ARS plant
geneticists develop sunflowers with high levels of gamma and delta tocopherols as an alternative to traditional sunflower, which has low levels of gamma and delta tocopherols. We evaluated oil extracted from sunflower seeds bred to have high levels of gamma and delta tocopherols and found that the oil was significantly more oxidatively stable than sunflower oil with the regular low gamma tocopherol content. These results are of interest to oil processors and food manufacturers in determining the appropriate antioxidant composition of oils such as soybean, sunflower, cottonseed, canola, and corn oils to maximize their quality for the 8 billion pound/year frying oil industry. 5. Describe the major accomplishments to date and their predicted or actual impact. Two major accomplishments have been made during this project. First, we recommended that ARS plant geneticists breed sunflowers with increased levels of gamma and delta tocopherols. In the resulting cultivars, we found that
crude sunflower oils extracted from the seeds were significantly improved in quality and stability if the tocopherol content was modified from its regular high alpha tocopherol content to high gamma and delta tocopherol content. More research is needed to grow out seeds that have the most effect on oil quality and to process the oil into deodorized oil to conduct full-scale frying studies. This information will be used by plant breeders in the future when issues such as yield and cost are resolved. This project is in National Program 306 under Component I for "Quality Characterization, Preservation and Enhancement." This research contributes to meeting the ARS goal for genetic improvement of oilseeds for improved attributes for good quality products in which plant breeders target particular quality attributes in the germplasm (problem area 1d on preservation and/or enhancement of quality). Second, in continuing studies on expeller pressed oils as an alternative to hydrogenated oils
for frying, we found that if low linolenic acid soybean oil is expeller pressed rather than processed conventionally by hexane extraction, the stability of the oil during frying is similar to that of hydrogenated soybean oil. The combination of expeller pressing and low linolenic acid soybean oil produced a better frying oil than either expeller pressed soybean oil or low linolenic acid soybean oil individually. This project is in National Program 306 under Component I for "Quality Characterization, Preservation and Enhancement." This research contributes new knowledge to understand the roles of product composition for optimum end-use performance and quality of edible vegetable oils (problem area 1a on factors and processes that affect quality and problem area 1c on definition and basis of quality). Currently, food manufacturers and commercial users of frying oils such as restaurants are in need of alternatives to hydrogenated oils for frying because of the trans fatty acid content
imparted by hydrogenation. In pilot plant frying studies conducted by the ARS Potato Research Worksite in East Grand Forks, MN, and in batch frying tests conducted at our research center, we found that low linolenic acid soybean oil that had been expeller pressed was superior to regular soybean oil that had been expeller pressed. Oil processors and food manufacturers now have new oil- -expeller pressed low linolenic acid soybean oil--as a trans-free alternative to hydrogenation or added antioxidants in edible oils. 6. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end- user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? Based on studies of sunflower oils from seeds bred to have high levels of gamma and delta tocopherols, we recommended that ARS plant geneticists develop sunflower seeds with specific
amounts of alpha, gamma and delta tocopherols. During the 2006 growing season, the seeds from these cultivars will be harvested and sent to our research center for analysis. These sunflower seeds have the potential to be a value-added product within the next several years. The initial higher cost of seeds with modified tocopherol content will probably affect the use of this oil. In addition, new knowledge about the trans-free alternatives to hydrogenated frying oil such as expeller pressed oil has been developed and transferred to oil processors and food manufacturers through presentations, publications, workshops, short courses and visits with company representatives. They can use this information to develop new oils that will provide healthful, better tasting foods. In addition, plant breeders can use this information to develop new cultivars of oilseeds with enhanced profiles of tocopherols. 7. List your most important publications in the popular press and presentations to
organizations and articles written about your work. (NOTE: List your peer reviewed publications below). Warner, K. 2005. Loss of tocopherols in frying oils, fried foods and salad oils, 26th World Congress and Exhibition of the ISF, Prague, Czech Republic. Warner, K., Glynn, M. 2006. Effects on quality and oxidative stability of snack foods fried in expeller pressed oils. Institute of Food Technologists Annual Meeting, Orlando, FL. Warner, K., Miller, J.F., Demurin, Y. 2006. Oxidative stability of crude mid-oleic sunflower oils from seeds with high gamma and delta tocopherol levels. Annual Meeting and Expo of the American Oil Chemists Society. Warner, K. 2006. Flavor development in high stability oils during frying. Annual Meeting and Expo of the American Oil Chemists Society. Warner, K. 2006. Trans-free frying oils--Alternatives to hydrogenated fats. Trans-free Workshop, Oklahoma State University, Stillwater, OK. Warner, K. 2006. Characteristics of frying oils and fried foods. Short
Course on Frying Oils, Institute of Food Technologists, Chicago, IL. Winkler, J.K., Warner, K., Glynn, M.T. 2006. Effect of deep-fat frying on phytosterol and polymerized triacylglycerol content in oils with differing fatty acid composition. Annual Meeting and Expo of the American Oil Chemists Society.
