Location: Functional Foods Research2011 Annual Report
1a. Objectives (from AD-416)
The overall objective of the project is to improve the stability and functionality of commodity vegetable oils so they can be used as alternatives to hydrogenated oils and imported tropical fats for frying and for margarines and shortenings. To achieve this goal, we will investigate the effects of several types of phytochemicals in frying oils and will explore methods to produce healthful margarines and shortenings with low or no trans fatty acids and low saturated fats. The research will focus more specifically on the following objectives: Objective 1: Develop commercially viable methods that utilize tocopherols, phytosterols and phytosteryl ferulates to synergistically improve the oxidative stability of frying oils and fried foods; Objective 2: Develop commercially viable methods that utilize naturally-derived antioxidants and anti-polymerization compounds to improve the stability of frying oils; Objective 3: Develop commercially viable methods that utilize specialty vegetable oils to enhance the nutritional properties and oxidative stability of commodity oils; Objective 4: Develop commercially viable processing technologies to reduce or eliminate trans fatty acid content in margarines, spreads, and shortenings.
1b. Approach (from AD-416)
Food manufacturers, restaurants, and bakeries that need stable oils for frying and/or oils with the appropriate functionality for shortenings are looking for alternatives to hydrogenated oils because of trans fatty acids hydrogenated oils contain. However, commodity oils such as soybean, sunflower and corn that are processed without hydrogenation are not stable enough for frying oils nor do they have the proper functionality for margarines and shortenings. Even 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. This project proposes to improve the stability and functionality of commodity vegetable oils so they can be used as alternatives to hydrogenated oils and imported tropical fats for frying and margarines/shortenings. To help solve the problems of frying oil stability, we will: 1) Develop commercially viable methods that utilize tocopherols, phytosterols and phytosteryl ferulates to synergistically improve the oxidative stability of frying oils and fried foods; 2) Develop commercially viable methods that utilize naturally-derived antioxidants and anti-polymerization compounds to improve the stability of frying oils; and 3) Develop commercially viable methods that utilize specialty vegetable oils to enhance the nutritional properties and oxidative stability of commodity oils. To help solve functionality problems for margarines and shortenings, we will develop commercially viable processing technologies to reduce or eliminate trans fatty acid content in margarines and shortenings. Based on the results of our research, we will make recommendations to food manufacturers, oil processors and plant geneticists for developing oils with enhanced stability, functionality and healthfulness.
3. Progress Report
For Objective 1, a frying study was conducted in soybean oil and phytosterol ferulates isolated from corn and rice were added to the oil to compare their ability to protect soybean oil when frying potatoes and also to investigate the stability of the phytosterol ferulates in soybean oil. In addition, the loss of tocopherols (Vitamin E) was investigated. The results were reported in a peer-reviewed publication which was recently (June, 2011) accepted by the Journal of the American Oil Chemists Society. A heating study at frying temperature in soybean oil that was stripped of antioxidants was also conducted. Optimized ranges of tocopherols and phytosterol ferulates were added alone and in combinations, to assess the interaction between these components in preventing soybean oil polymerization as well as in assessing the interactions affecting the stability of the added phytosterol ferulates, the tocopherols, and the phytosterols. The outcomes of this research are expected to result in new functional oil products that have increased frying stability and retention of nutrients, and which may impart cholesterol-lowering phytosterols into the foods that are fried in the oil. For Objective 2, a literature review of potential antioxidants for use in frying was conducted and a list of potential natural plant components was obtained. Heating studies at frying temperature with these components added to soybean oil have been conducted. The relationship between structural features and the concentration of these natural components on two markers of oil degradation, polymerization, and loss of polyunsaturated fatty acids, have been studied. The results are currently being prepared for publication. The outcomes of this research are expected to identify natural plant antioxidants that have activity in heated oils, as well as information on how antioxidant structure impacts activity at the high temperatures used for frying. For Objective 3, we have obtained several specialty oils and have begun to analyze their composition of antioxidants as well as their stability. In addition, preliminary heating studies have been conducted by blending specialty oils with commodity vegetable oils and assessing the impact on polymerization at frying temperatures. For Objective 4, an organogel approach is being utilized to modify vegetable oils to have an increased melting point and a solid texture at room temperature. Non-triglyceride compounds, which are from natural food grade sources, were screened at different concentrations to assess their ability to increase oil melting point and to form an organogel. Melting and crystallization properties were examined using differential scanning calorimetry, microscopic analysis, viscosity, and textural properties were also studied.
1. Natural antioxidants for frying oil. During frying, oils that are high in polyunsaturated fatty acids are easily degraded by high temperatures and oxidation. These reactions cause thickening and darkening of the oil as well as destruction of essential fatty acids and vitamins. In addition, polymerized and oxidized oil will cause excessive foaming, incomplete cooking, and will impart off-flavors and poor sensory and nutritional quality to the fried food. Agricultural Research Service scientists in the Functional Foods Research Unit at the National Center for Agricultural Utilization Research in Peoria, IL, found that the addition of 0.5% phytosterol ferulates, which are natural antioxidants isolated from corn fiber, reduced the thickening of soybean oil by 70% during frying. In protecting the soybean oil, corn phytosterol ferulates also protected the tocopherols (Vitamin E) in the soybean oil by slowing down their destruction. Corn phytosterol ferulates may be added to soybean oil to increase its frying stability without the need for hydrogenation, which produces undesirable trans fatty acids. This information is useful for vegetable oil processors and food companies to develop oils and fried foods with better stability and nutritional quality.
Moser, B.R., Moser, J.K., Shah, S.N., Vaughn, S.F. 2010. Composition and physical properties of arugula, shepherd's purse, and upland cress oils. European Journal of Lipid Science and Technology. 112:734-740.