Location: Functional Foods Research
2024 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 oil and fried foods. The overall goal is to develop synergistic antioxidant combinations that can be used to improve frying oil life and the shelf-life of fried foods. In support of Sub-objective 1.A, ARS researchers in Peoria, Illinois, conducted frying studies of sweet potatoes in canola oil with a variety of added antioxidants either alone or in combinations. Then they studied the effect of the antioxidants and combinations on the shelf-life of the sweet potato chips under accelerated storage conditions at a temperature of 55°C, analyzing headspace volatiles, tocopherol and beta- carotene loss from chips, and oxidative stability index (OSI). The secondary goal of their studies was to determine if oxidative stability index (OSI) and tocopherol analysis could be used as faster indicators or predictors for shelf-life. Using canola oil as the negative control, and tert-butylhydroquinone (TBHQ) as the positive control, ARS researchers in Peoria, Illinois, were able to demonstrate increased shelf-life with combinations of antioxidants including ascorbyl palmitate (an oil soluble vitamin C), methionine, and phytosteryl ferulates.
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 milestone for the project was to complete shelf-life testing of margarines or other foods developed with oleogels under Objective 2, and so the progress under Sub-objective 1.B and Sub-objective 2.A are interrelated. In their previous studies, ARS researchers in Peoria, Illinois, found that the mixture of beeswax (BW) and candelilla wax (CDW) provided oleogels with higher gel strength and lower melting point than those with either wax alone. In addition, the improvement by mixing two waxes was also observed with margarine formulations. For the practical application of oleogels with this binary wax system, it was important to examine the physical stability of these margarine systems. Margarines were prepared using a typical formulation containing skim milk, salt, emulsifiers, and other ingredients where conventional fats were replaced with a 5% mixture of BW and CDW (1:1). Margarine samples were evaluated for their firmness, cohesiveness, and adhesiveness during storage at room temperature (21-22°C) after 15, 30, and 60 days. While physical properties of the margarine did not significantly change up to 15 days, firmness and cohesiveness decreased to 89% and 87% from the initial margarine, respectively, after 60 days. In contrast, adhesiveness of the margarine increased by 15% after 60 days. A similar trend was observed with oleogels alone during storage indicating that the decrease in the firmness of margarine may be attributed to the decrease in oleogel firmness. Further studies will be conducted to confirm the current conclusions in this study. In addition, oxidative stability studies with and without added antioxidants will commence, based on the results from Sub-objective 2.
Sub-objective 2.A is to investigate and optimize the physical and sensory properties as well as the oxidative stability of edible oleogels. As progress towards this sub-objective, oleogels with a 1:1 mixture of BW and CDW were prepared since ARS researchers in Peoria, Illinois, found these to be one of the most promising wax combinations for use as fat substitutes due to their high gel strength and relatively low melting temperature. They were prepared with three different vegetable oils, olive, soybean, and flaxseed oils that are rich in oleic, linoleic, and linolenic acids, respectively. Two wax concentrations, 3 and 7% and two storage temperatures, 4 and 25°C, were used.
Oxidation of oleogels was determined by peroxide value (PV) and conjugated diene value (CDV). PV and CDV of oleogels increased slower than the corresponding bulk oils at 4°C, but they increased faster than those of bulk oils at 25°C indicating that oleogelation decreased oil oxidation during storage at refrigeration temperature but not a room temperature. Most oleogels showed slightly faster oxidation than the fat from a commercial margarine indicating that additional protection is needed for practical product development with these oleogels. Olive oil contained 69.4% oleic acid while soybean oil contained 57.2% linoleic acid as their major fatty acid. Since oleic acid is much more stable than linoleic acid to oxidation, higher oxidative stability was expected with olive oil oleogels. However, olive oil oleogels oxidized faster than soybean oil oleogels indicating that inherent antioxidants in soybean oil effectively prevented oil oxidation. Soybean oil contained higher phenolics (38.5 mg gallic acid equivalent (GAE)/100 g vs. 17.5 mg GAE/100g) as well as higher total tocopherols (1643.7 µg/g vs. 316.0 µg/g) than olive oil.