Impacts
(N/A)
Publications
- Warner, K.A., Dunlap, C.A. 2006. Effects of expeller pressed/physically refined soybean oil on frying oil stability and flavor of french-fried potatoes. Journal of the American Oil Chemists' Society. 83(5):435-441.
- Warner, K.A. 2005. Effects on the flavor and oxidative stability of stripped soybean and sunflower oils with added pure tocopherols. Journal of Agricultural and Food Chemistry. 53(26):9906-9910.
- Warner, K.A. 2006. Flavor development in high stability oils during frying [abstract]. 97th Annual Meeting and Expo of the American Oil Chemists' Society. p. 44.
- Winkler, J.K., Warner, K.A., Glynn, M.T. 2006. Effect of deep-fat frying on phytosterol and polymerized triacylglycerol content in oils with differing fatty acid composition [abstract]. 97th Annual Meeting and Expo of the American Oil Chemists' Society. p. 89.
- Lee, S., Warner, K.A., Inglett, G.E. 2005. Rheological properties and baking performance of new oat beta-glucan-rich hydrocolloids. Journal of Agricultural and Food Chemistry. 53(25):9805-9809.
- Rennick, K.A., Warner, K.A. 2006. Effect of elevated temperatures on development of tocopherolquinones in oils. Journal of Agricultural and Food Chemistry. 54:2188-2192.
- Warner, K.A. 2006. Methods of analysis to determine the quality of oils. In: Gunstone, F., editor. Modifying Lipids for Use in Foods. Cambridge, UK: Woodhead Publishing Ltd. p. 15-30.
- Warner, K.A., Glynn, M.T. 2006. Effects on quality and oxidative stability of snack foods fried in expeller pressed oils [abstract]. 2006 Institute of Food Technologists Annual Meeting and Food Expo. p. 23.
- Warner, K.A., Miller, J.F., Demurin, Y. 2006. Oxidative stability of crude mid-oleic sunflower oils from seeds with high gamma and delta tocopherol levels [abstract]. 97th Annual Meeting and Expo of the American Oil Chemists' Society. p. 19.
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Progress 10/01/04 to 09/30/05
Outputs
1. What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? What does it matter? Edible vegetable oils account for 75% of the U.S. production of vegetable oils or approximately 16 billion pounds each year. Vegetable oils intended for high stability uses such as frying currently need additional processing such as hydrogenation and chemical additives to be suitable for the 8 billion pounds/per year frying oil industry. Food manufacturers are currently looking for alternatives to hydrogenated oils because of trans fatty acids; however, oils that are processed without hydrogenation are not stable enough for frying oils. Most oils with fatty acid compositions modified to increase oleic and/or to decrease linoleic or linolenic acids are still not as stable for frying as hydrogenated oils. Naturally occurring minor oil constituents such as tocopherols and phytosterols could further
enhance the stability of modified oils to have equal or better stability than hydrogenated oils. However, not enough information is available on how these phytochemicals affect product quality, stability, and end use performance. Basic research is needed to determine the relationship between product composition and desired flavor quality and stability attributes in soybean, sunflower, corn and other oils. Technologies are also needed to process oils to have better yields of naturally occurring antioxidants. If not enough appropriate edible oils for high stability applications can be produced in the U.S., food manufacturers may look to imported tropical fats such as palm or coconut as alternatives. We are developing new knowledge about naturally occurring phytochemical antioxidants in vegetable oils that affect the quality and inherent stability of edible oils. We are using various approaches to enhancing the flavor quality and oxidative stabilities of vegetable oils such as
characterizing pressed oils to understand the sources of their enhanced stability. In other efforts to improve frying oil and fried food stability, we will add natural antioxidants to oils that lack the stability needed for high stability uses such as frying. We will make recommendations to food manufacturers, oil processors and plant geneticists to develop oils with enhanced stability using phytochemicals. This project contributes to National Program 306 under Component I for "Quality Characterization, Preservation and Enhancement." This research contributes new knowledge to understand the roles of product composition for optimum end-use performance and quality of edible vegetable oils (problem area 1a on factors and processes that affect quality and problem area 1c on definition and basis of quality). This research also contributes to meeting the ARS goal for genetic improvement of oilseeds for improved attributes for good quality products in which plant breeders target
particular quality attributes in the germplasm (problem area 1d on preservation and/or enhancement of quality). 2. List the milestones (indicators of progress) from your Project Plan. Year 1: Evaluate high gamma tocopherol sunflower oils; determine levels of oxidation products in frying oils; and evaluate pressed oils for frying stability. Year 2: Optimize tocopherol ratios in vegetable oils; continue studies to determine levels of oxidation products in frying oils; continue to evaluate high gamma tocopherol sunflower oils; and continue studies to evaluate pressed oils for frying stability. Year 3: Conduct studies with phytosterols; continue to optimize tocopherol ratios in vegetable oils; continue to evaluate high gamma tocopherol sunflower oils; and continue studies to evaluate pressed oils for frying stability. Year 4: Continue to optimize tocopherol ratios in vegetable oils; continue to evaluate high gamma tocopherol sunflower oils; continue studies to evaluate pressed oils
for frying stability; and continue to conduct studies with phytosterols. Year 5: Continue to optimize tocopherol ratios in vegetable oils; continue to evaluate high gamma tocopherol sunflower oils; continue studies to evaluate pressed oils for frying stability; and continue to conduct studies with phytosterols. 3a List the milestones that were scheduled to be addressed in FY 2005. For each milestone, indicate the status: fully met, substantially met, or not met. If not met, why. 1. Evaluate high gamma tocopherol sunflower oils; determine levels of oxidation products in frying oils; and evaluate pressed oils for frying stability. Milestone Fully Met 3b List the milestones that you expect to address over the next 3 years (FY 2006, 2007, and 2008). What do you expect to accomplish, year by year, over the next 3 years under each milestone? The milestones for the future project plan are as follows: to optimize tocopherol ratios in vegetable oils; to evaluate high gamma tocopherol
sunflower oils; to evaluate pressed oils for frying stability; and to conduct studies with phytosterols. In FY 2006, 2007, and 2008, we will determine the effects of antioxidants and antipolymerization compounds in frying oils and fried food. This will affect the types and amounts of degradation compounds measured in the in frying oils and fried foods. We expect that these compounds will improve frying oil stability and extend fry life of fried food. Specifically, we will add tocopherols in various ratios and amounts to oils such as soybean and sunflower that have had all minor constituents removed. The frying oil stability and fried food quality of the oils will be evaluated by chemical, instrumental and sensory methods. We will also continue to work with ARS plant geneticists to optimize the levels of gamma and alpha tocopherols in sunflower seeds in order to enhance the oxidative stability of traditional sunflower oil. Each year we will evaluate the stability of oil from
various cultivars and get greater grow-outs of the seeds for larger-scale processing. A pilot- plant frying study of expeller oil will be conducted to produce potato chips that will be compared for quality and stability in comparison with traditionally processed oils. We will conduct systematic studies of the effect of phytosterols on oil degradation and polymerization during heating and frying. At first, pilot studies will be conducted to screen phytosterols and determine which have promise as protective agents. For larger scale studies, phytosterols may need to be isolated and purified in larger quantities. Oils from various plant origins, and which have been stripped of their endogenous antioxidants will be used as a medium for heating and frying studies. Phytosterols will be added individually at varying levels, and the rate of deterioration and polymerization of the oils during heating and frying will be determined. For those phytosterols that are protective against oil
degradation during heating and frying, combinatorial studies will be conducted to determine whether they protect synergistically. We anticipate that these studies will provide information on the protective role that phytosterols components have in oils. This information will be passed on to plant breeders, especially if individual phytosterols are found to confer a higher level of protection than others. In addition, the oil processing industry will benefit from this information so that processing conditions can be optimized to retain as many beneficial components as possible. Finally, the food industry may benefit from knowledge of phytosterol components that could potentially be used as oil stabilizers. 4a What was the single most significant accomplishment this past year? Based on our initial studies of the antioxidant effects of gamma tocopherol in oils, we recommended to sunflower plant geneticists that they breed sunflowers with high levels of gamma tocopherol as an
alternative to the current sunflower seed with low gamma tocopherol with the intent of producing more oxidatively stable sunflower oil. Jerry Miller, an ARS plant geneticist, developed several cultivars of sunflower seeds with high levels of gamma tocopherol and grew these sunflowers for us. We extracted the oil from the seeds and conducted oxidative stability tests on the oils. Results indicated that the sunflower seed oils with high amounts of gamma tocopherol were more oxidatively stable than traditional sunflower oil with low levels of gamma tocopherol. In addition, frying studies with soybean oils that had been commercially processed using expelling and physical refining were conducted to determine existence of any differences between soybean oils processed using traditional solvent extraction and chemical refining. The frying stability of expeller pressed soybean oil was significantly better than soybean oil with no additives, but similar to the stability of soybean oil with