Sub-objective 2.B is to evaluate interesterified natural waxes, waxes with vegetable oils, fatty alcohols, or fatty acids, as potential new oleogelators. In progress towards this sub-objective, ARS researchers in Peoria, Illinois, evaluated sophorolipid based hydroxy fatty acids as well as hydrogenated Lesquerella oil as potential oleogelators. ARS researchers in Peoria, Illinois, collaborated with ARS researchers at Wyndmoor, Pennsylvania, who provided some of the hydroxy fatty acids from fermentation of special yeast cultures. ARS researchers also collaborated with ARS researchers in the BioOils Research Unit, Peoria, Illinois, that provided fully hydrogenated Lesquerella oil, which has 62% hydroxy fatty acids. Using these unique and renewable sources of hydroxy fatty acids, the ARS researchers in Peoria, Illinois, determined the minimum concentration of these substances needed to form an oleogel with soybean oil, and also evaluated the physical and rheological properties of the resulting oleogels in comparison to the industry standard, 12-hydroxy stearic acid, which is extracted from the toxic source, castor seed oil.
Objective 3 is to improve commercial value and sustainable food production through recovery of healthful bioactive ingredients from food processing by-products or waste. As progress towards this objective, ARS researchers in Peoria, Illinois, collaborated with ARS scientists in Fort Pierce, Florida, to analyze tocopherols, peroxide value, p-anisidine value, and phytosterols in oil extracted from sour orange oil seeds.
Under Objective 3, ARS researchers in Peoria, Illinois, also evaluated silflower seed oil composition, as a potential new drought-resistant perennial oilseed, and potential source of squalene. The effect of bleaching clays on chlorophyll content and oxidative stability of the silflower seed oil was also evaluated.
In an agreement with a small business, ARS researchers in Peoria, Illinois, also completed evaluations of the frying stability of a new long-chain monounsaturated frying oil that may soon be commercialized.
ARS researchers in Peoria, Illinois, also evaluated major antioxidant components in different coffee retentate extracts and their antioxidant activity revealed that caffeic acid, 3,4-dihydroxybenzoic acid, gallic acid, and chlorogenic acid had strong correlations with the antioxidant activity. For further understanding on their antioxidant activity, each component at the concentration of 0.01% (w/w) in stripped soybean oil, where all the polar compounds were removed, was examined during storage at 35°C for 20 days. It was found that gallic acid was the strongest antioxidant, with activity similar to mixed tocopherols. Caffeic acid also showed strong antioxidant activity after gallic acid. The same study was conducted with stripped flaxseed oil, and caffeic acid and gallic acid were found to be the strongest antioxidants while their activity was not as strong as mixed tocopherols in this oil. Based on these results, ARS researchers in Peoria, Illinois, have decided to change the process to increase the contents of gallic acid and caffeic acid. The first step is to conduct hydrolysis of the coffee retentate under several conditions using different bases, different concentrations of bases, and different temperatures. The hydrolyzed coffee retentate will be extracted with acetone and other solvents, and the concentrations of gallic acid and caffeic acid will be analyzed.
Accomplishments
1. Improving fat substitute properties to reduce saturated fats and prevent heart disease. Current dietary recommendations to help prevent heart disease are to reduce saturated fats in the diet and replace them with vegetable oils that are higher in healthy monounsaturated and polyunsaturated fatty acids. However, replacing fats with oil is difficult to achieve in some food products because oil is not solid at room or refrigerated temperatures. ARS researchers in Peoria, Illinois, were able to demonstrate important interactions between sunflower wax and different types of oil compositions so that achieving fat replacements with specified texture and melting points will be easier to achieve. The information obtained from this study is valuable to fats and oil companies, not only for fundamental understanding on the factors affecting the properties of oleogel-based fat substitutes, but also for the development of healthy food products from these oleogels.