Tertiary Butyl Hydroquinone (TBHQ) or hydrogenated soybean oil. We found that the Maillard reaction products from expeller pressing were a possible source of the enhanced oil stability. Food manufacturers may want to consider using expeller pressed oil as an alternative to hydrogenation or added antioxidants in edible oils. 4d Progress report. We evaluated oil extracted from the high gamma sunflower seeds and found that the oil was significantly more oxidatively stable than sunflower oil with the typical low gamma tocopherol content. We also determined that quinones were formed from the breakdown of tocopherols during frying. Because quinones are known to have antioxidant activity, this helps explain at least in part why oils that lose all of their tocopherol content still have some inhibition to oxidation. We found that pressed soybean oil had enhanced frying stability compared to traditional solvent extracted soybean oil. Compositional analyses of the oils indicated few
differences to explain the enhanced stability. However, additional tests showed that the pressed oils contained Maillard reaction products that are known to act as antioxidants. The conditions that are used to process pressed soybean oil produce these Maillard reaction products. 5. Describe the major accomplishments over the life of the project, including their predicted or actual impact. We determined the effects of gamma tocopherol, ferulic acid and oryzanol in frying oils and found that they each inhibited deterioration of both the frying oil and the fried food during storage. Even when the gamma tocopherol was at very low levels or not detectable, we still saw a positive effect of the addition of gamma tocopherol, presumably because of the tocopherol oxidation products such as tocopherol quinones that have antioxidant activity. Based on this knowledge, we asked plant geneticists to develop sunflowers with high levels of gamma tocopherol as an alternative to traditional
sunflower, which has low levels of gamma tocopherol. Analyses of the resulting oil showed that sunflower oil bred to have high levels of gamma tocopherol were more oxidatively stable than regular sunflower oil with low amounts of gamma tocopherol. These results are of interest to oil processors and food manufacturers in determining the appropriate antioxidant composition of oils such as soybean, sunflower, cottonseed, canola, and corn oils to maximize their quality for the 8 billion pound/year frying oil industry. 6. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end- user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? We recommended that ARS plant geneticists develop sunflower seeds with high levels of gamma tocopherol. Our results of the high gamma sunflower oil showed significant improvement of the
oxidative stability of the oil. The high-gamma cultivars will be grown in large amounts in 2005. These sunflower seeds have the potential to be a value-added product within the next several years. In addition, new knowledge about the role of antioxidants during frying and during storage has been developed and transferred to oil processors and food manufacturers through presentations, publications and visits with company representatives. They can use this information to develop new oils that will provide healthful, better tasting foods. In addition, plant breeders can use this information to develop new cultivars of oilseeds with enhanced profiles of tocopherols. 7. List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below). Warner, K. 2005. Assessing the effects of antioxidants in frying oils and fried foods. American Chemical Society, Second International
Congress on Antioxidants, Orlando, FL. Warner, K. 2005. Quality of fried food. 5th International Symposium on Deep-Fat Frying. Euro-Fed Lipid, San Francisco, CA. Warner, K. 2005. Frying oils and fried foods. Lipid Oxidation Short Course, American Oil Chemists' Society meeting, Salt Lake City, UT.
Impacts
(N/A)
Publications
- Rennick, K.A., Abidi, S., Warner, K.A. 2005. Effect of elevated temperatures on development of tocopherolquinones in oils. Annual Meeting and Expo of the American Oil Chemists' Society. p. 46.
- Decker, E.A., Warner, K.A., Richards, M. 2005. Measuring antioxidant effectiveness in foods. Journal of Agricultural and Food Chemistry. 53:4303-4310.
- Warner, K.A., Laszlo, J.A. 2005. Addition of ferulic acid, ethyl ferulate, and feruloylated monoacyl- and diacylglycerols to salad oils and frying oils. Journal of the American Oil Chemists' Society. 82(9):647-652.
- Warner, K.A., Gupta, M. 2005. Potato chip quality and frying oil stability of high oleic acid soybean oil. Journal of Food Science. 70(6):395-400.
- Pintauro, P.N., Gil, M., Warner, K.A., List, G.R., Neff, W. 2005. Electrochemical hydrogenation of soybean oil with hydrogen gas. Industrial and Engineering Chemistry Research. 44:6284-6292.
- Warner, K.A. 2004. Effects of tocopherol ratios on oxidative stability of soybean oil triacylglycerols. American Chemical Society Abstracts. p. 251.
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