2. Silflower: A potential new perennial oilseed and squalene source for protection of sharks. Silflower is a drought-tolerant perennial plant in the sunflower family native to the central United States. Replacing annual food crops with perennial food crops can protect soil from erosion, reduce pesticide and herbicide use, and increase nutrient and water retention and carbon sequestration. However, to compete economically with annual oilseeds, silflower agronomic trait improvements are needed such as seed size, oil yield, and oil stability. ARS researchers in Peoria, Illinois, analyzed the yield, composition, and oxidative stability of silflower oil. In doing so, they discovered that silflower oil contained unusually high (up to 4.8%) concentrations of squalene, which is in demand in nutraceutical, cosmetic, and pharmaceutical industries. Currently squalene is obtained from shark liver oil, which is controversial due to international concerns with shark overfishing. Silflower oil has similar fatty acid and tocopherol composition to confectionary sunflower oil, the type that is consumed as a snack. In addition, silflower oil stability was compromised by high chlorophyll content, which could be counteracted by refining or by breeding efforts to reduce chlorophyll upon harvest. This information provided breeding strategies to improve the oxidative stability and optimize squalene in silflower oil, so that it can successfully progress from a perennial flower to a perennial climate resilient oilseed crop and renewable squalene source.
3. Industrially important fatty acids from renewable sources and demonstration of their oil-gelling properties. Hydroxy fatty acids have many important uses in industrial chemistry. Unfortunately, castor seed oil, which produces the toxin, ricin, is the only major commercial source of hydroxy fatty acids, so there is great interest in new and renewable sources for hydroxy fatty acids. Sophorolipids from yeast are one potential new source of hydroxy fatty acids. ARS researchers in Peoria, Illinois, and in Wyndmoor, Pennsylvania, evaluated the oleogel properties of sophorolipid derived hydroxy fatty acids and hydroxy fatty acid methyl esters. Oleogels are semi-solid fat-like materials that can be used as fat replacements in foods or as creams for drugs or cosmetics. Materials such as fatty acids, waxes, or monoglycerides, are melted in oils and when they cool, they form a network of fibers or crystals that bind the liquid oil and form a semi-solid similar to a natural fat, and hydroxy fatty acids were one of the first materials that were used to form oleogels. Sophorolipid-derived hydroxy fatty acids were able to form oleogels at 5% -10% in soybean oil, thus may serve as a renewable and non-toxic source of biobased hydroxy fatty acids that could be useful for replacing saturated fats in food and may also be useful in cosmetics and pharmaceuticals.
Review Publications
Winfield, D.D., Dunn, R.O., Moser, J.K., Cermak, S.C., Marks, M.D. 2024. Characterization, physical properties, and potential industrial applications of high oleic pennycress oil. Industrial Crops and Products. https://doi.org/10.1016/j.indcrop.2024.118095.
Moser, J.K., Ashby, R.D., Yosief, H.O., Msanne, J.N., Peterson, S.C., Bantchev, G.B., Cermak, S.C., Felker, F.C. 2024. Properties of soybean oil oleogels produced from sophorolipid-derived hydroxy fatty acids, methyl esters and hydrogenated Lesquerella seed oil. Journal of the American Oil Chemists' Society. https://doi.org/10.1002/aocs.12843.
Hwang, H., Liu, S.X., Moser, J.K., Singh, M., Van Tassel, D.L. 2024. Composition and oxidative stability of silflower (Silphium integrifolium) seed oil and its potential as a new source of squalene. Journal of the American Oil Chemists' Society. https://doi.org/10.1002/aocs.12814.
Hwang, H., Kim, S., Moser, J.K. 2024. Unsaturation and polar compounds of vegetable oils affect the properties of sunflower wax oleogels. European Journal of Lipid Science and Technology. https://doi.org/10.1002/ejlt.202300205.
Hwang, H., Moser, J.K. 2024. Wax-based oleogels. In: Palla, C., Valoppi, F., editors. Advances in Oleogel Development, Characterization, and Nutritional Aspects. Switzerland: Springer Nature. p. 133-155. https://doi.org/10.1007/978-3-031-46831-5.
Hwang, H.-S., Winkler-Moser, J.K. 2024. Physical and oxidative stability of oleogels during storage. In: Palla, C., Valoppi, F., editors. Advances in Oleogel Development, Characterization, and Nutritional Aspects. Switzerland: Springer Nature. p. 365-395.